Model Based Regulation of Thyroid Hormones in Patients with Hypothyroidism

A combined model predictive controller (MPC) and observer compensator is proposed to aid a physician in prescribing thyroid replacement therapy for patients with hypothyroidism. Hypothyroidism is a condition caused by underactive thyroid, where the thyroid gland is unable to produce a sufficient quantity of hormones. The thyroid malfunctioning could lead to other associated conditions like nausea, fatigue, heart conditions, high cholesterol, and elevated blood pressure. Thus, it is essential to ensure that the levels of thyroid hormones, Triiodothyronine
$(T_{3})$
and Thyroxine
$(T_{4})$
, are at healthy levels. The production of these hormones is governed by the hypothalamus-pituitary-thyroid (HPT) axis, a part of the endocrine system. Hypothyroidism cannot be cured but can be regulated through medication. The standard practice to control hypothyroidism is to prescribe a constant daily dosage of synthetic
$T_{4}$
(Levothyroxine) and, in some cases, an additional dose of synthetic
$T_{3}$
(Liothyronine). In this paper, a combined MPC-observer compensator is proposed that generates the amount of medication doses that the patient should receive. The compensator's prescription can then be used by physicians to prescribe constant daily doses of the synthetic hormone replacements.