Urine dipsticks

Community paediatrics / Emergency / General paediatrics / Neonatology / Renal / Urology
Cite this article as:
Laura Riddick. Urine dipsticks, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.32596

This post will cover what’s what on a urine dipstick and clarify what it means when “it lights up like a Christmas tree“

It’s 3 am and the 4-year-old with fever has finally produced a urine sample. You dip it and it lights up “positive for everything”. You’re sure it’s positive for infection, but what if the pH is 5.5? What does it mean that there is blood and protein in it?

Leukocytes

Surely white blood cells must mean an infection is present? If you have read the NICE UTI guidelines, so you know that is not necessarily the case.

The dipstick tests for leukocyte esterase. This is an enzyme produced by neutrophils and can be a sign of a urinary tract infection (white cells in urine = pyuria). These neutrophils, however, and the enzyme they produce can also be a sign of infection outside of the body such as vulvovaginitis. They may also be found in the presence of haematuria.

The overall sensitivity for leukocyte esterase is 49 – 79% with a specificity of 79 – 87%. As a result, it can be considered to be suggestive of “possible UTI”, and “probable UTI” if found with a positive nitrite sample (specificity increased to 99%).

What does this mean/bottom line: If positive and history suggestive (i.e. dysuria or fever) consider UTI and send for culture. If negative, then it is quite unlikely that there is an infection.

Nitrites

Nitrites are the breakdown product by gram-negative organisms such as E.coli. They are a more specific test (93-98%) than leukocytes but their sensitivity is lower (47-49%). The sensitivity is particularly poor as the urine needs to sit in the bladder for a while (at least 4 hours) for it to be positive.

What does this mean/bottom line: If it is positive, it is highly suggestive of infection. If it is negative, then does not necessarily rule out infection and needs correlation with leukocytes and presentation

Blood

Blood (haematuria) can be present for many reasons, so it is important to determine if there is microscopic (dipstick only) or macroscopic (visibly bloody). If blood is seen seen with leukocytes and/or nitrites then you should consider the child to have a UTI. If blood is seen with protein, then glomerulonephritis needs to be considered as a cause.

Causes of haematuria

  • Infection
  • Fever
  • Kidney stones
  • Glomerulonephritis
  • Renal tumour
  • Exercise
  • Trauma
  • Menstruation (doesn’t cause haematuria but will show up on dipstick so don’t forget to ask)

Isolated microscopic haematuria is common and only needs investigation if persistent, but make sure a blood pressure is checked as this is an often missed test. If haematuria is persistent it may need further investigation.

Reasons for further investigation

  • Macroscopic haematuria
  • Proteinuria
  • High blood pressure
  • Clinical oedema or features of fluid overload
  • Persisting microscopic haematuria (>2 occasions over 2-4 weeks apart)

Bottom line: If just microscopic haematuria on dipstick without explanation, then request a repeat sample with GP in 2-4 weeks. Don’t forget to check a blood pressure!

Protein

The body excretes a small amount which is usually not enough to pick up on dipstick.

If the body is “stressed” in illness or infection, it can cause proteinuria, however it is also a sign of inflammation or damage within the kidney and so further history and examination is required.

When there is proteinuria of 2+ or more occurs during illness or a UTI, it can be repeated in a couple of weeks to ensure that it does not persist when the patient is well.

If there is no illness or infection, you would need to consider other causes such as glomerulonephritis and nephrotic syndrome, examine for oedema, and send off a protein:creatinine ratio sample.

Bottom line: small amounts can be seen in illness, but large amounts needs review depending on how the patient is.

Glucose

This is not usually found in the urine, but small amounts can be detected if the patient is unwell, or is on steroids. If there is a large amount of glucose, consider checking a blood glucose to rule out diabetes, and see if there is any other evidence of kidney problems.

Ketones

A by-product from the breakdown of fat when sugar stores cannot be used. These can be seen in patients who have not been eating, vomiting and in DKA. It is always worth checking the blood glucose in these patients, as its absence in hypoglycaemic patients should alert you to a potential metabolic disorder.

Bottom line: Seen during periods of vomiting or not eating. Always check a blood glucose.

Bilirubin

Excessive bilirubin that is not dealt with in the liver is excreted in urine. Thus the presence of bilirubin in the urine can be seen in conjugated hyperbilirubinaemia, and therefore a feature of liver disease. If the urine dipstick measures urobilirubin then this can be seen normally on a dipstick (normal to 1+). A high urobilirubin could suggest haemolytic disease, as it reflects unconjugated bilirubin.

Bottom line: Bilirubin – not normal. Urobilinogen – normal (in small amounts)

Specific Gravity

This measures how dilute your urine is by comparing the solubility if the urine to water. If <1.005 then the urine is very dilute – do they drink a lot of water? If not the kidney may be unable to concentrate the urine, there it would be wise to consider checking a serum sodium and assess the patient for features of diabetes insipidus.

A high specific gravity means the urine is concentrated, and suggests that the patient may be dehydrated. If they do not appear hydrated, then does the patient appear oedematous? This could suggest systemic disease

A list of causes of high specific gravity

Bottom line: compare to the patient’s hydration status

pH

The urine pH varies and is usually slightly acidic. It can be influenced by diet and medication. Usually, alkaline urine is a product of vegetarian diets and medication. It can also be present in UTIs caused by urea splitting organisms, such as Proteus and Pseudomonas. It is seen in renal tubule anomalies or if the patient has metabolic alkalosis. Urinary acidosis is seen with high protein diets and can reflect systemic acidosis (for example, DKA, diarrhoea and vomiting)

Bottom line: Not very useful on its own.

Urine dipticks infographics

Selected references

https://litfl.com/dipstick-urinalysis/

https://patient.info/treatment-medication/urine-dipstick-test

Yates A. Urinalysis: how to interpret results. Nursing Times. 2016 Jun 8;112(2):1-3.

https://geekymedics.com/urinalysis-osce-guide/

https://www.mayoclinic.org/tests-procedures/urinalysis/about/pac-20384907

https://www.nice.org.uk/guidance/cg54/chapter/Recommendations#diagnosis

https://www.clinicalguidelines.scot.nhs.uk/nhsggc-paediatric-clinical-guidelines/nhsggc-guidelines/emergency-medicine/haematuria-management-and-investigation-in-paediatrics/

Fernandes DJ, Jaidev M, Castelino DN. Utility of dipstick test (nitrite and leukocyte esterase) and microscopic analysis of urine when compared to culture in the diagnosis of urinary tract infection in children. Int J Contemp Pediatr 2017;5:156-60

Jeng-Daw Tsai, Chun-Chen Lin, Stephan S. Yang, Diagnosis of pediatric urinary tract infections, Urological Science, Volume 27, Issue 3, 2016, Pages 131-134

Tsai JD, Lin CC, Yang SS. Diagnosis of pediatric urinary tract infections. Urological Science. 2016 Sep 1;27(3):131-4.

