Procalcitonin is a marker of severity of renal lesions in pyelonephritis

Objective, In an attempt to differentiate acute pyelonephritis from lower u rinary tract infection (UTI), we measured serum procalcitonin levels, a rec ently described marker of infection. We compared it with other commonly use d inflammatory markers and evaluated its ability to predict renal involveme nt as assessed by dimercaptosuccinic acid (DMSA) scintigraphy. Methods. Serum C-reactive protein, leukocyte counts, and procalcitonin leve ls were measured in 80 children, 1 month to 16 years of age, admitted for s uspected pyelonephritis. Renal involvement was assessed by Te-99m-DMSA scin tigraphy in the first 5 days after admission. The examination was repeated at least 3 months later if the first result was abnormal. Results. In lower UTI, the mean procalcitonin (PCT) was 0.38 mu g/L +/- 0.1 9 compared with 5.37 mu g/L +/- 1.9 in pyelonephritis. In these two groups, respectively, leukocyte counts were 10939/mm(3) +/- 834 and 17429/mm(3) +/ - 994, and C-reactive protein (CRP) levels were 30.3 mg/L +/- 7.6 and 120.8 mg/L +/- 8.9. When inflammatory markers were correlated to the severity of the renal lesion as ranked by DMSA scintigraphy, we found a highly signifi cant correlation with plasma levels of PCT, but borderline significance wit h CRP and none with leukocyte counts. Patients without vesicoureteral reflu x. had a mean PCT of 5.16 mu g/L +/- 2.33, which was not significantly diff erent from that in patients with reflux who had a mean PCT of 5.76 mu g/L /- 3.49. For the prediction of renal lesions at admission, CRP had a sensit ivity of 100% and a specificity of 26.1%. The sensitivity and specificity o f PCT were 70.3% and 82.6%, respectively. Conclusion, We conclude that serum PCT levels were increased significantly in children with febrile UTI when renal parenchymal involvement (assessed b y DMSA scintigraphy) was present and allowed for prediction of patients at risk of severe renal lesions.