title: Equine thyroid function assessment with the thyrotropin-releasing hormone response test.
abstract: The effect of thyrotropin-releasing hormone (TRH) on equine thyroid function was determined by quantifying serum thyroxine (T4) and 3,5,3'-triiodothyronine (T3) before and after TRH administration. Thyrotropin-releasing hormone was administered IV to adult horses (n = 5) and ponies (n = 6) at a dose of 1 mg or 0.5 mg, respectively. Serum T4 and T3 concentrations were determined before and 0.25, 0.5, 1, 2, 4, 6, 8, 12, and 24 hours after TRH administration. Serum T4 increased from a basal concentration of 24.4 +/- 8.7 ng/ml (mean +/- SD) to a maximum value of 48.2 +/- 10.2 by 4 hours after TRH administration. Serum T3 increased from a basal concentration of 0.44 +/- 0.18 ng/ml to a maximum value of 1.31 +/- 0.37 ng/ml by 2 hours after TRH administration. Seemingly, TRH increases serum concentrations of T4 and T3 and may be useful as a test of equine hypophysis-thyroid function.
authors.forename: C D
authors.initials: CD
authors.lastname: Lothrop
authors.forename: H L
authors.initials: HL
authors.lastname: Nolan
mesh_terms: D000375:Aging; D000818:Animals; D006736:Horses / Q000502:physiology*; D007700:Kinetics; D013961:Thyroid Gland / Q000254:growth & development / Q000502:physiology*; D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine / Q000097:blood*; D014284:Triiodothyronine / Q000097:blood*
chemical_list: D014284:Triiodothyronine; D013973:Thyrotropin-Releasing Hormone; D013974:Thyroxine