May 10, 2021 3

UTI whizzdom – the next steps

Emergency / General paediatrics / Renal / Urology
Cite this article as:
Felicity Beal. UTI whizzdom – the next steps, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.32306

A 4-month-old baby presents with a temperature and urine microscopy suggestive of a urinary tract infection. He appears well and your plan is to discharge home on an oral antibiotic, whilst awaiting culture results. His mother asks you, “Does he need any other tests?”

Why does it matter?

Urinary tract infections (UTIs) are very common in children. Studies suggest that 6-8% of febrile, unwell children presenting to their GP have a UTI. Therefore it is important to carefully select which of these children need further investigations in order to identify those with underlying renal tract problems. It is estimated that up to 15% of children with a first UTI have evidence of scarring on follow up scans. If they are missed, these children may go on to develop hypertension and possible chronic kidney disease later in life.

Which children are more likely to get a UTI?

Before the age of 6 months, UTIs are more prevalent in boys. This is partly due to the increased chance of structural abnormalities within the urinary tract. Uncircumcised boys are particularly at risk, as bacteria on the foreskin are a reservoir for infection.

However, after 6 months of age, girls are at increased risk due to their shorter urethra and its proximity to the anus. This risk is increased again in females when they become sexually active.

Risk factors for UTIs

There are several other risk factors that increase the risk of developing a urinary tract infection. The main risk factor is something we see and manage on a daily basis, another really common presentation…constipation! If you haven’t yet read Chris Dadnam’s Conversations about Constipation post, now would be a great time to have a refresher as these two conditions go hand in hand.

As the colon and rectum fill with stool, the mass effect results in incomplete bladder emptying. This results in stasis of urine. Always ask about, and treat, constipation… If this is left unmanaged UTIs will continue to be a problem. 

After taking a good constipation history and examining the abdomen, it’s important you assess the spine looking for dimples, swellings, birthmarks or hairy patch lesions that can be associated with a neuropathic bladder. This should be followed by a lower limb neurological assessment. I think of this as running a bath after a hard day at work. You are unable to fully empty the tub afterwards but continue to add more bathwater to the tub every time… this will encourage infection to harbour. Recurrent UTIs may be the main presenting complaint in young children and should always prompt a review of the spine.

Foreign bodies such as intermittent or indwelling catheters also pose a risk. But it is essential to remember the last risk factor, not visible to the eye … namely urinary reflux.

Is this the same as vesico-ureteric reflux?

Yes. This is simply a term describing where, anatomically, the reflux occurs – from the bladder (vesico) to the ureters (ureteric). Urine flows back up from the bladder to the ureters causing a bidirectional flow of urine.

How vesico-ureteric reflux can cause a UTI

VUR can be primary, i.e. within a normal renal tract, or secondary, due to an abnormal renal tract – such as a neuropathic bladder. It is graded from 1 (mild) to 5 (severe.) Most mild to moderate reflux resolves by 5 years of age. However, surgery may be indicated if severe reflux is present, with worsening renal impairment or frequent pyelonephritis.

History and examination

As part of the history taking and examination, it is key to think about whether there could be underlying constipation, VUR or a neuropathic bladder. Asking about a family history of renal problems as well as considering antenatal renal scans is important to risk stratify for structural problems.

Ask about

  1. Constipation
  2. Urine flow
  3. Lower limb/back problems
  4. Antenatal renal abnormalities
  5. Family history of renal problems
  6. History of previous UTI/ fevers

Examine for

  1. Hypertension (complication)
  2. Poor growth
  3. Spine – for any spinal lesions
  4. Lower limb neurology
  5. Faecal masses
  6. Enlarged bladder / abdominal mass

What do we need to consider when further investigating UTIs?

NICE (the National Institute for Health and Care Excellence) ask the following three questions when considering a child’s risk of reflux and scarring:

How old is the child? Age is important. This may be a neonate or infant presenting with an infection as the first indicator of a possible underlying structural abnormality such as posterior urethral valves or VUR.

Is this an atypical UTI? 80% of paediatric UTIs are secondary to E.coli infection. An infection caused by an organism other than E.coli, or not responding within 48 hours of antibiotic therapy, is more unusual. Equally, if a child with a UTI looks unwell, has a palpable bladder, renal impairment or poor urine flow, your index of suspicion should be raised. These are uncharacteristic signs of a urinary tract infection.

Is this child having recurrent infections? Over 30% of children with UTIs will suffer from recurrent infections. Recurrent infections are defined as children who have either 2 or more upper UTIs (affecting the kidneys or ureters), 3 lower urinary tract infections (affecting the bladder or urethra) or 1 upper and 1 lower infection at any point up until the age of 16.

Investigations? Clear as M.U.D.

Key investigations to follow up children with a UTI
  • MCUG in 4 – 6 months
  • Ultrasound scan acutely or within 6 weeks
  • DMSA in 4 – 6 months

MCUG

An MCUG is a Micturating Cystourethrogram, which assesses for urinary reflux or obstruction. A catheter is inserted and radio-opaque contrast is administered via the catheter to fill up the bladder. X-rays are then taken during urination to see if urine is refluxing back towards the kidney.

Normal MCUG. Case courtesy of Dr Aditya Shetty, Radiopaedia.org. From the case rID: 27065
MCUG illustrating marked dilatation of the prostatic portion of the urethra consistent with posterior urethral valves. Case courtesy of Dr Andrew Dixon, Radiopaedia.org. From the case rID: 10432

DMSA

A DMSA scan is used to assess the function and location of the kidneys. An isotope that emits gamma rays is attached to ‘Dimercaptosuccinic acid’. This is administered via an intravenous cannula and is taken up by the kidneys a few hours later. If performed acutely it can show altered function consistent with pyelonephritis. In the UK, a DMSA scan is undertaken 4-6 months post-infection to assess for scarring.                       

