The frequent occurrence of hematuria in children necessitates diagnostic evaluation. Hematuria may occur with either renal or lower urinary tract disease. Clarification of the etiology of hematuria, whether microscopic or gross, is facilited by
localizing the site of bleeding to the kidney (glomerular) or the lower urinary tract (non-glomerular). The mean cellular volume (MCV) of urinary red blood cells (RBCs) of pediatric patients with glomerular (group I; n=77) and non-glomerular
(group
II;
n=34) hematuria was determined using Coulter Counter Model S plus IV. We found that re blood cells of glomerular origin had a smaller volume than non-glomerular cells(73.79 9.75 m3 vs 83.55 3.77 m3, p<0.001). If an urinary MCV equal to 80.56 m3
was
taken as the cut-off value between glomerular and non-glomerular hematuria, a correct assessment of the site of bleeding was made in 89 (80%) of the 111 patients studied (sensitivity 76%, specificity 88%).
The ratio of the urinary erythrocyte MCV to that in blood(Umcv/Bmcv) was compared with the diagnosis. If an Umcv/Bmcv ratio equal to 0.95 was taken as the cut-off value between glomerular and non-glomerular hematuria, a correct assessment of the
site of
bleeding was made in 93 (83%) of the 111 patients studied (sensitivity 79.6%, specificity 94%).
Coulter counter analysis of urine provides a simple noninvasive and objective aid to the diagnosis of hematurai. This test, when used early in the management of pediatric patients with hematuria, may help to avoid invasive investigations.
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