Myopathy with ragged red fibres following renal transplantation: possible role of cyclosporin-induced hypomagnesaemia.

A 65-year-old man developed a painless proximal myopathy 7 years after commencing cyclosporin therapy following a successful cadaveric renal transplant. Muscle histology showed ragged red fibres and biochemical studies suggested mitochondrial dysfunction. The possible pathogenesis of this mitochondrial myopathy, particularly its relationship to cyclosporin-induced hypomagnesaemia, is discussed.