A normal DMSA with equal isotope uptake in both kidneys. Case courtesy of Dr Yusra Sheikh, Radiopaedia.org. From the case rID: 69041

What does the guidance say?

In 2007, NICE published a guideline called “Urinary tract infection in the under 16s: diagnosis and management”, updated in 2018. When it comes to imaging, there are three main highlights.

1. Children under 6 months of age with a first typical UTI should have an ultrasound to assess for a structural cause. An MCUG is considered if this is abnormal.

2. All children with an atypical UTI, regardless of age, should have an ultrasound acutely. A DMSA is also performed if they are under 3 years of age to assess renal parenchyma. Children under 6 months are investigated more fully with an USS, DMSA and MCUG.

3. All recurrent UTIs require a DMSA scan within 4-6 months to assess for scarring.

This traditional approach for investigating children for reflux and scarring is safe yet adopts a different approach to imaging children with UTIs compared with other countries.

Controversial whizzarding….

The decision of who should be investigated further has caused great controversy. Different approaches are adopted around the world. This is due to conflicting evidence with clinicians balancing the risk of radiation, invasive imaging and cost with that of detecting children with an underlying congenital anomaly and preventing the development of chronic kidney disease.

There is conflicting data surrounding the risk factors for VUR in children with their first UTI. Ristola et al (2017) investigated risk factors for children with UTIs, finding the following 3 as the main risk factors for reflux: ultrasound abnormalities, recurrent infections and atypical infections. Interestingly, non-E. coli infections were the only statistically significant risk factor of infection recurrence.

Yılmaz et al (2016) were unable to identify risk factors associated with VUR, although did note that an abnormal renal scan at 6 months after the infection was closely related to the presence of VUR and recurrent UTIs.

In America, Canada, Poland and Italy, children up to 2 -3 years of age with their first UTI would be advised to have an ultrasound. The European Association of Urology advises every child presenting with a first UTI to be investigated with sonography. This is in comparison with the 6 month cut off advised by NICE, which is argued to be a more cost effective and risk stratified approach.

However, the American, Canadian and Italian guidelines do not investigate all children with recurrent UTIs as previously advised by the NICE guidance. Instead of all children with recurrent UTIs undergoing a DMSA scan, recent guidance suggests only performing a DMSA if there were concerns regarding an abnormal ultrasound or alternative diagnosis.

Therefore this makes me wonder, instead of investigating all children with recurrent UTIs, perhaps this decision should be made on an individual basis, using their ultrasound findings and considering risk factors.

How accurate are ultrasound scans in picking up VUR?

An ultrasound cannot exclude all cases of VUR as it is an observer-dependent investigation. Mahant et al (2002) reported low sensitivity of 40% and a specificity of 76% when diagnosing VUR, but the majority of these patients had lower grade reflux. There is now increasing awareness that low-grade reflux and mild scarring are unlikely to cause long term problems, therefore the argument presents itself: is there any benefit in investigating for them? Ultrasound scans are more likely to detect higher grade reflux and hence clinically significant cases, but further evidence is needed to support this approach.

The take homes

Some evidence suggests that children with ultrasound abnormalities or recurrent UTIS are at increased risk of complications from UTIs, regardless of their age or sex. There is no clear consensus on when to request a DMSA or MCUG but the latest evidence suggests that DMSA scans may not be necessary in all children with recurrent infections and a normal ultrasound scan. Clinicians should be aware of this existing controversy, weighing up the benefits and risks in order to make informed clinical decisions.

References

Craig J. Urinary tract infection: new perspectives on a common disease. Curr Opin Infect Dis 2001; 14 (3): 309–313.

Davis A, Obi B, Ingram M. Investigating Urinary tract infections in children BMJ 2013; 346 : e8654

Edlin RS, Shapiro DJ, Hersh AL, et al Antibiotic resistance patterns of outpatient pediatric urinary tract infections. J Urol2013;190:222–7.doi:10.1016/j.juro.2013.01.069

Kaufman J, Temple-Smith M, Sanci LUrinary tract infections in children: an overview of diagnosis and management BMJ Paediatrics Open 2019;3:e000487. doi: 10.1136/bmjpo-2019-000487

Mahant S, Friedman J, MacArthur C. Renal ultrasound findings and vesicoureteral reflux in children hospitalised with urinary tract infection. Arch Dis Child. 2002 Jun;86(6):419-20. doi: 10.1136/adc.86.6.419. PMID: 12023172; PMCID: PMC1762998.

Mori R, Lakhanpaul M, Verrier-Kones K. Diagnosis and management of urinary tract infection in children: summary of NICE guidance. Br Med J 2007; 335 (7616): 395–397.G

National Institute for Health and Care Excellence. Urinary tract infection in children: diagnosis, treatment and long-term management. Clinical guideline 54. London: NICE, 2007.

Newman DH, Shreves AE, Runde DP Pediatric urinary tract infection: does the evidence support aggressively pursuing the diagnosis?Ann Emerg Med2013;61:559–65.doi:10.1016/j.annemergmed.2012.10.034

O’Brien K, Edwards A, Hood K, et al Prevalence of urinary tract infection in acutely unwell children in general practice: a prospective study with systematic urine sampling. Br J Gen Pract2013;63:e156–64. doi:10.3399/bjgp13X663127

Okarska-Napierała M, Wasilewska A, Kuchar E Urinary tract infection in children: Diagnosis, treatment, imaging – Comparison of current guidelines. J Pediatr Urol2017;13:567–73.doi:10.1016/j.jpurol.2017.07.018

Ristola MT, Löyttyniemi E, Hurme T. Factors Associated with Abnormal Imaging and Infection Recurrence after a First Febrile Urinary Tract Infection in Children. Eur J Pediatr Surg. 2017 Apr;27(2):142-149. doi: 10.1055/s-0036-1572418. Epub 2016 Feb 8. PMID: 26855368.

