[A case of insulin receptor abnormality (type A)]

A sixteen year old woman came to the hospital for glucosuria and amenorrhea. Physical examination demonstrated that she had hirsutism, deepening of voice, and pigmented skin in her axillary lesion which was histologically diagnosed as acanthosis nigricans. Ultrasonography showed polycystic ovaries. A diabetic pattern of 75 g oral glucose tolerance test, very high levels of serum insulin (fasting: 320, peak: 1,220 microU/ml), and hyperandrogenism characterized by increases of urine 17-KS, serum testosterone and DHEA-S were found. Both serum insulin and insulin-receptor antibodies were found to be negative. Insulin binding to both erythrocytes and cultured skin fibroblasts were significantly decreased (about 30% of normal controls). Scatchard plot analysis demonstrated decreased number of insulin receptors to about 30% of the normal controls. We therefore diagnosed that she had insulin receptor abnormality, Type A in Kahn's classification.