Role of Procalcitonin in Evaluation of Urinary Tract Infection in children

ABSTRACT
Background: Febrile UTI is a common problem among children. The distinction between acute pyelonephritis and lower UTI is very important, because renal infection may cause parenchymal scarring and thus requires more aggressive investigations and follow-up monitoring. The clinical findings and laboratory markers such as leukocyte count and CRP do not reliably distinguish acute pyelonephritis from lower UTI and asses renal scaring is by using dimercaptosuccinic acid (DMSA) scan, which is very expensive, not available in all centers and exposes the patients to radiation. Objectives: To determine the procalcitonin (PCT) level in children with UTI to evaluate it as a marker for early diagnosis and differentiation between upper and lower UTI. Methods: This study was carried on 30 patients with UTI, 8 males and 22 females with mean age 7.7 ± 2.5 years. They were divided into 2 groups: 12 patients with upper UTI and 18 patients with lower UTI. Complete urine analysis, urine culture and sensitivity, CBC, CRP, renal function tests and PCT level were done for all patients. CRP, PCT and urine culture and sensitivity were repeated again after treatment. Ten healthy children matched for age and sex served as controls. Results: The mean PCT level was significantly higher in patients with UTI than controls (1.67 ± 0.9 ng/ml vs 0.37 ± 0.2 ng/ml, p < 0.001). Also PCT level was significantly higher in cases of acute pyelonephritis than lower UTI (2.38 ± 1.02 ng/ml, p <0.01). After treatment PCT decreased significantly, but was still significantly higher in acute pyelonephritis than lower UTI (1.02 ± 0.38 ng/ml vs 0.59 ± 0.23 ng/ml, p <0.01). The sensitivity and specificity for PCT were 86.67%  & 90% respectively with positive and negative predictive values of 96.29% & 69.92% respectively. For CRP, the sensitivity and specificity were 66.67% & 70% respectively, with positive and negative predictive values of 86.96% & 41.18% respectively. After treatment still 6 patients with acute pyelonephritis had significantly higher levels of PCT (1.2 ± 0.67 ng/ml vs 0.37 ± 0.2 ng/ml, p < 0.01) than the control which means renal parenchymal affection. Conclusions: Serum PCT levels may be a sensitivity and specificity measure for early diagnosis of acute UTI and differentiation between upper and lower UTI. Also PCT can help in determination of the severity of renal parenchymal involvement and scaring. So we recommend imaging studied as DMSA if serum PCT level is still high after 2 weeks of proper treatment.