Membranous nephropathy due to chronic mercury poisoning from traditional Indian medicines: report of five cases

Mercury contained in traditional medicines can cause chronic poisoning, which can cause membranous nephropathy (MN). We report five cases of nephrotic syndrome caused by MN with evidence of chronic mercury poisoning due to consumption of traditional Indian medicines such as Siddha and Ayurveda, which to our knowledge are the first such reports. All patients were seronegative for antibodies against phospholipase A2 receptor (PLA2R). Two patients, who had severe nephrotic syndrome, had received Siddha medicine for prolonged period and oral chelation with dimercaptopropane-1-sulfonic acid was successful in eliminating mercury, resulting in an improvement in nephrotic state in these patients. We suggest that mercury poisoning should be entertained in patients with anti-PLA2R antibody-negative MN, with history of consumption of traditional Indian medicines.