A case of myopathy and markedly elevated creatine kinase levels with hypocalcemia, hypomagnesemia, and hyposelenemia due to short bowel syndrome after rectal cancer resection.

A 66-year-old Japanese man was referred to our hospital with myalgia and muscle weakness. He had a history of rectal cancer, which invaded into the urinary bladder and ileum and was treated with chemotherapy, radiotherapy, resection of the rectum, colostomy, and ileal conduit construction. He showed recurrent markedly elevated serum creatine kinase levels and concurrent hypocalcemia. Muscle magnetic resonance imaging demonstrated abnormal signals in the proximal limb muscles, and needle electromyography showed myopathic changes. Further examination revealed hypomagnesemia and hyposelenemia with underlying short bowel syndrome. Calcium, magnesium and selenium supplementation improved his symptoms and laboratory findings.