Phosphatase Activity of the Bones and Kidneys in Thyrotoxicosis. ∗

Abstract

Considerable experimental work has been done within the past few years on the phosphatase activity of various bodily tissues. Robison 1 showed that soluble salts of hexosemonophosphoric esters were hydrolyzed by an enzyme present in ossifying cartilage, kidney, and the shafts of long bones. Kay, 2 Robison, 1 and others have shown that the intestinal mucosa, kidney, and whole bone contain the greatest concentration of this enzyme. Furthermore, the plasma and tissue phosphatase activity has been shown to vary from the normal in certain pathological conditions. Page 3 has shown that bone phosphatase is diminished if an excess of vitamin D is fed to an animal, along with the coincident decalcification of bone and metastatic calcification of other tissues. Parathormone has also been shown 4 to depress the activity of the bone enzyme in rats, though not to the same extent as the administration of vitamin D.

It is known that the thyroid gland also profoundly influences calcium and phosphorus metabolism. In exophthalmic goiter the excretion of calcium and phosphorus is markedly increased and there is decalcification of bone though the level of calcium and phosphorus in the blood remains normal. 5 Kay 6 and Hunter 7 have demonstrated an increase in the phosphatase activity of the plasma in hyperthyroidism but a correlation of the increased excretion of calcium and phosphorus and the decalcification of bone with the phosphatase activity of the kidneys and bones, respectively, has not been attempted. The present study was undertaken to determine whether such a correlation exists by measuring the phosphatase content of the bones and kidneys of animals rendered thyrotoxic by injections of thyroxin.