The effect of age on the prevalence of asymptomatic microscopic hematuria

The medical files of a sample of men who had been followed by annual examinations from 1968 through 1978 were selected, using a random number sequence from the records of the Israel Air Force. One group of 430 men, ages 21-23 at entry, and a second group of 264 men, ages 25-28 at entry, were studied. The results of the urinalysis at entry and after ten years of follow-up were recorded. The point prevalence of all degrees of microhematuria increased significantly with age in both groups. One to three or more red blood cells (RBCs) per high-power field (HPF) were found in 3.5% of the subjects ages 21-23 at entry and in 14.2% in the same subjects ten years later (P = 0.001). Similarly, one to three or more RBCs per HPF were found in 4.9% of men ages 25-28 at entry and in 11.7% of the same subjects ten years later (P = 0.001). The authors conclude that age needs to be taken into consideration in drawing the line between physiologic and pathologic microhematuria.