Characterization of early IgA nephropathy

Histological grading of 45 patients with clinical early immunoglobulin A (I gA) nephropathy was correlated with disease progression over a median follo w-up of 123 months. Clinical early IgA nephropathy was defined as a serum c reatinine level of 1.3 mg/dL or less, proteinuria of 0.4 g/d or less of pro tein, and the absence of hypertension at the time of renal biopsy, Disease progression was related to the occurrence of impaired renal function, incre ased proteinuria, and hypertension. We applied a previously described chron icity-based histological grading to the renal biopsy specimen and also asse ssed acute glomerular lesions. Disease progression was observed in 44.4% of these patients. Forty patients (89%) showed glomerular grade 1 (GG1) and 5 patients (11%) showed GG2, but this grading did not correlate with disease progression. However, when GG1 was subdivided into GG1a (mean sclerosis pe r glomerulus <10%) and GG1b (mean sclerosis per glomerulus 1(10% to <25%), GG1a correlated with nonprogressive disease. Tubulointerstitial grade also correlated with disease progression but was associated with a low sensitivi ty for predicting nonprogressive disease. Hyaline arteriolosclerosis and ac ute glomerular lesions did not correlate with disease progression. The chro nicity-based histological grading is not only applicable to clinical early IgA nephropathy, but also more importantly, it characterizes GG1a in a subs et of patients with a very low risk for disease progression, which can be r egarded as genuine early IgA nephropathy, (C) 2000 by the National Kidney F oundation, Inc.