Combined use of urinary alpha1-microglobulin and 99mTc DMSA scintigraphy in the diagnosis and follow-up of acute pyelonephritis and cystitis in children.

Abstract

In the absence of specific symptomatology in children and neurogenic bladder disease patients, the early diagnosis of acute pyelonephritis is a challenge. The aim of the present study was to determine if dimercaptosuccinic acid (DMSA) lesion-positive (acute pyelonephritis) patients have elevated urinary alpha1-microglobulin (alpha1-MG) excretion (no false negatives) and if DMSA lesion-negative (cystitis) patients have normal urinary alpha1-MG excretion (no false positives). A selected population of 62 children above 3 months of age with a proven urinary tract infection were administered a DMSA scan. A control scan was performed after the acute phase of the illness, and the diagnosis of pyelonephritis (n = 44) was made retrospectively. The urinary alpha1-MG was determined by immunonephelometry. The urinary alpha1-MG-creatinine ratio was highly sensitive (98%) and specific (100%) and correlated with the DMSA scintigraphy images. Only 1 of the 44 patients with pyelonephritis and all of the cystitis patients (n = 18) had a normal urinary alpha1-MG (<10 mg/g). The drop in absolute DMSA uptake correlated significantly (r = 0. 758, p < 0.001) with the urinary alpha1-MG-creatinine ratio. The urinary alpha1-MG-creatinine ratio was significantly higher (p < 0. 02) in bilateral than in unilateral pyelonephritis. DMSA lesion-positive (acute pyelonephritis) patients have elevated urinary alpha1-MG excretion and DMSA lesion-negative (cystitis) patients have normal urinary alpha1-MG excretion.