L-DOPA INDUCED GROWTH HORMONE SECRETION. COMPARISON WITH INSULIN TOLERANCE TEST, ARGININE INFUSION AND SLEEP INDUCED GH-SECRETION

Abstract

ABSTRACT Plasma growth hormone (GH) levels following oral stimulation with 500 mg of L-dopa were determined and compared with those following arginine infusion, insulin tolerance test (ITT) and sleep induced secretion. Peak values following L-dopa were 13.3 ± 2.5 ng/ml and not different from those following arginine (16.4 ± 3. 3ng/ml) and those during nocturnal sleep (14.7 ± 1.2 ng/ml), but significantly less than GH peaks during ITT (24.9 ± 3.4 ng/ml). The rate of false negative results to L-dopa was 15% and seems to be higher than following other stimuli. – In contrast to the stimulatory effect in healthy subjects L-dopa had a suppressive effect on the GH levels in 4 patients with acromegaly.