Urinary macrophage migration inhibitory factor in children with urinary tract infection

Macrophage migration inhibitory factor (MIF) plays an essential pathophysiological role in inflammatory reactions. The aim of this study was to investigate the clinical utility of urine MIF (uMIF) level in predicting urinary tract infections (UTI). This multicenter, prospective study was conducted over a 1-year period between March 2008 and March 2009. Sixty patients with symptomatic culture-proven UTI and 29 healthy children were recruited. Urine MIF was measured by enzyme-linked immunosorbent assay. The mean MIF level was found to be significantly higher in the UTI group than in the control group (1082.82 vs. 211.45 pg/ml, p = 0.0001). Receiver operating characteristic (ROC) analysis revealed that the optimal cut-off uMIF level was 295 pg/ml for uMIF to predict UTI. The sensitivity and specificity of this cut-off level were 91.7% and 69%, respectively. Mean uMIF/creatinine (Cr) was also significantly higher in the UTI group than in the control group (2400.69 vs. 267.56 pg/mgCr, p = 0.0001). At a cut-off of 815 pg/mgCr for uMIF/Cr, the sensitivity and specificity were 95 and 79%, respectively. The area under curve (AUC) was 0.848 (standard error 0.040, 95% confidence interval 0.756–0.915) for uMIF and 0.889 (0.034, 0.805–0.946) for uMIF/Cr. Urine MIF/Cr was significantly higher in the patients with a positive leukocyte esterase reaction in the urine (p = 0.047), leukocytosis (p = 0.0001) and positive C-reactive protein level in serum (p = 0.003). The uMIF level was not related to leukocytosis, positive CRP level in serum and leukocyte esterase reaction in the urine. Neither uMIF nor uMIF/Cr were correlated to the positive urine nitrite test, pyuria, urine pH and specific gravity (p > 0.05). These results suggest that urine MIF and uMIF/Cr can be used for the early prediction of UTI in children.