Does pyridium (phenazopyridine) prevent a urine dipstick for leukocytes from showing ? can a woman with flank pain and urinary burning on pyridium (phenazopyridine) have a pyelonephriti

Yes and yes: Pyridium (phenazopyridine) dyes the urine orange & that color can interfere with the dipstick test for leukocytes. But the gold-standards for diagnosing UTI's is looking for leukocytes under the microscope (for immediate dx) & culture.Pyridium (phenazopyridine) does not interfere with those. Pyridium (phenazopyridine) only reduces symptoms & doesn't treat the infection. You might have pyelonephritis, which can be serious. Seek medical attention ASAP!