Thyroid homeostasis as studied by computer simulation

Physico-chemical factors alone may account for much of the thyroid gland homeostasis and by inference for homeostasis of basal energy metabolism in mammals. Computer simulations indicate that changes of several of the important rate constants for thyroid function have little effect on circulating thyroid hormone concentrations. This was especially true of the rate constants for thyroid hormone release from the thyroid gland and to a lesser extent of the rate constants governing thyroid hormone metabolism and excretion. The rate at which thyroid hormone levels in blood respond to changes was rather slow indicating that transient changes in dietary iodine or in the rate constants governing thyroid function would have little effect. If changes taking place over several days, such as during the initiation of lactation, the parameters of thyroid function change at a corresponding rate.