Accession Number : AD0716588

Title :   Computer Simulation of the Kinetics of Binding Distribution and Metabolism of Thyroxine and Triiodothyronine in Man,

Corporate Author : CALIFORNIA UNIV LOS ANGELES SCHOOL OF ENGINEERING AND APPLIED SCIENCE

Personal Author(s) : DiStefano,Joseph J. , III ; Chang,Ronald F.

Report Date : 01 AUG 1970

Pagination or Media Count : 47

Abstract : A nonlinear compartmental-type model has been formulated to represent the dynamics of binding of T3 and T4 to albumin, TBG and TBPA in plasma; the distribution of the thyroid hormones into four slowly equilibrating and rapidly equilibrating extravascular pools; and the metabolism or disposal of T3 and T4. The postulated in vivo conversion of T4 to T3 has also been included. The model equations and constraints have been simulated on a digital computer and some of the parameters of the model have been estimated from the data in the literature. The thirteen unknown parameters have been identified by fitting the dynamic responses of model-simulations to new data on the disappearance of simultaneously injected tracer doses of T3 and T4 in euthyroid man. Several predictive experiments performed on the model-simulation include: the effects of nonzero T4-T3 conversion on tracer responses; the T3 response to a 0.5 micrograms T4 tracer injection; thyroidectomy of the model with zero and up to 50 percent T4-T3 conversion; and the transient responses to thyroidectomy followed by a 250 micrograms intravenous T4 injection at twelve hours. The results of these experiments suggest that simulation of up to 50 percent T4-T3 conversion has a quantitatively insignificant effect on the model kinetics and total T3 concentration tends to acutely decrease more or less sharply in response to 250 micrograms or 0.5 micrograms T4 intravenous injections. (Author)

Descriptors :   (*THYROID HORMONES, MODELS(SIMULATIONS)), (*METABOLISM, THYROID HORMONES), (*THYROXINE, METABOLISM), DISTRIBUTION, HORMONES, COMPUTERS, MATHEMATICAL MODELS, THYROID GLAND, SURGERY, TABLES(DATA), PROTEINS, ALBUMINS, TRACER STUDIES, HUMANS

Subject Categories : Biochemistry
      Anatomy and Physiology

Distribution Statement : APPROVED FOR PUBLIC RELEASE