Abstract
In expts. during which creatine and guanidoacetic acid were ingested by a normal subject, no evidence was obtained suggesting that methylation of guanidoacetic acid to form creatine is retarded when an excess of creatine is present. It was possible to produce a substantial creatinuria by the admn. of guanidoacetic acid alone, thus simulating the effect of methyltestosterone on creatine metabolism. This suggests that the sole action of methyltestosterone on creatine metabolism is in acceleration of guanidoacetic acid synthesis.