A sampling protocol for the thyrotropin-stimulation test in the horse

Abstract

Summary A study was designed to assess the secretory response of thyroid glands in horses to an economically feasible dose (5 IU) of thyrotropin injected iv , and to establish valid blood sampling periods in cases in which thyroxine concentrations were different from base-line values. Significant ( P <0.001) response (doubling or near-doubling of base line) occurred as early as 3 hours after thyrotropin administration, with peak response at 4 to 5 hours. It was concluded that administration of 5 IU of thyrotropin is economical and effective in the horse, with collection of a second blood sample possible as early as 3 hours after administration.