Severe respiratory muscle weakness related to long-term colchicine therapy.

We report a case of colchicine-induced myopathy, in which the initial presenting and predominant clinical feature was respiratory muscle dysfunction; there was also chronic renal failure and electromyographically-measured myopathy. Discontinuation of colchicine led to marked improvement. Colchicine discontinuation was the only therapy performed (other medications were unchanged), and within 3 weeks the patient had regained motor function and resumed daily activities. Myopathy from primary biliary cirrhosis was ruled out. In contrast to acute colchicine intoxication, chronic colchicine toxicity is related to prolonged use rather than colchicine serum level, so colchicine serum level was not measured and did not affect the decision to discontinue colchicine. Although the diagnosis was not confirmed by muscle biopsy, we believe the typical presentation and the rapid improvement after withdrawing colchicine confirm the diagnosis. We conclude that long-term colchicine therapy, especially in the setting of chronic renal failure, can produce symptomatic respiratory muscle weakness.