ABNORMAL RESPONSE OF GROWTH-HORMONE TO OR AL GLUCOSE-TOLERANCE TEST IN OBESITY

In obesity, it is well known that basal growth hormone (GH) levels can be suppressed and they may show an impaired response to varieus stimu li like hypoglycemia, stress, and GHRH. However, the inhibitory effect of hyperglycemia on GH in this condition has not been well studied. W e analyzed the GH response to art oral glucose tolerance test (OGTT) i n 25 unselected patients with morbid obesity who were not diabetic, gl ucose-intolerant or affected by renal or hepatic disease. Ten (40 %) o f the 25 subjects had an abnormal response of GH to the OGTT, expresse d by a lack of suppression of GH levels below 2 mu g/L within 60 minut es of glucose administration. Three subjects even had a paradoxal incr ease of GH levels of more than 50 % of the basal level. There was no s ignificant difference between these subjects regarding their-age, BMI and, serum levels of glucose, insulin, C peptide, or insulin/glucose r atio. After weight loss, three of four patients normalized their GH re sponse. Thus, we conclude that patients with morbid obesity frequently have abnormal response of GH to OGTT (40 % vs 4-8 % in normal subject s). This finding must be taken into consideration when interpreting GH levels in these patients. A normalization of this response call be ex pected after weight loss.