ECENT monographs and a rapidly expanding literature1-4 indicate the interest and large amount of experimental work on the effects of hormones on lipid metabolism and atherosclerosis. The present paper reviews some of these data not with the purpose of dealing exhaustively with the available information but rather to provide the reader with a digestible summary.
The Thyroid GlandMyxedema is frequently cited as a condition demonstrating a relation between hormonally induced hypercholesteremia and atherosclerosis. Since this presumed relation has been one of the strongest pillars in the hypercholesteremia theory of atherogenesis, the evidence requires careful evaluation.A wealth of clinical and human experimental observation indicates a potent influence of the thyroid gland on the metabolism of cholesterol and other lipids. Blood cholesterol, serum phosphatides, and fatty acids are increased in myxedema.5' 6 In cretinous children, a high ratio of free to total serum cholesterol has been described.7 In adults with myxedema, however, normal or increased ester :total cholesterol ratio occurs. The rise in serum cholesterol is greater than that of phospholipid, and the cholesterol:phospholipid ratio is increased.8 An increase of lowdensity (beta) lipoproteins, both in spontaneous and in induced myxedema, is largely in the Sf 0-12 moiety but is found also in fractions Sf 12-400; all of the abnormalities are reversed by the administration of desiccated thyroid.9' 10 The lipoprotein abnormality