Factors associated with microhematuria in asymptomatic young men.

The prevalence of asymptomatic microhematuria (two to four or more erythrocytes per high-power field) in 1341 male Air Force personnel was 5.4%. The most powerful predictor of microhematuria (nearly 15-fold increased prevalence) was a history of recurrent microhematuria during the previous five years. Recurrent microscopic hematuria was present in 14.5% (8/55) of men with a history of urethritis, accounting for 26% (8/31) of the cases of recurrent microscopic hematuria. The prevalence of microhematuria was not affected by physical exercise, flight duty, or sexual intercourse during the 24 h preceding the urinalysis.