ABC of Kidney Disease

Urinary protein excretion of < 150 mg/day is normal (~30 mg of this is albumin and about 70–100 mg is Tamm-Horsfall (muco)protein, derived from the proximal renal tubule). Protein excretion can rise transiently with fever, acute illness, UTI and orthostatically. In pregnancy, the upper limit of normal protein excretion is around 300 mg/day. Persistent elevation of albumin excretion (microalbuminuria) and other proteins can indicate renal or systemic illness. Repeat positive dipstick tests for blood and protein in the urine two or three times to ensure the fi ndings are persistent. Microalbuminuria is an early sign of renal and cardiovascular dysfunction with adverse prognostic signifi cance. Microscopic haematuria is present in around 4% of the adult population – of whom at least 50% have glomerular disease. If initial GFR is normal, and proteinuria is absent, progressive loss of GFR amongst those people with microscopic haematuria of renal origin is rare, although long-term (and usually communitybased) follow-up is still recommended. Adults 50 years old or more should undergo cystoscopy if they have microscopic haematuria (MH). Any patient with MH who has abnormal renal function, proteinuria, hypertension and a normal cystoscopy, should be referred to a nephrologist.

Blood pressure control, reduction of proteinuria and cholesterol reduction are all useful therapeutic manoeuvres in those with renal causes of MH. All MH patients should have long-term follow-up of their renal function and blood pressure (this can, and often should be, community-based). Renal function is measured using creatinine, and this is now routinely converted into an estimated glomerular fi ltration rate (eGFR) value quickly and easily. The most common imaging technique now used for the kidney is the renal ultrasound, which can detect size, shape, symmetry of kidneys, and presence of tumour, stone or renal obstruction