Identification of the source of haematuria by automated measurement of red cell volume.

The mean corpuscular volume (MCV) of urinary erythrocytes was measured by a Coulter Counter in 42 patients with asymptomatic haematuria. All patients had the source of haematuria established by a renal biopsy, cystoscopy or radiology. The mean urine MCV was significantly less in those with glomerular disease (n = 21) than in those with non-glomerular haematuria (n = 21). In every patient with glomerulonephritis, urinary erythrocytes were smaller than those in their own venous blood. Conversely, urinary red cells larger than venous blood were confined to patients with a non-glomerular source. Coulter analysis of urine provides a simple and objective aid to the diagnosis of haematuria.