Shaikh N, Craig JC, Rovers MM, et al. Identification of children and adolescents at risk for renal scarring after a first urinary tract infection: a meta-analysis with individual patient data. JAMA Pediatr2014;168:893–900.doi:10.1001/jamapediatrics.2014.637

Shaw KN, McGowan KL, Gorelick MH, Schwartz JS. Screening for Urinary Tract Infection in Infants in the Emergency Department: Which Test Is Best? Pediatrics. 1998;

Stein R, Dogan HS, Hoebeke P, et al Urinary tract infections in children: EAU/ESPU guidelines. Eur Urol2015;67:546–58.doi:10.1016/j.eururo.2014.11.007

Subcommittee on Urinary Tract Infection Reaffirmation of AAP clinical practice guideline: the diagnosis and management of the initial urinary tract infection in febrile infants and young children 2-24 months of age. Pediatrics 2016;138:e20163026.doi:10.1542/peds.2016-3026

Yılmaz S, Özçakar ZB, Kurt Şükür ED, Bulum B, Kavaz A, Elhan AH, Yalçınkaya F. Vesicoureteral Reflux and Renal Scarring Risk in Children after the First Febrile Urinary Tract Infection. Nephron. 2016;132(3):175-80. doi: 10.1159/000443536. Epub 2016 Feb 23. PMID: 26901769.

          

                                         

March 22, 2021 0

Nephrotic syndrome

Renal
Cite this article as:
Rachael Kermond. Nephrotic syndrome, Don't Forget the Bubbles, 2021. Available at:
https://doi.org/10.31440/DFTB.31540

Who, when and what…

Nephrotic syndrome is the most common glomerular disorder of childhood, affecting 1-7 children in 100,000 per year.  It most typically affects children aged 2- 12 years of age and is characterized by proteinuria, hypoalbuminaemia and oedema.

Why it happens…

The villain of nephrotic syndrome is the glomerular filtration barrier (GFB).  If we peer back at our textbooks, we remember the GFB is composed of two cells, the capillary endothelial cells and the podocytes separated by the glomerular basement membrane.  The GFB is responsible for the filtration of water and small solutes but the retention of albumin.  Defects in this GFB result in increased permeability to albumin and the subsequent proteinuria that defines nephrotic syndrome. 

The Glomerular Filtration Border

Idiopathic nephrotic syndrome (INS) is the most common cause of nephrotic syndrome in children.  The aetiology is unclear however it could be related to circulating factors that, via immune mechanisms, alter the podocyte function and thus the GFB.  The underlying histopathology of INS is minimal change disease (MCD) and less frequently focal segmental glomerulosclerosis (FSGS) which carries a poorer prognosis.

Other, less common causes include genetic mutations (with up to 50 genes affecting various components of the GFB identified to date), membranous glomerulopathy and glomerulonephritis (such as systemic lupus erythematous).

How it presents…

Children often present with a history of intermittent periorbital or pedal oedema.  It is not commonly diagnosed until the child develops gross oedema with scrotal or labial oedema, ascites and even pleural effusions which prompts presentation.

Other potential presenting features include sepsis, cellulitis related to oedema, spontaneous bacterial peritonitis and complications of a prothrombotic state such as venous sinus thromboses.  

How we investigate it…

It’s important to confirm proteinuria with a urine protein:creatinine ratio.  Other investigations include a full blood count to evaluate for evidence of haemoconcentration, biochemistry to assess for hyponatraemia, acute kidney injury and serum albumin levels and a urinary sodium to assist in determining the intravascular fluid status of the patient.

Consideration of an immunologic assessment (ANA, complements) should occur if a patient presents with other systemic symptoms or haematuria.  Finally, the patient’s immune status to varicella-zoster is important as it will guide prophylaxis if future exposure occurs.

How we treat it…

There are two main arms to the treatment of nephrotic syndrome.  Acutely, the management of severe oedema and chronically, the treatment of the disease for which the basis is corticosteroids.

Management of acute presentation:

When assessing oedema in a nephrotic patient, it’s important to evaluate the intravascular fluid status of the patient.  Hypotension, cool peripheries, elevated creatinine and a low urinary sodium are all features consistent with intravascular depletion.  Whereas those who are oedematous, well-perfused with hypertension and a urinary sodium > 10mmol/L are likely well hydrated.

Management includes a strict fluid balance with a daily weight, a diet low in salt, the introduction of a fluid restriction (unless there is evidence of intravascular depletion) and consideration of IV albumin with frusemide.

If indicated, 1g/kg (5ml/kg) of 20% albumin should be given over 4-6 hours with 1mg/kg IV frusemide dose either halfway through and/or on completion of the infusion (depending on the patient’s fluid status).  Those who have evidence of hypervolaemia may be treated with IV frusemide alone. However, this is a short term strategy and they should be closely monitored for evidence of hypovolaemia.  

Another component of the acute management is consideration and treatment of the potential complications including sepsis, cellulitis, spontaneous peritonitis and thrombotic sequelae. 

Long term management:

Whilst oedema is being treated it is important to instigate the mainstay of nephrotic syndrome therapy, prednisolone.  The initial dose is 60mg/m2 for 4-6 weeks followed by a weaning course (alternate daily dosing) for up to 2 months.  Previously, this initial course had been as long as 6 months.  There is consistent data in the literature that demonstrates that this shorter regime is non-inferior and leads to a reduction in the side effects of steroids, particularly on growth.

The initial presentation is an invaluable opportunity to provide support to these families who are now presented with a chronic medical illness.  This is facilitated by intensive education, dietician review and social work (or equivalent) input.

Education:

  • A dedicated consult explaining the diagnosis, management, ongoing monitoring requirements and prognosis.
  • Provide demonstration of urine dipsticks as this will be required daily for at least a year post-diagnosis and even longer if the patient frequently relapses.
  • Supplement with written information and a diary for the family to record urine results, weights and steroid dose.  

Dietetics:

  • A dietetic consult to provide advice around a low salt diet and fluid restriction.  
  • These restrictions are required whilst the patient is nephrotic and are often reinstated during relapses.
  • Education is also provided regarding a healthy balanced diet to avoid significant weight gain on high dose steroids. 

Pastoral Care

  • The diagnosis of nephrotic syndrome is often met with considerable anxiety and distress from families who now face a chronic disease for their child.
  • A social worker or equivalent support structure is important to assist in acknowledging these concerns and anxieties.
  • Provision of information regarding potential financial support is also considered.
  • Preventative measures against complications of nephrotic syndrome are equally important.

