The concept of human growth hormone precursor use is that if the body is supplied with the essential amino acids that make up an human growth hormone molecule, then the body may be more inclined to decide to use the additional supply of amino acids to produce human growth hormone more easily and frequently.
The effectiveness of human growth hormone precursor is limited primarily to young athletic individuals. The most frequent outcome with this approach is no change in human growth hormone level, but with no harm or undesirable hormonal changes. Very high doses may be required, necessitating a gentle approach in patients with decreased renal function, or who are on medications that require excretion by the kidney, especially aspirin related compounds. Response rates can be as low as 10%, with only a small actual rise in human growth hormone levels. Again, response rates and amounts fall with age, and IGF-1 levels should be checked before beginning and after 5-6 weeks, to verify any response. If there is no change, then this intervention should be abandoned.