Identification of the source of haematuria by automated measurement of mean corpuscular volume of urinary red cells

The appearance of red blood cells in the urine may be the result of disease of any segment of the urinary tract. To determine whether there might be a distinguishing characteristic of the urinary red cells which appear during glomerular disease but is absent in other urinary tract diseases, the mean corpuscular volumes (MCV) of urinary and blood erythrocytes were measured by a Coulter counter in 34 children with haematuria. Diagnosis of the underlying renal or urinary tract disease was made by clinical and laboratory findings, including radiological investigations, renal biopsy and cystoscopy. The ratio of the urinary erythrocyte MCV to that in blood (Umcv/Bmcv) was compared with the diagnosis. The Umcv/Bmcv ratio was less than 1.0 in all children with glomerular disease and was greater than 1.0 in all but 1 of the patients with non-glomerular disease. This study suggests that the Umcv/Bmcv ratio provides a simple and useful technique for distinguishing between glomerular and non-glomerular haematuria. Such determination would help in guiding appropriate diagnostic evaluation.