Gastritis

  • Gastritis is a common complication of high dose steroids and can present with epigastric pain or generalized abdominal pain.
  • Acid suppression medications such as a proton pump inhibitor (PPI) are recommended whilst children are on high dose steroids. 
  • These can be ceased when the child moves to alternate-day steroid therapy.

Infection

  • Penicillin V at 12.5mg/kg BD should be considered for those children who present with ascites as prophylaxis for spontaneous bacterial peritonitis.  This therapy is continued until the patient remits (i.e. no longer proteinuric).
  • If a child with nephrotic syndrome has contact with a known source of VZV, subcutaneous immunoglobulin should be administered

Immunisations

  • Live vaccines are contraindicated whilst the child is nephrotic and/or on high dose steroids
  • Ensure yearly influenza vaccine.
  • Children who frequently relapse or have persistent nephrotic syndrome qualify for additional pneumococcal vaccine. 

The use of aspirin and other anti-thrombotic agents have largely been abandoned given the risks of these therapies.  The likelihood of thrombosis is significantly reduced once the child’s oedematous state is appropriately managed  

What happens next…

90% of children respond to steroid therapy within 4-6 weeks (i.e. steroid-sensitive).  Remission is defined as a negative/trace urine dipstick for three consecutive days.  There are a small proportion of children who will not remit in this time period, referred to as steroid-resistant.  These children require consideration of a renal biopsy and/or genetic testing (such as rapid genomic sequencing) thus warrant a referral to a paediatric nephrologist.

80% of children with nephrotic syndrome will relapse, often in the context of a concurrent illness.  This is the basis for ongoing urine dipstick testing.  This will detect a relapse prior to the child becoming oedematous and so may avoid further hospital admission.

Some children will demonstrate steroid-dependence or become frequent relapsers (i.e. ≥2 relapses in the first 6 months following diagnosis or ≥4 in any 12 month period).  These patients, in addition to the steroid-resistant group, should be referred to a nephrologist for ongoing management.

Finally, approximately 10% of patients with nephrotic syndrome will continue to relapse in their adult life.  

The bottom line…

  • Nephrotic syndrome is the most common glomerular disorder of children
  • Acute management involves the treatment of oedema and potential complications of the nephrotic state
  • Long term management is with prednisolone 
  • Equally important at diagnosis is education, social support and dietetic review 
  • Referral to nephrology is required if a child demonstrates any of the following
    • Steroid resistance
    • Steroid dependence
    • Frequent relapses
    • Atypical presentation (e.g. microscopic haematuria, acute kidney injury etc…)

References

  1. Metz D, Kausman J. (2014) Childhood nephrotic syndrome in the 21st century: what’s new? Journal of Paediatric and Child Health, 51, 497-504.
  2. Hahn D, Samuel S, Willis N, Craig J, Hodson E. (2020). Corticosteroid therapy for nephrotic syndrome in children. Cochrane database of systematic reviews, accessed 11 October 2020, doi.org/10.1002/14651858.CD001533.pub6.
  3. Hodson E, Wong S, Willis N, Craig J. (2016) Interventions for idiopathic steroid-resistant nephrotic syndrome in children. Cochrane database of systemic reviews, accessed 11 October 2020, doi.org/10.1002/14651858.CD003594.pub5.
  4. Ding W, Moin S. (2012) Current concepts of the podocyte in nephrotic syndrome. Kidney research and clinical practice, 31, 87-93.
  5. Bensimhon A, Williams A, Gbadegesin R. (2018) Treatment of steroid-resistant nephrotic syndrome in the genomic era. Paediatric Nephrology, 34, 2279-2293. https://doi.org/10.1007/s00467-018-4093-1
  6. McCaffrey J, Lennon R, Webb N. (2016) The non-immunosuppressive management of childhood nephrotic syndrome. Paediatric Nephrology, 31, 1383-1402 doi: 10.1007/s00467-015-3241-0

January 18, 2021 0

Haemolytic Uraemic Syndrome

Emergency / Infectious Diseases / Intensive Care / Renal
Cite this article as:
Jennifer Watt. Haemolytic Uraemic Syndrome, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.26233

What is HUS?

Haemolytic Uraemic Syndrome is a combination of findings which involves the triad of:

  • Microangiopathic haemolytic anaemia with red blood cell fragmentation on blood film
  • Acute renal failure
  • Thrombocytopenia

 What causes HUS?

About 90% of cases follow an infection, most commonly with entero-haemorrhagic E. Coli (EHEC). Other infective causes to be considered include Shigella and Streptococcus pneumoniae.

These infections are commonly contracted by the ingestion of contaminated food or water sources. In the US and UK, E. Coli 0.157 forms part of the natural intestinal microflora of cattle and sheep, therefore infection can be caused by direct contact with animal faeces. This can take place at farms or petting zoos, or via undercooked contaminated meat or dairy products.

The other 10-15% of cases represent atypical HUS and are due to a variety of causes, which will not be discussed here.

How do children present?

In children infected with EHEC about 10-15% of them will go on to develop HUS.

The common presentation includes bloody diarrhoea +/- cramping abdominal pain, fever and/or vomiting. The average onset of HUS after development of diarrhoea is about 7-10 days, with children under the age of 5 at highest risk.

Dependent on the extent of HUS progression, children may present with pallor, oedema, lethargy, or reduced urine output.

How to approach the examination

As with any unwell child, an A to E assessment is critical to rule out any immediate, life threatening complications.

Specific attention should be paid to assessing their fluid status, especially for evidence of dehydration.

*Although they may be oedematous, it is important to assess if they are intra-vascularly dry.

Things to examine for:

  • Prolonged capillary refill time
  • Observations: Tachycardia; hypotension or hypertension
  • Are they are cool peripherally?
  • Assess fontanelle tension (if applicable)
  • Dry mucus membranes/reduced skin turgor
  • Oedema (common locations in children include lower limbs, sacral and peri-orbital)

Is there evidence of neurological sequelae?

