A METHOD FOR THE BIOLOGICAL ASSAY OF PHOSPHATURIC ACTIVITY IN PARATHYROID EXTRACTS1

Publisher Website
Google Scholar
Abstract
A biological assay method has been developed for estimation of the phosphaturic activity of parathyroid extracts. It is based on the increased urinary excretion of inorganic phosphate by 2-month old male rats during the first 6 hours after parathyroidectomy. The extract to be tested is injected immediately after parathyroidectomy and just before beginning the collection of urine. Various factors of importance in the assay method were studied, including the use of parathyroidectomized rather than intact rats, the optimal time and the completeness of the urine collection, a stock diet rather than a low-calcium diet, and the dose-response curve. The most favorable conditions yielded a reasonably rapid and sensitive assay method with a mean index of precision ([lambda]) of 0.30. Several applications of the method are described, in particular the estimation of the ratio of phosphaturic to calcium-mobilizing activity in parathyroid extracts.