BIOLOGIC ACTIVITY OF PORK AND BEEF THYROID PREPARATIONS*

Abstract

A relatively precise and simplified antigoitrogenic assay method and supporting calorigenic tests in rats have consistently shown a significant difference (P 0.01) in the relative potency of pork versus beef thyroid preparations. Regardless of geographic origin, or method of preparation, 5 beef materials assayed 40-63% of pork thyro-globulin reference standards on the basis of either total or "thyroxine" iodine. Only 1 of 10 pork preparations was significantly less potent than standard at P=0.01. On the basis of these data beef thyroid preparations diluted to conform with U.S.P. or B.P. specifications for thyroid would be approximately half as potent as pork preparations similarly diluted. This study demonstrates the need for quantitative biochemical characterization of the glands of these and other species.