  • Irritable/restlessness
  • Confusion
  • Reduced GCS

Key investigations to perform

A. Initial blood samples:

  • Full blood count with blood film to assess for RBC fragmentation
  • Coagulation
  • Group and Save +/- cross match if haemoglobin low
  • Biochemistry: U&Es, calcium, phosphate, magnesium, bicarbonate
  • Glucose
  • CRP
  • Liver function including albumin
  • Amylase/Lipase (hospital dependent)
  • LDH
  • Blood gas
  • Blood cultures

B. Stool MC&S + E. Coli PCR

C. Urinalysis + MC&S

How to approach the management of HUS

Management should always be discussed with your local paediatric nephrologist in order to individualise/optimise management.

This is a generalised framework for the approach to management. Treatment involves supportive therapy to allow time for the infection to clear and the HUS process to cease.

1. Fluid Management:

  • IV access
  • Assess fluid status
  • Monitor for electrolyte disturbances and correct as per local guidelines
  • Daily weight, In/Out fluid balance, close monitoring of patient observations

*Fluid rehydration should be administered cautiously and in the setting of oliguria/anuria and oedema, fluids given should not exceed insensible loss + urine output.

*Evidence has shown that children presenting to hospital with dehydration in the prodromal phase of EHEC-induced HUS have a higher risk of developing an oliguric AKI and the requirement for dialysis. The administration of isotonic fluid in this phase has shown to be nephroprotective. 

2. Hypertension:

  • Can be secondary to fluid overload or as a result of the HUS process
  • Trial of diuretics or if receiving dialysis, fluid can be offloaded
  • If unresponsive to diuretics, consider a vasodilator (For example, amlodipine/ nifedipine *hospital dependent)

3. Anaemia:

  • Target Haemoglobin: 70-100g/L
  • Avoid excessive transfusion due to the associated risk of development of hyperkalaemia or fluid overload

4. Thrombocytopenia:

  • Consideration for platelet transfusion if platelets <10 x109
  • If undergoing surgery may require platelets > 50 x 109

5. Abdominal pain/vomiting:

  • Secondary to colitis
  • Regular paracetamol for pain relief
  • Avoid opiates if possible due to constipating side effects

*NSAIDS like Ibuprofen should not be prescribed*

6. Nutrition:

  • All patients should be reviewed by a dietician
  • NG tube and feeding regime

7. Dialysis (Peritoneal Dialysis or Haemodialysis) Indications:

  • Intractable acidosis
  • Diuretic resistant fluid overload
  • Electrolyte abnormalities Hyperkalaemia
  • Symptoms of uraemia

In children with HUS, peritoneal dialysis is the preferred treatment option as it is a gentler form of dialysis.

Haemodialysis is indicated for children with severe colitis, severe electrolyte abnormalities and those with neurological complications.

 HUS Complications

  • AKI:  Oliguria/anuria; hyperkalaemia; hypertension
  • Neurological: Irritable, confusion, seizures
  • Bleeding Risk
  • Cardiac: Hypertensive cardiomyopathy/myocarditis
  • Gastrointestinal: Severe colitis with bleeding/perforation
  • Pancreatitis
  • Pulmonary oedema

Selected references

Mayer CL, Leibowitz CS, Kurosawa S and Stearns-Kurosawa DJ. Shiga Toxins and the Pathophysiology of Hemolytic Uremic Syndrome in Humans and Animals. Toxins (Basel). Nov 2012. [Cited June 2020]; 4 (11): 1261-1287. doi: 10.3390/toxins4111261

Kausman. J 517 Haemolytic uraemia syndrome. Royal Hospital for Children- Nephrology. Dec 2013. [Cited June 2020]; Available from:  https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3509707/

Hughes D. Management and investigation of bloody diarrhoea and haemolytic uraemic syndrome [draft].  GG&C Paediatric Guidelines- Kidney Diseases. Oct 30 2019. [Cited June 2020]; Available from: https://www.clinicalguidelines.scot.nhs.uk/ggc-paediatric-guidelines/ggc-guidelines/kidney-diseases/management-and-investigation-of-bloody-diarrhoea-and-haemolytic-uraemic-syndrome-draft/

Balestracci A et al. Dehydration at admission increased the need for dialysis in hemolytic uremic syndrome children. Pediatr Nephrol. 2012. [ Cited June 2020];27: 1407-1410. Doi: 10.1007/s00467-012-2158-0

Scheiring J. Andreoli SP. Zimmerhackl LB. Treatment and outcome of Shiga-toxin-associated hemolytic uremic syndrome (HUS). Ped Neprhrol. 2008. [Cited June 2020]; 23: 1749-1760. Doi: 10.1007/s00467-008-0935-6

Grisaru Silviu. Management of hemolytic-uremic syndrome in children. Int J Nephrol Renovasc Dis. 2014 [Cited June 2020]; 7: 231-239. Doi: 10.2147/IJNRD.S41837.

August 19, 2020 0

COVID19 and ACE inhibitors

COVID / Renal
Cite this article as:
Cathy Quinlan. COVID19 and ACE inhibitors, Don't Forget the Bubbles, 2020. Available at:
https://doi.org/10.31440/DFTB.24225

Why do my patients keep asking me about ACE inhibitors and COVID-19?

Hypertension is a common problem affecting 3.5% of children and adolescents and correlating with increased cardiovascular risk in young adults. Common first-line therapies include angiotensin converting enzyme inhibitors (ACEi), such as ramipril, lisinopril and enalapril.

Over the last few weeks, a storm has erupted over the use of ACEi with the suggestion that they could be associated with severe COVID-19. A statement by the European Society of Cardiology, was quickly followed by most national hypertension societies, including the American Society of Pediatric Nephrology and the High Blood Pressure Research Council of Australia, recommending the continuation of ACEi in patients with COVID-19. 

 

How are ACEi linked with COVID-19?

The COVID-19 literature to date has suggested increased mortality for adults with hypertension and for those with diabetes, a patient cohort frequently treated with ACEi. Although medication use has not been reported in patients with COVID-19, a letter to the Lancet postulated that the use of ACEi could be implicated in the increased mortality rate described in patients with hypertension. 

Human coronoviruses, such as SARS-CoV-2, gain entry to the cell through ACE2 which is expressed by epithelial cells of the lung and kidney. Thus a treatment that increases the expression of ACE2 at the cell surface could increase the severity of COVID-19 infection. There is animal evidence that circulating ACE2 levels are increased by treatment with ACEi. But also conflicting evidence in humans showing no association between circulating ACE2 levels and the use of ACEi. 

