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

Abstract

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. 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. 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. 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.