Value of the urine strip test in the early diagnosis of bacterial peritonitis

BACKGROUND: In an effort to detect the presence of leukocytes in the peritoneal dialysate fluid (PDF) a urine dipstick may be practical for the early detection of peritonitis in peritoneal dialysis patients. METHODS: The study was performed in 44 samples of four children with peritonitis. The total counts of white blood cell (WBC) and polimorphonuclear neutrophils (PMNs) were found using both a hemocytometer (CELDYN 3700 R) and a microscopic method. The existence of leukocytes was investigated by urine dipstick tests. RESULTS: The dipstick test was correlated with both hemocytometer and microscopic methods (r = 0.537, P = 0.001; r = 0.560, P = 0.0001, respectively). Our results revealed no false negative values in all strip categories. At the proposed cut-off point (> 100/mm3 of WBC count), a 3+ reading on the strip test reached a sensitivity of 100% for the detection of peritonitis with a specificity of 100%. A 2+ reading reached a sensitivity of 100% with lower specificity (71.4%) at the same cut-off point. The dipstick test correlated significantly with the total counts of PMNs (r = 0.80, P = 0.0001). All positive strip categories had more than 50% of PMNs with a low PMN percentage of negative strip category in PDF samples. CONCLUSION: It is proposed that the strip test might be a valuable test to diagnose bacterial peritonitis through the detection of both WBC and PMN in peritoneal dialysis patients.