Interestingly, there is clinical data to suggest that ACE inhibition may actually be a potential therapy for viral pneumonia. Though it should be noted that this is confined to retrospective, observational data, clinical trials are underway to examine the use of recombinant ACE2 and losartan in adults with COVID-19, highlighting that the use of ACEi in patients with COVID-19 is not clearcut. 

 

How does this impact our patients?

A growing body of evidence, summarised by the DFTB team here, shows that children are at much less risk of severe disease than adults. Indeed, only 1 of 731 patients with confirmed COVID-19 infection in the largest study to date, had clinically critical disease. The data on ACEi in COVID-19 is inconclusive and pending further data there is no evidence to change anti-hypertensive management in children at this point in time. 

 

The Bottom Line

There is currently no evidence, in children or adults, to support changing blood pressure medication due to the COVID-19 pandemic.

 

I want to know more!

If you want to read more about HTN then please review the 2017 Hypertension guidelines from the American Academy of Paediatrics.

If you’d like to know more about ACE2, hypertension, and COVID-19 then check out the dedicated ACE2 NephJC page.

For up to date reviews of the COVID-19 literature as it pertains to the kidney along with management guidelines check out the COVID-19 NephJC page. 

If you are aware of resources that you think would be useful to the nephrology community then please tag it with #CoronaKidney and they will be added to the page after they are reviewed. 

 

March 23, 2020 1

Renal Failure

Cardiology / Intensive Care / Renal
Cite this article as:
Marc Anders. Renal Failure, Don't Forget the Bubbles, 2013. Available at:
https://doi.org/10.31440/DFTB.3719

Definition: acute kidney injury (AKI) is failure of the kidneys to regulate electrolyte, acid-base and fluid homeostasis adequately with concomitant reduction in glomerular filtration rate (GFR). pRIFLE (paediatric Risk, Injury, Failure, Loss, End-Stage Criteria).

Chronic renal failure: hyperfiltration, estimated creatinine clearance <75 ml/min/1.73m2 , hypertension, microalbuminuria.

Read more
September 9, 2013 0

Diabetes Insipidus

Endocrinology / Intensive Care / Renal / Surgery
Cite this article as:
Tessa Davis. Diabetes Insipidus, Don't Forget the Bubbles, 2013. Available at:
https://doi.org/10.31440/DFTB.3030

A 5-year-old girl is on the ward following resection of a craniopharyngioma.  The nurses call you because her urine output has increased dramatically over the last few hours.  You check her sodium and it’s 150.

Is your brain hurting just thinking about it?

 

Bottom Line

  • Suspect diabetes insipidus if there is polyuria, polydipsia in the presence of a high serum Na and low urinary Na
  • Manage with vasopressin and appropriate hydration
  • Watch for hyponatraemia following the commencement of treatment
  • This can be a life-long condition and ease of management will depend on whether the patient has an intact thirst centre

 

What is DI?

In diabetes insipidus, the body produces no (or very little) anti-diuretic hormone.  This means that the patient cannot concentrate the urine and ends up with dehydration and electrolyte imbalance.

 

What causes it?

ADH is a hormone that regulated fluids and sodium retention.

In cranial DI the pituitary does not properly signal for the release of ADH when needed (i.e. when dehydrated) and so there is no ADH to instigate fluid retention.  Due to dehydration, the body then tries to retain sodium.

Cranial DI causes include: surgery (trans-sphenoidal); traumatic brain injury; idiopathic; autoimmune; tumours (suprasellar, lung, breast, lymphoma, leukaemia); hypoxic brain injury; brain stem death; profound hyponatraemia; radiotherapy; drugs – amiodarone, lithium; inflammatory conditions – sickle cell, sarcoid, Wegener’s, histiocytosis X; infections – TB, abscess, encephalitis, meningitis; vascular disease – CVA, SAH, Sheehan’s syndrome.

In nephrogenic DI, ADH is being produced but the kidneys are not responding to it.   This is a different condition and will not be dealt with in this post.

How can I recognise it?

The symptoms of DI can include polyuria, polydipsia and dehydration or weight loss.

In some patients, the thirst centre is not intact and so they will no have symptoms of polydipsia.

 

Biochemical abnormalities

  • Urine output >4ml/kg/hr for 2 hours
  • Serum Na>145
  • Osmolality: serum >295 mOsmol/kg H2O And urine <450 mOsmol/kg H2O
  • Weight loss of >5%

Additional studies such as plasma ADH, urine specific gravity and a water deprivation test can assist with diagnosis. Urine specific gravity is a particularly handy test as it can be done there and then without going to the lab.

 

  • Water deprivation test

  • This test aims to check if the kidneys can concentrate urine in the presence of ADH
  • The patient is fluid deprived for 8 hours or until 5% of body weight is lost
  • Measure plasma osmolality every 4 hours. and urine volume and osmolality every 2 hours.
  • After the 8 hours, the patient is given IM vasopressin unless there is a clear indication of DI prior to this
  • urine and serum osmolality are checked over the following 4 hours
  • In cranial DI the urine osmolality will initially be low (<300 mmol/kg) and after vasopressin it will rise to >800
  • In nephrogenic DI giving the vasopressin will not make any difference to the osmolality

 

What is the treatment?

Management in ICU

If the patient has a high serum Na, high urine output and low urine osmolality in the post-op period, treatment should be considered (usually in discussion with the endocrine team).

Treatment is based around a combination of rehydration and vasopressin.

Vasopressin can be given IN, orally or IV.

The aim is to keep the Na at 135-140.  If the Na>150 the amount of vasopressin should be increased.

The other aim is to maintain hydration and a normal urine output (target 2-3 mls/kg/hr).

Be careful of hyponatraemia from over-treatment and also of bringing the sodium down too fast (this can cause cerebral oedema).

If the Na<135 then either stop the vasopressin or give some hypertonic saline.  Consider fluid restriction or frusemide if the Na continues to fall and is <130.  These patients can have seizures due to hyponatraemia post commencement of vasopressin if it’s not tightly monitored.

 

Calculating sodium replacement

(Target sodium – current sodium) x 0.6 x weight = mmol Na required to reach target

 

Sodium content of fluids

[wpsm_comparison_table id=”9″ class=”center-table-align”]

Ongoing DI management

Daily serum electrolytes and osmolality, and daily urine osmolality are required until stable.

