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OBJECTIVE: Febrile urinary tract infection (UTI) is a common problem among children. The diagnosis and management of acute pyelonephritis is a challenge, particularly during infancy. The distinction between acute pyelonephritis and UTI without renal involvement is very important, because renal infection may cause parenchymal scarring and thus requires more aggressive investigation and follow-up monitoring. However, this distinction is not easy among children, because common clinical findings and laboratory parameters are nonspecific, especially among young children. In an attempt to differentiate acute pyelonephritis from febrile UTI without renal lesions in a group of 100 children, we measured serum levels of procalcitonin (PCT), a new marker of infection. The objective of the study was to determine the accuracy of PCT measurements, compared with C-reactive protein (CRP) measurements, in diagnosing acute renal involvement during febrile UTI and in predicting subsequent scars, as assessed with 99mTc-dimercaptosuccinic acid (DMSA) scintigraphy. DESIGN: Serum CRP levels, erythrocyte sedimentation rates, leukocyte counts, and PCT levels were measured for 100 children, 1 month to 13 years of age, admitted for suspected febrile UTI (first episode). Renal parenchymal involvement was evaluated with DMSA scintigraphy within 5 days after admission. The DMSA study was repeated 6 months later if the initial results were abnormal. RESULTS: The mean PCT level was significantly higher in acute pyelonephritis than in UTI without renal lesions (4.48 +/- 5.84 ng/mL vs 0.44 +/- 0.30 ng/mL). In these 2 groups, the mean CRP levels were 106 +/- 68.8 mg/L and 36.4 +/- 26 mg/L, mean erythrocyte sedimentation rates were 79.1 +/- 33 mm/hour and 58.5 +/- 33 mm/hour, and leukocyte counts were 18 492 +/- 6839 cells/mm3 and 16 741 +/- 5302 cells/mm3, respectively. For the prediction of acute pyelonephritis, the sensitivity and specificity of PCT measurements were 83.3% and 93.6%, respectively; CRP measurements had a sensitivity of 94.4% but a specificity of only 31.9%. Positive and negative predictive values for prediction of renal involvement with PCT measurements were 93.7% and 83% and those with CRP measurements were 61.4% and 83.3%, respectively. When inflammatory markers were correlated with the severity of the renal lesions, as assessed with DMSA scintigraphy, a highly significant correlation with both PCT and CRP levels was found. However, when the 2 parameters were correlated with renal scarring in follow-up scans, a significant positive association was found only for PCT levels. CONCLUSIONS: Serum PCT levels may be a sensitive and specific measure for early diagnosis of acute pyelonephritis and determination of the severity of renal parenchymal involvement. Therefore, this measurement could be useful for the treatment of children with febrile UTIs, allowing prediction of patients at risk of permanent parenchymal renal lesions. [ABSTRACT FROM AUTHOR]

Objective: The aim of this study was to define the association between age and the occurrence of acute pyelonephritis and renal scars., Methods: Between 1999 and 2002, all children 0 to 14 years of age consecutively seen with a first febrile urinary tract infection were enrolled in the study. (99m)Tc-Dimercaptosuccinic acid renal scintigraphy was performed within 5 days after admission for the detection of renal parenchymal involvement. The presence of vesicoureteral reflux was assessed by using cystography performed 1 month after the infection. If the acute scan results were abnormal, then follow-up (99m)Tc-dimercaptosuccinic acid scanning was performed after 6 months, to assess the frequency of scars., Results: A total of 316 children were enrolled in the study (190 children <1 year, 99 children 1-4 years, and 27 children 5-14 years of age). (99m)Tc-Dimercaptosuccinic acid scintigraphy revealed that 59% of the children had renal involvement in the acute phase of infection. The frequency of kidney involvement in infants <1 year of age (49%) was significantly lower than that in children 1 to 4 years of age (73%) and >5 years of age (81%). Of the 187 children with positive acute (99m)Tc-dimercaptosuccinic acid scan results, 123 underwent repeat scintigraphy after 6 months. Renal scars were found for 28% of children <1 year, 37% of children 1 to 4 years, and 53% of children 5 to 14 years of age. No significant differences in the frequency of scars and the presence or absence of vesicoureteral reflux were noted., Conclusions: Our findings confirm that acute pyelonephritis and subsequent renal scarring occur only in some children with first febrile urinary tract infections. Children <1 year of age with febrile urinary tract infections have a lower risk of parenchymal localization of infection and renal scarring.