Abstract
Thyrotoxic crisis in a 42-year-old woman with mitochondrial diabetes mellitus is reported. She was diagnosed with juvenile diabetes mellitus during the first pregnancy at the age of 24, and has since been treated with insulin therapy. Her mother also had diabetes mellitus. The patient noticed a swelling in her anterior neck in November 1996. She visited our hospital due to slight fever, frequent vomiting and body weight loss on May 1, 1997. She had short stature, hearing loss, tachycardia, and somnolence without exophthalmos or tremor. Serum thyroid hormone levels were markedly increased, where as serum thyroid stimulating hormone (TSH) was suppressed. Antimicrosomal antibody and TSH binding inhibitory immunoglobulin were strongly positive. Thecefore, thyrotoxic crisis was diagnosed, and dexamethasone and propranolol were administered. Serum Cpeptide was undetectable, but antibodies for glutamic acid decarboxylase and islet-cell antibody were both negative. Mitochondrial DNA analysis revealed a point mutation of A 3243 G. The present case suggests that thyrotoxic crisis could develop even though mitochondrial function is suppressed due to mitochondrial gene mutation.
