The natural history of immunoglobulin A nephropathy among patients with hematuria and minimal proteinuria

PURPOSE: To determine the natural history of immunoglobulin (Ig) A nephropa thy among patients who presented with hematuria and minimal proteinuria, an d factors associated with the development of adverse clinical events, such as proteinuria. SUBJECTS AND METHODS: In Hong Kong, all patients who present with isolated hematuria are referred for renal biopsy after urologic diseases are ruled o ut. We reviewed the clinical course of 72 consecutive patients with histolo gically confirmed IgA nephropathy who presented with hematuria and minimal proteinuria (0.4 g/day or less). All patients were normotensive and had nor mal renal function at presentation. Adverse events were defined as proteinu ria greater than 1 g per day, hypertension, or impaired renal function (ser um creatinine level 120 mu mol/L or estimated creatinine clearance <70 mt p er minute). RESULTS: The mean (<plus/minus> SD) age at presentation was 27 +/- 8 years; 56 (78%) were female. Nine patients (13%) had grade 2 histologic lesions. During a median follow-up of 7 years, 32 patients (44%) developed adverse e vents: 24 (33%) developed proteinuria of 1 g per day or more, 19 (26%) beca me hypertensive, and 5 (7%) developed impaired renal function. Another 30 p atients (42%) had persistently abnormal urinalysis examinations. Only 10 pa tients (14%) had complete resolution of hematuria. The median time for prog ression from proteinuria (>1 g/day) to renal impairment was 84 months (rang e 56 to 132). In a multivariate analysis, age at presentation (relative ris k [RR] per 10 years of age = 2.0; 95% confidence interval [Ci], 1.2 to 3.4) and histologic grade (grade 2 versus grade 1, RR = 4.5; 95% CI, 1.7 to 12) were independent predictors of developing an adverse event. CONCLUSIONS: IgA nephropathy that presents with hematuria and minimal prote inuria is usually a progressive disease. Life-long follow-up with regular m onitoring of blood pressure and proteinuria is recommended. Am (C) 2001 by Excerpta Medica, Inc.