Clinical and pathological spectrums of aristolochic acid nephropathy

Aim: To study the clinical and pathological characteristics of aristolochic acid nephropathy (AAN). Methods: 86 patients with AAN during 2001 and 2009 in our department were recruited in this retrospective study. The clinical and pathological features were analyzed. Results: There were 47 males and 39 females, aging from 12 to 69 years old. Abnormal urine analysis and gastro-intestinal diseases were two main underlying causes for patients taking aristolochic acid (AA) containing drugs. All patients suffered from renal function impairment 19 patients (22.0%) presented with acute kidney injury (AKI), while 67 patients (78%) presented as chronic cases. Among them, 31 patients (36.0%) lacked symptoms, 30 patients (34.8%) were accompanied with hypertension, and 26 patients (30.2%) presented with gastrointestinal symptoms. Laboratory examination revealed elevated urine retinol-binding protein (RBP) (90.7%) and urine N-acetyl-beta-glucosaminidase (NAG) (80.2%). Anemia and glucosuria accounted for 64.0% and 58.1%, respectively. Renal biopsy showed prominent tubular brush border ablation (84.2%) in acute cases, while obvious tubular basement membrane (TBM) thickening (81.4%) and interstitial fibrosis were present in chronic cases. During the follow-up, 11(57.9%) acute cases gained renal function recovery. They had lower urine RBP level and lower incidence of hypokalemia than the non-recovery acute cases. In the chronic group, 27 patients (40.2%) progressed to end-stage renal disease (ESRD), with 11 dialysis and 5 renal transplantation cases. Conclusion: AAN patients usually suffered from renal impairment with an associated history of taking AA containing drugs. Proximal renal tubular dysfunction and structure destroying would be the main positive findings in laboratory tests and renal biopsy. Urine RBP and hypokalemia might determine the outcome of acute AAN patients.