Arginine-Initiated Release of Human Growth Hormone

To improve the usefulness of testing pituitary function by the response of human growth hormone (HGH) to I.V. arginine loads, arginine infusions were given under a variety of conditions to healthy subjects aged 17 to 35. The minimum effective arginine load causing release of HGH was 1/6 gm per pound of body weight in men and 1/12 gm per pound of body weight in women. At each of three dosage schedules used, women responded with greater increases in plasma HGH than men. Treatment of men with diethylstilbestrol augmented their HGH response to arginine, whereas methyltestosterone pretreatment did not decrease the response in women. The HGH response to arginine was not abolished by acute hyperglycemia but was attenuated or delayed by a previous stimulus for HGH release. In the use of this test of pituitary function, it is necessary to use a proper dose of arginine, to avoid other stimuli of HGH release, and to pretreat men with estrogens.