The effect of thyroid on calcium metabolism.

Patients with exophthalmic goiter and normal controls were given a carefully weighed diet deficient in calcium (0.1 gm. per day) but adequate in total calories. On this regime a negative calcium balance was established in all subjects. Determinations were made of total calcium, nitrogen and phosphorus in urine and feces. Frequent basal metabolic rates and determinations of calcium and phosphorus of blood were also made.

Three typical, rather severe cases of exophthalmic goiter showed a very high calcium excretion—one of them five times the average found in a series of controls. Phosphorus excretion was also increased though not as markedly as calcium. This high excretion was maintained with a high basal metabolic rate, but as the basal metabolic rate fell (following the ingestion of Lugol's solution and operation), the calcium excretion also fell markedly and approached normal.

One myxedema patient showed a calcium excretion below normal. Two of the normal controls also took thyroid and thyroxin in amounts sufficient to raise metabolism twenty per cent. On this diet, inadequate in calcium, the calcium excretion rose definitely with the metabolic rate.

In all of these subjects the blood calcium and phosphorus was normal.

The significance of these findings and their possible relation to parathyroid activity is being further investigated on cases of myxedema, adenoma of the thyroid, parathyroid tetany, and on animals.