Panciera D L, MacEwen E G, Atkins C E, Bosu W T, Refsal K R, Nachreiner R F
Department of Medical Sciences, School of Veterinary Medicine, University of Wisconsin-Madison 53706.
Am J Vet Res. 1990 Jan;51(1):22-6.
The effects of treatment with L-thyroxine (1 mg/m2 of body surface/d, PO, for 8 weeks) on the thyroxine (T4) and triiodothyronine (T3) responses to thyrotropin (TSH) and thyrotropin-releasing hormone (TRH) administration were determined in 10 euthyroid Beagles; 4 other dogs acted as controls. The TSH response test was performed before treatment and at weeks 2, 4, and 8 of treatment in all dogs and at 2 and 4 weeks after cessation of treatment in 6 dogs. The TRH response test was performed before treatment and at week 6 of treatment in all dogs and at 5 weeks after cessation of treatment in 6 dogs. Suppression of the T3 response to TSH was evident at treatment week 2, whereas the T4 response was suppressed at week 4 and remained suppressed for the duration of the study. Four weeks after stopping treatment, T4 and T3 responses to TSH in 2 dogs were within the hypothyroid range. The T4 response to TRH was completely suppressed after 6 weeks of thyroxine treatment, but returned to pretreatment values by 5 weeks after cessation of treatment. Suppression of thyroid and pituitary function is evident after administration of a replacement dose of L-thyroxine to euthyroid dogs.
在10只甲状腺功能正常的比格犬中，测定了左甲状腺素治疗（1mg/m²体表面积/天，口服，共8周）对甲状腺素（T4）和三碘甲状腺原氨酸（T3）对促甲状腺激素（TSH）及促甲状腺激素释放激素（TRH）给药反应的影响；另外4只犬作为对照。所有犬在治疗前、治疗第2、4和8周以及6只犬在停药后第2和4周进行TSH反应试验。所有犬在治疗前和治疗第6周以及6只犬在停药后第5周进行TRH反应试验。治疗第2周时，T3对TSH的反应明显受到抑制，而T4反应在第4周受到抑制，并在研究期间持续受到抑制。停药4周后，2只犬的T4和T3对TSH的反应处于甲状腺功能减退范围内。甲状腺素治疗6周后，T4对TRH的反应完全受到抑制，但在停药后5周恢复到治疗前水平。对甲状腺功能正常的犬给予替代剂量的左甲状腺素后，甲状腺和垂体功能受到明显抑制。
