Tuyển tập các báo cáo nghiên cứu khoa học quốc tế về bệnh thú y đề tài: Circadian variations of serum thyroxine, free thyroxine and 3, 5, 3'triiodothyronine concentrations in healthy dogs | J. Vet. Set. 2006 7 1 25-29 JOURNAL OF Veterinary Science Circadian variations of serum thyroxine free thyroxine and 3 5 3 triiodothyronine concentrations in healthy dogs Woo-Pil Hoh Tae-Ho Oh Department of Veterinary Internal Medicine College of Veterinary Medicine Kyungpook National University Daegu 702-701 Korea This study was to determine the daily fluctuation of serum thyroxine tT4 free thyroxine fr4 3 5 3 -triiodo-thyronine Tj concentrations in healthy dogs. Thyroid function of these dogs was evaluated on the basis of results of TSH response test. Samples for the measurement of serum tT4 fr4 and Tj concentrations were obtained at 3hour intervals from 8 00 to 20 00. Serum tT4 fr4 and Tj concentrations were measured by the enzyme chemiluminescent immunoassay ECLIA . Mean Tj concentrations had no significant differences according to the sample collection time during the day. Mean tT4 and fr4 concentrations at 11 00 were pg dl and ng dl respectively and mean tT4 and fr4 at 14 00 were pg dl and ng dl respectively. These concentrations were significantly high compared with tT4 and fr4 concentrations at 8 00 which were pg dl and ng dl respectively p . According to the sample collection time mean tT4 and fr4 concentrations changed with similar fluctuation during the day. Based on these results it was considered that measurement of serum tT4 and fr4 concentrations from 11 00 to 14 00 might more easily diagnose the canine hypothyroidism in practice. Key words dog fluctuation free thyroxine thyroxine 3 5 3 -triiodothyronine Introduction Thyroid hormones are iodine-containing amino acids synthesized and secreted in the thyroid gland by changes in the circulating concentration of pituitary thyrotropin. All circulating thyroxine T4 and 20 of 3 5 3 -triiodothyr-onine T3 are derived from the thyroid gland 7 8 11 . In the blood more than 99 of T4 and T3 is bound to plasma Corresponding author Tel 82-53-950-5959
