The Predictors of Growth Hormone Secretion after L-dopa Stimulation Test in Adults

ABSTRACT

BACKGROUND: Twenty four-hour GH secretion reaches a peak in puberty and declines by 14% every decade in adult life. By age 60, most adults have a total 24-hour secretion rate indistinguishable from those of hypopituitary patients with organic lesions in pituitary gland. We performed this study to know about the predictors of GH secretion after L-dopa stimulation test in adults. METHODS: One hundred and ninety eight patients over the age of 45, who visited the menopausal clinic from Oct. 2001 to May 2002, were studied. We compared the peak GH value after the administration of L-dopa 500 mg by gender and age groups. Also, we compared the GH deficiency group to normal by anthropometric and measured variables. RESULTS: The mean of the stimulated GH peak value and the prevalence rate of growth hormone deficiency were greater in women than in men. GH-AUC after L-dopa stimulation correlated well with all measurements of adiposity. In GH deficiency group, the mean values of measured variables about adiposity were greater than normal in statistical significance. Logistic regression test revealed sex and abdominal obesity contributed significantly to predict GH deficiency after L-dopa stimulation test. The odds ratio of GH deficiency were 3.0 in women compared to men with 2.9 in abdominal obesity. CONCLUSION: Gender and adiposity were the predictors of GH deficiency in adults after L-dopa stimulation test rather than age and IGF-1 values.