Leucocyte esterase-nitrite screening method for pyuria and bacteriuria.

The value of the one minute leucocyte esterase-nitrite chemical strips as a screening procedure for detecting appreciable levels of pyuria and bacteriuria was assessed by comparison with microscopy and culture results. The likelihood that a negative leucocyte esterase result indicated less than 10 white cells/cu mm by microscopy (the negative predictive value), was 90.1% and that a negative nitrite result indicated less than 10(5) organisms/ml was 91.3%. There were many false positive results with both tests, however, and the overall predictive value of a positive leucocyte esterase or nitrite test, or both, was low. The leucocyte esterase-nitrite strip was neither sufficiently sensitive nor specific enough to be used as a cost effective method for screening urines in the laboratory.