Make sure sodium is above 145 mmol/L prior to administration of vasopressin.

Should have 1-2 hrs of diuresis (greater than 4ml/kg/hour) prior to administration of next dose to avoid hyponatraemia.

Patients should be weighed daily and keep a strict fluid balance chart.

 

What is cerebral salt wasting (CSW)?

This is rare but can occur following cranial surgery.

It causes polyuria and dehydration but with high urinary sodium (i.e. hyponatraemic dehydration).

The urine:serum osmolality ratio will be greater than 1.

CSW is managed with fluid replacement and salt replacement of urinary sodium losses (as guided by the serum sodium).

What’s the prognosis?

DI can be transient or permanent.

Pratheesh et al (2013) did a retrospective analysis of 102 children who were status post removal of craniopharyngioma (and compared them to adults)

  • DI was more common post-op in children than adults (80% v 63%)
  • Triphasic response (fluctuating serum sodium levels) was more common in children
  • Children had a higher incidence of permanent DI (55.6%)

 

Selected references

Diabetes insipidus, Royal Children’s Hospital (Melbourne)

Diabetes insipidus, Medscape

Pratheesh R, Swallow DM, Rajaratnam S, Jacob KS, Chacko G, Joseph M, et al. Incidence, predictors and early post-operative course of diabetes insipidus in paediatric craniopharygioma: a comparison with adults. Childs Nerv Syst. 2013;29(6):941-9.

How to do the water deprivation test

September 9, 2013 2

Microscopic haematuria

General paediatrics / Renal
Cite this article as:
Ben Lawton. Microscopic haematuria, Don't Forget the Bubbles, 2013. Available at:
https://doi.org/10.31440/DFTB.2916

A previously well 3-year-old girl presented to your ED with a history of fever. You have confidently diagnosed otitis media and are just about to discharge the child when the nurse mentions a urine was requested at triage and has come back positive for blood.

The nurse asks you what it means if the girl has blood in her urine….

The Bottom Line

  • With a urine dipstick that is positive for blood, the first thing to do is establish whether the finding is real (by microscopy).
  • Remember to look for UTI, hypertension, proteinuria and concerning family history
  • In the absence of red flags on history and examination, no investigations beyond microscopy are required until the microscopic haematuria has proved to be persistent.

What does this finding represent?

Microscopic haematuria is a common finding in the setting of febrile illness. It can be caused by many benign phenomena including adenovirus, ibuprofen, antibiotics including penicillin and indeed by fever itself.

There is always a concern that haematuria represents significant underlying renal pathology but in this circumstance, the risk is extremely small.

What further assessment should you perform and what are you looking for?

Clinical examination and urine microscopy are sufficient at this stage. The following table outlines the major things you should be looking for. There are more sensitive and specific ways of searching for all these findings but in this context, underlying renal disease is pretty unlikely so clinical assessment alone is good enough for now.

The key things to remember are to check for hypertension, proteinuria, UTI and a family history of renal failure.

FindingSuggestive of
Failure to thrivechronic disease process
WTU for proteinglomerulonephritis
WTU for leucs/nitriteUTI
FH renal failureany hereditary nephropathy
FH deafnessAlport syndrome
FH renal stonesfamilial hypercalciuria
Hx infection (2 weeks ago)post strep GN
Hx infection (1-2 days ago)TBMN/IgA nephropathy
bruises/bleedingbleeding diathesis
loin massesWilm’s tumour
oedemanephrotic syndrome
hypertensionnephritis

If this is all normal the only investigation required at this stage is urine microscopy and culture to confirm and quantify the presence of blood and determine if the cells are dysmorphic (suggesting a glomerular source of bleeding), This is also the definitive test for a UTI.

Any positive findings from the list above should prompt more sensitive/specific investigation.

 

So the history, exam and urine microscopy was normal, can I forget about the haematuria?

No, although significant renal disease is unlikely the child should be referred back to their GP for a repeat urinalysis in 2-4 weeks when they are well. If the haematuria has resolved at that time then no further action is required. Persistent haematuria will require further investigation.

 

So what proportion of kids with microscopic haematuria actually have significant renal disease?

A large study where urinalysis was performed in asymptomatic school children to evaluate its suitability as a screening tool for occult renal disease found the following:

  • Children screened – 7 million
  • Abnormal UA – 1044
  • Isolated haematuria – 719 (of 1044)
  • Biopsy performed (indications for biopsy = severe proteinuria, hypertension, abnormal renal function of a family history of renal disease) – 52
  • Thin glomerular basement membrane nephropathy (benign condition) on biopsy – 33
  • Other defined pathology on biopsy – 16

In other words of 719 children with isolated haematuria, 16 went on to have proven renal disease that warranted further management.

This was a population of well children and you can imagine that in a population of febrile kids, with the benign reasons for having haematuria outlined above, the proportion of kids with significant renal disease as a cause of their microscopic haematuria would be even smaller.

 

Does a positive dipstick mean there is definitely blood in the urine?

No, false positives on a dipstick can result from haemoglobinuria (e.g secondary to haemolysis) or myoglobinuria. It is also worth remembering that blood in the urine may originate from the vagina or rectum and some causes (e.g. anal fissure) may not be immediately evident on exam). Several things have been reported to cause a red tinge to the urine that may be mistaken for blood.

The following can all cause the appearance of gross haematuria but they should not cause a dipstick to read positive:

  • Drugs – chloroquine, ibuprofen, iron, sorbitol, nitrofurantoin, phenazopyridine, phenolphthalein
    Foods – beets, blackberries, food colouring metabolites
    Other – bile pigments, homogentisic acid, melanin, methemoglobin, porphyrin, tyrosine, urates

Microscopy should be able to confirm that the blood is for real.

 

References

McTaggart S. Childhood Urinary Conditions. Aust Fam Phys 2005; 34:937-41.

Park YH, Choi JY, Chung HS, et al. Hematuria and proteinuria in a mass school urine screening test. Pediatr Nephrol 2005; 20:1126–1130.

Quigley R. Evaluation of hematuria and proteinuria: how should a pediatrician proceed? Current Opinion in Pediatrics 2008, 20:140–144.

Rees L, et al. Oxford Specialist Handbooks in Paediatrics: Paediatric Nephrology, Oxford University Press. 2007. p18-19.

September 5, 2013