Computer simulation for hormones related to primary thyropathy

Abstract

We propose a mathematical model of the human hypothalamus-anterior pituitary-thyroid system regulating basal metabolism, and practice computer simulation concerning primary thyropathy such as Graves' disease, hypothyroidism, T4-toxicosis and T3-toxicosis by use of this model. In order to throw light on properties of the system, indicial responses of the hormones, T4, T3, rT3, and TSH, and the function of the thyroid gland are computed. Medical treatments for Graves' disease and for hypothyroidism are simulated with a view to enhancing clinical significance. Performance of the simulation leads to an interesting result that when the convertion rate of blood T4 to blood T3 increases, explicit T3-toxicosis occurs, although the function of the thyroid gland is normal.

The Power‐Law Formalism as a Tool for Modeling Hormonal Systems

“…However, an accurate estimation of the parameter set corresponding to Equation 8 is difficult. Previous models of the same system can provide a clue for some of the parameters (see Hatakeyama and Yagi, 1985), but in many cases we found no clear experimental evidence for some of the included processes. In Appendix 2, we present the rationale behind the parameter set we use in our simulations (Table 11).…”

“…Furthermore, Merent metabolic states correlate with changes in such parameters, malung it difficult to define a representative set. Previous models have considered a classical compartmental analysis approach, and h e a r kinetics is assumed for many of the involved processes (Hatakeyama and Yagi, 1985). This assumption largely reduces the number of parameters to be determined.…”

“…For demonstrative purposes, we have selected a parameter set (Table 11) according to the following rationale: 1 THR: ui = F1/F2 (u:'" -u:" Degradation of TRH has been considered a firstorder process (Hatakeyama and Yagi, 1985), which involves hll = 1. Because ug refer to any of the external signals, the kinetic-order g18 can have different values in function of the specific signal.…”

“…h22 = 1 (Hatakeyama and Yagi, 1985). The release of TSH from the anterior pituitary is a complex process.…”

“…Previous models of thyroid metabolism have focused on the distribution of hormones in different body compartments through the analysis of injected radioactive tracers (see for instance Hays et al, 1988;Jacobs et al, 1997). Hatakeyama and Yagi (1985) proposed a model based on linear kinetics. T h~s model was able of reproducing key features of the system, including observations related to Graves' disease.…”