Blood in the water

1 Flares Twitter 0 Facebook 0 Google+ 0 LinkedIn 1 Email -- Filament.io 1 Flares ×

 

Tommy is a well looking 3 year old boy who’s concerned parents have brought him to your ED after passing what looked like blood in his urine. The Triage nurse has provided them with a urine jar and sure enough, tommy has filled it with something that looks a bit like pinot noir.

 

Is everything that glitters actually gold?

The first job is to make sure it is indeed blood that is causing the discolouration of the urine. While the beetroot sandwich Tommy had for lunch may be an obvious confounder, sometimes the iron supplement he is taking or the blackberries in the smoothie he shared with dad at the mall evade parental recollection. Dipstick testing is close to 100% sensitive and specific for blood. False positives can come from haemoglobinuria or myoglobinuria but if the dipstick is negative for blood then it’s worth asking lots of questions about diet and medication. Common culprits include beets, blackberries, rhubarb, food colouring, some antibiotics (rifampicin, metronidazole, nitrofurantoin), iron and salicylates. This list is not exhaustive so any new medications are worth checking.

Where should I look first?

In contrast to microscopic haematuria, haematuria that is visible to the naked eye (referred to as “gross” or “macroscopic” haematuria) will have an identifiable cause the majority of the time. The big distinction to make is between glomerular bleeding (i.e that coming from the kidney), and bleeding further down the urinary tract. Urine from glomerular bleeding is classically described as tea or cola coloured while that arising further downstream will be more red than brown. This is a bit subjective and probably should not be relied upon. More accurate is microscopy of the urine where dysmorphic red cells suggest the kidney is letting them through and normal red cells are more likely to have come from damaged mucosa somewhere on the way out.

What else can the dipstick tell me?

The presence of protein is significant. Proteinuria suggests the kidney itself is damaged and concerted efforts must be made to find out how. Haematuria alone may cause a dipstick to read up to 2+ for protein but this should be better defined by sending the urine for a protein:creatinine ratio which will much more accurately quantify the loss. Leucs and particularly nitrites suggest a urinary tract infection as the cause. This should be confirmed with microscopy and culture and can then be treated according the usual UTI protocols.

What should I ask about in the history?

Glomerular disease typically doesn’t hurt so loin pain suggests a non-glomerular cause such as UTI or a kidney stone. In the textbooks post-infectious glomerulonephritis is preceded by a sore throat or skin infection 10-14 days earlier, this is classically but not always caused by strep and in real life the history of preceding illness is absent in about 20% of cases. Recent history of diarrhoea, particularly bloody diarrhoea, is concerning for Haemolytic-Uraemic Syndrome. Non-renal symptoms such as rashes, bruising or joint pain may suggest a rheumatological cause like Heinoch-Schonlein Purpora (HSP) or rarely Lupus (SLE). Idiopathic Thrombocytopaenic Purpora (ITP) may present with a petechial rash and haematuria.

Apples often fall close to trees in renal disease so explore the family history carefully. Anyone having been on dialysis is a big red flag, as is deafness (which is associated with Alport’s syndrome). A family history of kidney stones may be the marker of familial hypercalciuria. Other people having been investigated for haematuria without any obvious consequences is reassuring in suggesting benign familial haematuria (aka thin basement membrane disease). Finally ask about holidays, partly because its nice to take an interest in your patients, but mostly because schistosomiasis and tuberculosis are important causes of haematuria in some parts of the world and if you don’t look, you won’t find them.

What am I looking for on exam?

Oedema and hypertension are two consequences of renal disease that you will not want to miss. Make sure the BP measurement is accurate, taken with the correct sized cuff and with the child sitting down and relaxed. Remember that scrotal oedema can be mistaken for hydrocoeles, particularly in small children and parents are usually better judges of whether or not their kid’s face looks puffy than we are, so ask them.   Lumps in the abdomen may represent polycystic kidneys, hydronephrosis or, rarely, a Wilm’s tumour. If you find a lump, ultrasound it. Systemic features of diseases with renal manifestations may also be relevant. Rashes typical for HSP, ITP or SLE, joint pain and fever will all help steer your diagnostic ship.

What else can I do with the urine?

Having dipped it and sent it for microscopy, culture and a protein: creatinine ratio the last key test on the urine is a calcium:creatinine ratio. Hypercalciuria is the most common non-glomerular cause of macroscopic haematuria. The familial form is benign though associated with an increased risk of kidney stones. This risk can be minimised by promoting good hydration and a low sodium diet.

What blood tests do I need to do?

Unless you have clearly established a benign cause on examination of the urine blood tests will be required. FBC will identify ITP or HUS or associated anaemia and may suggest infection. U and Es will check renal function and identify electrolyte abnormalities. Calcium and Phosphate abnormalities are associated with chronic renal disease while hyperkalaemia is a real danger in renal failure. ASOT and antiDNAase B are associated with recent streptococcal infection and together with a low complement (C3) level suggest post-infectious glomerulonephritis. Coagulation profile may be relevant both as a cause of haematuria and can be affected by significant protein loss in the urine as some of the lost proteins are those that are involved in the coagulation cascade.

Investigation for schistosomiasis or tuberculosis can be limited to those with a relevant travel history.

Do I need any imaging?

USS is generally low yield but given the lack of pain or radiation involved and the significance of abnormal findings (most notably Wilm’s tumour) this is something that is worth doing but not really something that you need to call an ultrasonographer in at 2 am for.

What about other tests?

Biopsy is usually reserved for steroid resistant glomerulonephritis or circumstances where there is some other complicating factor. Cystoscopy is rarely indicated in paediatrics.

What do I do with Tommy now?

Everyone needs follow up. If you have identified a benign pathology such as an uncomplicated UTI it is reasonable to arrange follow-up with the GP. If the child is well and has no red flags, no protein in their urine and normal blood pressure urgent outpatient referral may be appropriate. If the child is hypertensive, losing protein in their urine or red flags in their personal or family history then discussion with a specialist before discharge is required. These children will likely need admission but in many cases a management plan and robust follow up arrangements will be adequate provided the in-patient specialist has been involved in the conversation.

References:

McTaggart S (2005). Childhood Urinary Conditions. Australian Family Physician 34(11):937-941.

Quigley R (2008). Evaluation of hematuria and proteinuria: how should a paediatrician proceed? Current Opinion in Pediatrics. 20:140-144

Tu W and Shortliffe L (2010) evaluation of asymptomatic, atraumatic hematuria in adults and children. Nature Reviews Urology 7(4):189-194.

Print Friendly
1 Flares Twitter 0 Facebook 0 Google+ 0 LinkedIn 1 Email -- Filament.io 1 Flares ×

About 

Paediatric emergency physician interested in education, retrieval medicine and simulation. Lives in Brisbane where he enjoys falling off his mountain bike and being outsmarted by his pre-teen children.

@paedsem | + Ben Lawton | Ben's DFTB posts