47 XXY/46 XY Mosaic Klinefelter's Syndrome Presenting with Multiple Endocrine Abnormalities

We report here a rare case of 47 XXY/46 XY mosaic Klinefelter's syndrome associated with multiple endocrine disorders. A 35-year-old male admitted for the evaluation of renal dysfunction and recurrent bone fractures was diagnosed as having Klinefelter's syndrome by endocrinological examinations and sex chromosome analysis. He has suffered from diabetes mellitus for more than ten years. The serum FSH and LH levels were high together with low free testosterone and estradiol levels. There was a discrepancy between basal serum GH and somatomedin-C levels. On admission, thyroid function revealed thyrotoxicosis with low radioactive iodine uptake and negative thyroid autoantibodies. During hospitalization, serum FT3 and FT4 levels were gradually decreased and serum TSH levels became elevated, leading to the diagnosis of subacute thyroiditis. Serum ACTH levels showed high basal levels with delayed, exaggerated responses to insulin-induced hypoglycemia. Rapid ACTH test (1-24ACTH 0.25 mg) showed low cortisol responses and many of the adrenocortical steroids in plasma and urine were low or low normal. Furthermore, bone mineral density (BMD) by DEXA showed marked osteoporosis. Possible mechanisms underlying these varied endocrine disorders remain to be elucidated. (Internal Medicine 35: 396-402, 1996)