In a study of 342 kids with asymptomatic microscopic haematuria, no cause was found in the large majority of patients. The most common cause discovered was hypercalciuria (16% of patients) followed by post–streptococcal glomerulonephritis (1%). No evidence for value of early detection of hypercalciuria (may be at long-term risk for nephrolithiasis and bone demineralization). The children with asymptomatic post–streptococcal glomerulonephritis all improved spontaneously and without complication. None had evidence of urinary tract infection! Clinically insignificant abnormalities in the upper urinary tracts of 5 children and grade 3 reflux in 1 [Arch Pediatr Adolesc Med. 2005;159(4):353-355. doi:10.1001/archpedi.159.4.353]
Asympt recurrent can be monitored for 5yr!
- frank blood,
- other features (joints, rash, wt loss)
Haematuria defined as persistent dipstick positive on at least 3 occasions for at least 3 months. Else as >2rbc per HPF (not same as flow cytometry). Then consider:
- Red cells or not?
- myoglobinuria = haemolysis
- Porphyrins, other unusual pigments
- Proteinuria or not?
If spot urine abnormal, repeat on early morning urine and then proceed to 12-14hr collection. Urine calcium/creatinine has age specific normals, high at birth (up to 1.5 in toddlers) falling to adult max of 0.7 at age 7. High levels especially significant in the presence of a normal plasma calcium
Investigations – only do bloods if macroscopic or nephritis suspected:
- Do urine culture and microscopy.
- Do PCR if proteinuria.
- If macroscopic, do FBC, U&Es, LFTs, Coag.
- Renal USS
- Screen family members with urinalysis
- Spot urine calcium/creatinine
- If acute nephritis, do C3/4, ASOT, immunoglobulins, ANCA, anti GBM as below.
- If stones suspected, do 2 sets of spot urine Ca/creat, Oxalate/creat, Urate, amino & organic acids, pH, KUB.
- Tumour – bladder (colour changes during voiding, dysuria with sterile culture) or kidney
- IgA nephropathy – persistent, progressive in 30%, diagnosis on biopsy
- Alports – usually X dominant, deafness in minority, cataracts in 10%
- Sickle cell – 1% macroscopic, 16% microscopic. Papillary necrosis, usually painless, episodic. May progress to sickle nephropathy.
- Venous thrombosis – esp neonates, nephrotics.
- Vascular – AVM, Nutcracker syndrome (compression of the left renal vein between the abdominal aorta and SMA)
- Nail-patella syndrome (BM disorder, like Alports)
- Polycystic Kidney Disease
Biopsy if persistent high grade microscopic, or microscopic with proteinuria (>150 mg/24 hr)/hypertension/impaired renal function, or 2 episodes of gross haematuria. Cystoscopy for bladder problem.