The "point of no return" and the rate of progression in the natural history of IgA nephritis.

Background: Based on the observation of 7 patients with chronic IgA nephritis and on a course to end-stage renal failure after several years, D'Amico et al. [1993] reported on a "point of no return" at 2.5 to 3 mg/dl serum creatinine. After exceeding this limit all 7 patients exhibited an irreversible progressive renal failure.

Patients And Methods: Therefore, 115 patients with IgA nephritis from the "German Glomerulonephritis Therapy Study" were examined in order to look for the existence of such a "point of no return".

Results: Three different courses could be distinguished: a stable chronic course with constantly normal or only minor elevated serum creatinine lasting for years (91 patients), a progressive course with continuously increasing serum creatinine (22 patients), and a rare (only 2 patients) early acute course with a short-term increase of serum creatinine followed by a rapid return to the normal range. After exceeding 3 mg/dl serum creatinine no remissions were observed in the progressive cases. Sixteen patients showed a rapid, continuously progressive course until end-stage renal failure with exactly the same progression as the 7 patients of D'Amico et al. Six patients of the 22 progressors were not observed long enough. The serum creatinine level doubled on average from 3 to 6 mg/dl within 10 months.

Conclusion: Our study confirmed the existence of a "point of no return" at 3 mg/dl (265 micromol/l) during the natural course of chronic IgA nephritis.