False-positive results of the NMP22 test due to hematuria.

Purpose: The problem with available markers for bladder cancer is their low specificity and low positive predictive value due to false-positive results. False-positive results of the NMP22 nuclear matrix protein test (Matritech, Cambridge, Massachusetts) are usually observed in some clinical categories that are usually associated with hematuria and pyuria. This problem is especially serious in bladder cancer since 85% of patients present with hematuria.