Nature of the Disturbed Calcium Metabolism in Thyrotoxicosis and Myxœdema

Abstract

VARIOUS theories have been put forward to explain the excessive calcium output in thyrotoxicosis including an increased metabolism per se¹, neutralization of acid products², direct stimulating catabolic action of thyroxin on bone, and a co-existing hyper-parathyroidism³. For reasons to be given later, all these theories are unsatisfactory. As a result of direct experiments and observations⁴ on normal subjects and cases of thyrotoxicosis, myxœdema and parathyroid tetany, a new theory has been formulated. It is believed that in thyrotoxicosis, an excessive secretion of thyroxin acts directly on the kidneys, stimulating them to increase their output of calcium. This may be achieved either as a result of the increased metabolism per se or by lowering the renal threshold for calcium.