Measurement of urinary lactoferrin as a marker of urinary tract infection

The usefulness of the measurement of urinary lactoferrin (LF) released from polymorphonuclear leukocytes and of an immunochromatography test strip dev ised for measuring urinary LF for the simple and rapid diagnosis of urinary tract infections (UTI) was evaluated. Urine specimens were collected from apparently healthy persons and patients diagnosed as suffering from UTI, In the preliminary study, the LF concentrations in 121 normal specimens and 8 8 specimens from patients (60 with UTI) were quantified by an enzyme-linked immunosorbent assay, The LF concentration was 3,300.0 +/- 646.3 ng/ml (ave rage +/- standard error of the mean) in the specimens from UTI patients, wh ereas it was 30.4 +/- 2.7 ng/ml and 60.3 +/- 14.9 ng/ml in the specimens fr om healthy persons and the patients without UTI, respectively. Based on the se results, a 200-ng/ml LF concentration was chosen as the cutoff value for negativity. Each urine specimen was reexamined with the newly devised immu nochromatography (IC) test strip to calculate the indices of efficacy. Base d on the cutoff value, it was calculated that the sensitivity, specificity, and positive and negative predictive values of the IC test were 93.3, 89.3 , 86.2, and 94.9%, respectively, compared with the results of the microscop ic examination of the urine specimens for the presence of leukocytes. The r espective indices for UTI were calculated as 95.0, 92.9, 89.7, and 96.6%, T he tests were completed,within 10 min. These results indicated that urine L F measurement with the IC test strip provides a useful tool for the simple and rapid diagnosis of UTI.