No, arginine isn't the drug given for replacement. The drug (amino acid) is used to stimulate GH in the GH stimulation test. The growth hormone that is now given is "somatropin [rDNA origin], which is a polypeptide hormone of recombinant DNA origin. It has 191 amino acid residues and a molecular weight of 22,124 daltons. The amino acid sequence of the product is identical to that of human growth hormone of pituitary origin (somatropin)." They used to use ground up pituitaries from deceased individuals, but they stopped this practice some time ago, due to the emergence of an old disease in a new way, Jakob-Creutzfeld virus, which causes dementia. Maybe you didn't want to know that... but that is history...lol. Minnie | 