Methods Patients. The study comprised 38 women and 9 men, aged 17 to 68 years, with a median age of 33 years from the Department of Nephrology, Lund. All patients had or had had a history of symptomatic UT! consisting of attacks of acute pyelonephritis. The diagnosis of UTI was based on the presence of significant bacteriuria, that is, iObacteria/mI. For the diagnosis of acute pyelonephritis, the additional criteria were used: fever> 38.5 C, back or loin pains, and erythrocyte sedimentation rate> 25 mm/hr. To be included in the UTI-free groups, it was required that there should be negative urine cultures for the 6 months previous to the study.

Blood serum samples were obtained as part of regular controls and were analyzed for creatinine and autoantibodies to THP. The sera from 9 patients with acute pyelonephritis were obtained 6 to 22 days (median, 13 days) after onset of the symptoms. Sera samples were stored at—20 C until analyzed. All patients were radiologically examined with intravenous urography (IVU) and micturation urethrocystography. Renal damage was defined as scarring, calyceal blunting, and/or abnormally small kidney (s). The findings on micturation urethrocystography were graded as follows:(1) no refiux or reflux into the ureter but not to the pelvis,(2) reflux into the renal pelvis, and (3) previous rellux into the renal pelvis in patients who had undergone a successful antireflux operation. The patients were divided into four groups according to the serum creatinine concentrations, roentgenologic findings, and presence of UT! at the time of testing. The results are summarized in Table I.