Membranous glomerulonephritis induced by 2-mercaptopropionylglycine (2-MPG)

Thirty-two patients suffering from cystinuria were treated with 2-mercaptopropionylglycine (2-MPG) for 0.5-10 years (average 6.3 years). After 4-14 months of treatment at daily doses ranging from 500 to 2500 mg, three patients developed slight to moderate proteinuria. Two patients were subjected to renal biopsy which showed membranous glomerulonephritis. In one biopsy signs of progressive glomerular lesions were observed. In seven patients (22%) antinuclear antibodies were demonstrated. In one patient with biopsy-proven membranous glomerulonephritis, the antinuclear antibodies consisted of antihistone antibodies. The observations presented in this report indicate that 2-MPG, like D-penicillamine, could induce autoimmune reactions, in some cases leading to membranous glomerulonephritis. The prognosis seemed to be favorable. However, the occurrence of irreversible glomerular lesions as reported by us should be borne in mind when considering long-term treatment with 2-MPG. A continuous, close follow-up of patients on 2-MPG treatment is recommended.