The renal allograft donor with isolated microhematuria.

Recently, there has been extensive debate about extending the criteria for accepting living donors to include the presence of mild renal abnormalities such as isolated microhematuria. Hematuria defined as the detection of greater than five red blood cells per high power field can be associated with abnormalities throughout the urinary tract. Detection of casts or dysmorphic red blood cells in the urine sediment with or without proteinuria could indicate underlying intrinsic renal disease. Anatomic causes, such as stones and tumors, should be excluded; cystoscopy may be indicated to exclude bladder pathology. Obviously, urinary tract infection, uncontrolled hypertension and latent diabetes mellitus must be excluded. Microscopic hematuria could be associated with mesangial IgA deposits; as 10% of first-degree relatives of patients with IgA glomerulonephritis suffer from microhematuria and/or proteinuria that may require consideration of renal biopsy. Microhematuria could also be associated with other known hereditary renal diseases such as C3 deposits disease, IgM nephropathy, autosomal dominant polycystic kidney disease, Alport's syndrome or thin basement membrane disease. In conclusion, careful assessment of isolated microhematuria, in the context of living kidney donation, is mandatory as results may reveal occult renal disease that may contraindicate kidney donation.