Little research......I'm 52 so 2 IU's is noticeable to me.
Arvat E, Ceda G, Ramunni J, Lanfranco F, Aimaretti G, Gianotti L, Broglio F, Ghigo E. The IGF-I response to very low rHGH doses is preserved in human ageing. Clin Endocrinol (Oxf) 1998 Dec;49(6):757-63. Department of Internal Medicine, University of Turin. Sensitivity of body tissues to HGH is preserved, and perhaps even increased with age, despite the reduction of internal pituitary secretion. When given 1 unit of rHGH by injection daily for 4 days: In a young group, average age 29, with a baseline average IGF-1 of 230, it increased to 301 after the series of 1-unit HGH injections. In an elderly group, average age 69, with average baseline IGF-1 of 123, IGF-1 increased to 208 after a series of daily 1-unit injections. [A consistent finding in recent published studies is that IGF-1 increases by approximately 80 ng/ml for each one unit injected daily, and that levels achieving 200 or higher results in better clinical benefit.]