Prediction of Renal Cortical Involvement Using Serum and Urinary Inflammatory Markers in Children with Febrile Urinary Tract Infection

Background Erythrocyte sedimentation rate (ESR), serum C-reactive protein (CRP), urinary β2 microglobulin, antibody-coated bacteria in the urine sediment, and urinary lactic dehydrogenase (LDH) are more traditional tests used to diagnose true pyelonephritis. Acute-phase dimercaptosuccinic acid (DMSA) scan is a sensitive method for diagnosis of true pyelonephritis. Objectives Defining predictive values of traditional inflammatory serologic parameters, urine analysis indexes, kidney ultrasonography and fever in children with febrile urinary tract infection for predicting renal cortical involvement. Patients and Methods In a prospective study, 20 children admitted due to febrile urinary tract infection were assessed for renal cortical involvement by Technetium-99 m-labeled dimercapto succinic acid (TC99-DMSA) scan. Body temperature ≥ 39C, white blood cell count ≥ 15000 cell/µL, positive C-reactive protein, erythrocyte sedimentation rate (first hour) ≥ 30 mm/h, presence of proteinuria, severe pyuria or bacteriuria on urine analysis, urine specific gravity ≤ 1010, and renal ultrasonography were used for predicting renal cortical involvement. Sensitivity, specificity, positive and negative predictive values of these variables were measured by specific formula. Results The highest measured sensitivity was 100% (erythrocyte sedimentation rate ≥ 30 mm/h). Urine specific gravity < 1010 and bacteriuria had the highest (75%) and lowest (20%) specificities respectively. The highest and lowest positive predictive values were 85.7% ( urine specific gravity < 1010) and 57% (proteinuria), whereas the highest and lowest negative predictive values were related to erythrocyte sedimentation rate > 30 mm/h (100%) and proteinuria (11%) respectively. Normal sonography had a low sensitivity for predicting absence of renal involvement (23%). Conclusions Erythrocyte sedimentation rate ≥ 30 mm/h is a sensitive marker with high negative predictive value for predicting renal involvement in febrile urinary tract infection.