Haematuria in Children
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Direct answer
Haematuria is defined as more than five red cells per high-power field on centrifuged urine, and it is classified as glomerular or non-glomerular by red cell shape and the presence of casts. Glomerular haematuria shows dysmorphic red cells, often with proteinuria and hypertension, whereas urinary infection, stones and trauma give isomorphic cells. A stepwise work-up excludes false positives and benign causes before nephrology referral.
What you must remember
- Glomerular features: dysmorphic red cells, red cell casts, proteinuria, oedema and hypertension, forming a nephritic picture.
- Non-glomerular features: isomorphic red cells, no casts and normal blood pressure; causes include urinary infection, stones, trauma and tumours.
- Pseudohaematuria: dipstick positive for blood with no red cells on microscopy suggests myoglobin or haemoglobin; beetroot and rifampicin discolour urine.
- Benign transient causes: exercise, menstruation and fever can cause haematuria that resolves; repeat testing is key.
- Thin basement membrane disease: a common cause of benign familial haematuria, with diffuse thinning of the basement membrane and normal kidney function.
- Imaging: renal and bladder ultrasound looks for stones and structural lesions.
- Biopsy triggers: haematuria with proteinuria, hypertension, reduced eGFR or low complement.
- Urinary calcium: a calcium-to-creatinine ratio helps identify hypercalciuria as a cause of microscopic haematuria.
A stepwise work-up for persistent haematuria
A 7-year-old boy has microscopic haematuria found on school screening, with normal blood pressure and no symptoms. The steps below decide whether he needs reassurance, further tests or referral.
- Confirm true haematuria. Repeat testing on fresh, centrifuged urine on two or three occasions.
- Exclude contamination and drugs. Check for menstruation, recent trauma, vigorous exercise, pigments and medicines.
- Check for infection. Urine culture; treat if positive and recheck once the course is complete.
- Measure protein, pressure and function. Protein-creatinine ratio, creatinine, eGFR, blood pressure and urinary calcium ratio.
- Examine the red cells. Phase-contrast microscopy: dysmorphic cells and casts suggest glomerular disease.
- Test specifically. Ultrasound for stones and structural disease, with complement, ASO and hearing and family history where indicated.
- Refer or observe. Nephrology referral for nephritic features, proteinuria or abnormal eGFR; surveillance for isolated benign cases.
Where the exam tries to catch you
Haematuria questions reward a systematic approach and attention to the red cells.
- Trap: dismissing a dipstick-positive result with no red cells on microscopy. Correct: this is pseudohaematuria from myoglobin or haemoglobin, so look for pigments and muscle injury.
- Trap: calling haematuria benign because kidney function is normal. Correct: proteinuria, hypertension and a family history of deafness or kidney disease still need assessment, as in Alport syndrome.
- Trap: assuming urinary infection explains every case. Correct: dysmorphic red cells with infection still need glomerular assessment.
- Trap: ordering a biopsy for isolated asymptomatic microscopic haematuria. Correct: biopsy is usually reserved for persistent proteinuria, hypertension or reduced eGFR.
Frequently asked questions
What is the threshold for significant haematuria on urine microscopy in children?
More than five red cells per high-power field on centrifuged urine is the usual threshold for significant haematuria in children. The sample should be repeated on separate occasions, because transient causes often produce a single positive result.
How do dysmorphic red cells indicate glomerular haematuria?
Dysmorphic red cells, seen on phase-contrast microscopy, indicate glomerular haematuria because the cells change shape as they pass through a damaged glomerular filter. Isomorphic red cells point instead to a lower urinary tract source such as infection, stones or trauma.
Which investigations are first-line when a child has persistent microscopic haematuria?
Urine microscopy, urine culture, protein-creatinine ratio, creatinine with eGFR, blood pressure and renal ultrasound are first-line when a child has persistent microscopic haematuria. Complement and further tests are added if glomerular disease is suspected.
Which benign familial condition causes isolated haematuria in children?
Thin basement membrane disease is the most common benign familial cause of isolated haematuria in children. It usually shows normal kidney function, but it can coexist with other causes, so the family history and proteinuria must still be checked.