ASSESSMENT OF THYROID FUNCTIONAL RESERVE IN THE CAT BY THE THYROTROPIN-STIMULATION TEST

  • 1 January 1983
    • journal article
    • research article
    • Vol. 44  (7) , 1229-1232
Abstract
Serum thyroxine (T4) concentrations before and after various i.v. doses of bovine TSH were measured over a 48-h period in 19 healthy cats. Base-line T4 values, as measured by radioimmunoassay, varied greatly. The peak T4 concentration occurred 6 h after TSH injection, and there was an increase in post-TSH serum T4 concentration that was linearly related to the logarithm of the dose. Greatest stimulation was seen with the highest dose used (1 U of TSH/kg of body wt), and 6 h after administration of this dose, the serum T4 concentration range was 4.1 to 8.4 .mu.g/dl. The post-TSH serum T4 concentration and the absolute increase in serum T4 concentration after TSH administration correlated more closely with the TSH dose than did the ratio of post-TSH serum T4 concentration to base-line T4 concentration. In cats with normal thyroid-binding protein concentrations, the former indices should represent the most reliable assessment of thyroid functional reserve.

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