THE SOURCE OF EXCESS CREATINE FOLLOWING METHYL TESTOSTERONE1

Abstract

When methyl testosterone was administered orally to normal [male][male] or [female][female] on a low creatine diet, the rise in plasma levels of creatine was low during the 1st ten days, but increased rapidly during the 2d 10 days, exceeding the renal threshold and producing creatinuria. If creatine was ingested, or if plasma creatine levels were high due to renal disease, the marked rise in plasma levels occurred sooner after beginning ingestipn of the steroid. This is interpreted as indicating there is a limited capacity for storage of creatine in the tissues, which can be filled by creatine from any source. Increased creati-nemia and creatinuria followed admn. of methyl testosterone to patients with severe hepatic disease. The effect of methyl testosterone on creatine formation was observed in nephrosis and mild nephritis, but was abolished in severe nephritis. It would seem that the kidney is the primary site of action, or that it supplies an essential precursor to some other tissue.