Influence of Thyroid Administration on Creatin Metabolism in Myxedema of Adults

Abstract

Little is known of the creatin metabolism of adult myxedema other than the absence of spontaneous creatinuria. In children with cretinism or hypothyroidism, the physiological creatinuria of childhood is absent. 1 , 2 When thyroid substance is given to such children, large amounts of creatin appear in the urine. 1 , 2 This effect has been interpreted as a restoration of the normal creatinuria of childhood. It is not known, however, how long the creatinuria persists with continued administration of thyroid substance in amounts sufficient to maintain a normal basal metabolism.

We have studied the creatin metabolism of 2 typical cases of spontaneous adult myxedema. Their diet was creatin-creatinin-free, and adequate in calories and protein. The ability to retain ingested creatin (1.32 gm.) was tested from time to time. After a control period, thyroid substance was administered in amounts sufficient to restore and maintain a normal basal metabolism. The usual improvement in signs and symptoms took place. Six cases of myxedema following total ablation of the thyroid∗ were studied in the same way, except that no thyroid substance was given. Our findings in spontaneous myxedema are given in Table I and Chart 1.

Results. In agreement with other workers, we found no creatinuria in spontaneous adult myxedema. Creatinuria was also absent in myxedema following total ablation of the thyroid. In both groups the retention of ingested creatin was normal. In spontaneous myxedema small doses of thyroid substance caused a pronounced creatinuria and a diminished tolerance to ingested creatin. This was observed before any elevation in the basal metabolism. In one case, at the height of the creatinuria, administration of glycine resulted in an excretion of extra creatin.