Abstract

The interaction between various steroid hormones and parathyroid hormone was studied by observing the effect of each of these steroids on the parathyroid hormone dose-response curve in thyroparathyroidectomized rats. Methylprednisolone, estradiol or testosterone was given to rats for 48 hours prior to injection of parathyroid hormone. Increase in serum calcium six hours after parathyroid hormone was defined as the response. The steroids lowered the initial serum calcium taken prior to parathyroid hormone. Methylprednisolone inhibited the response at all dose levels of parathyroid hormone. Estradiol and testosterone enhanced the response to low doses of parathyroid hormone and inhibited the response to high doses.