Isolated asymptomatic microhematuria: a cross-sectional analysis of test-positive and test-negative patients.

The relationship of asymptomatic microhematuria to urologic disease in a general population was studied by using population-based data resources in Rochester, Minnesota, to identify 635 patients with isolated asymptomatic microhematuria (AMs) and 635 controls. Prevalences of minor urologic diseases were 41.8% in those with positive tests (AMs) and 36.9% in controls (p greater than 0.05). Moderately serious urologic diseases were found in 16.7% of AMs and 9.2% of controls (p = 0.006); significant differences were found only for renal calculi and various causes of increased serum creatinine. Urologic cancers were found in 1.2% of AMs and 0.2% of controls (p = 0.04), but only prostatic carcinoma was found in a significantly higher percentage of those with positive tests (p = 0.047). Urologic cancers were found in 3.6% of test-positive patients with greater than 8 RBC/high-power field vs. 0.5% of those with 1-8 RBC/high-power field and 0.2% of controls (p greater than 0.05). The predictive value of low-grade isolated asymptomatic microhematuria is too low to be of value in screening for urologic cancers in unselected patients, and only certain moderately serious urologic diseases and prostatic cancer were more frequent in patients who had asymptomatic microhematuria than in controls.