Rapid Detection of Pyuria by Leukocyte Esterase Activity

To evaluate whether leukocyte esterase activity is a useful biochemical marker of pyuria, we examined urine from 20 healthy volunteers, 47 patients with renal disease, and 399 specimens from 72 hospitalized patients with catheters. Microscopic quantification of leukocytes (centrifuged sediment and volumetric chamber count) was compared with esterase activity in the urine. The three tests were closely correlated. The coefficients were esterase vs chamber,.85; esterase vs sediment,.74; and chamber vs sediment,.82. The chamber count and esterase test were more sensitive than the sediment in detecting pyuria. Using ten or more cells per cubic millimeter as denoting significant pyuria, the esterase test gave a sensitivity of 87.9% and a specificity of 94.3%. Esterase activity did not require intact cells and was not affected by urinary pH, protein, bacteriuria, underlying disease, renal function, or receipt of a variety of drugs. (JAMA1981;245:1653-1655)