Hyperkalemia induced by indomethacin and naproxen and reversed by fludrocortisone.

We have described a patient with severe rheumatoid arthritis and a history of mefenamic acid nephropathy in whom hyperkalemia and inappropriate hypoaldosteronism were caused by both indomethacin and naproxen, without major decline in renal function. It is likely that preexisting renal disease predisposed this patient to type IV renal tubular acidosis with prostaglandin synthetase inhibitors. Because he was unable to discontinue nonsteroidal anti-inflammatory drug therapy, fludrocortisone was added, correcting the hyperkalemia and allowing indomethacin therapy to be continued safely.