Do urine dipsticks reliably predict microhematuria? The bloody truth!

Some literature has cast doubt on the reliability of urine dipsticks in the search for microhematuria. In our study, 2,000 urine dipsticks (two brands) were tested on urine samples containing 0, 0 to 5, 5 to 10, 10 to 20, and 20 to 50 red blood cells per high-power field. The same samples were retested four hours later and the same sticks were tested after four months of aging. Variables controlled for included observer, lighting, performance according to package insert, pH, specific gravity, white blood cells, ascorbic acid, protein, age of dipstick, and exposure of urine to povidine or cleaning solutions. Results obtained using both N-Multistix and Chemstrip 9 urine dipsticks correlated closely with the degree of hematuria. Overall sensitivity was 100%, and specificity was 99.3%. We conclude that these urine dipsticks are reliable and are not affected when tested on urine four hours after void, and that Chemstrips 9 are much more reliable than are N-Multistix if aged in air for four months.