Experimental Basis for Anabolic Therapy

Currently, chemical analogs of the naturally occurring hormones are being prepared and studied in large quantities in the hope of finding useful therapeutic agents. The recent demonstration that naturally occurring hormones that were once thought to be single are really complexes of metabolically active substances has multiplied the number of known hormones remarkably. For example, in the case of the thyroid hormones we now know that thyroxin is but one of a large complex of chemically related substances and that some of its metabolites are, in fact, more potent than thyroxin itself. There is also some indication that the degradation products may be different, not only quantitatively but also qualitatively, in their metabolic actions. For example, triiodothyropropionic acid, which may be looked upon as a deiodinated, deaminated analogue of thyroxin, has only 15% of the ability of l-thyroxin to increase oxygen consumption and only one-quarter of its ability to