Long-term evolution of patients with isolated C3 mesangial glomerulonephritis.

Isolated mesangial C3 proliferative glomerulonephritis is a nephropathy poorly defined among glomerular diseases. Clinical picture is characterized by episodes of gross hematuria and/or persistent or recurrent microhematuria and/or proteinuria. Short-term prognosis (less than 3 years) is considered to be benign, although not much information is available in reference to long-term follow-up. We reviewed all renal biopsies performed in our center between 1978 and 1992 (n = 2,200) in order to study clinical course of these patients. Isolated mesangial C3 deposition was found in 11 cases (0.5%). Isolated proteinuria (> 0.5 g/d) was present in 3 patients and nephrotic syndrome in 2. Hematuria with proteinuria was detected in 5 patients. In one patient hematuria was the only clinical finding. Arterial hypertension was observed in 4 cases. At the time of renal biopsy, renal function was accurately normal in all but one patient. In our series, renal function showed no changes during the first 3 years, accordingly to data referred to in the literature. After 7 years of follow-up, however, renal function was declining in 4 of 5 patients who developed terminal renal failure up to requiring hemodialysis. Therefore, initial benign prognosis ascribed to this glomerulonephritis would not be confirmed in a long-term follow-up.