The project deals with mathematical models of the thyroid control loop, their simulation, validation and comparison with each other. With regard to diseases, it is limited to models for hypothyroidism with the aim of reducing the time it takes to determine medication. The number of diseases of the thyroid and the hormonal system has been increasing in recent years. The project is being carried out in the course of a cooperation between the TUW and MUW, with data from a retrospective study carried out at the endocrinology department of Vienna General Hospital being used to validate and evaluate the validity of the mathematical models.

Through its influence on the hypothalamus and pituitary gland, the thyroid gland plays an important role in the regulation of the operative hormone system. Intensive studies of the mutual influence of the thyroid, pituitary and hypothalamus show an individual balance of the hormones secreted. This individual balance means that adjusting the correct dose of medication for the treatment of various thyroid disorders takes several appointments with specialists over a long period of time. In pregnancy, this process is further complicated by the body's production of the hormone hCG, which stimulates the thyroid gland to produce additional hormones. The use of mathematical models is intended to support the handling of this medical issue in order to be able to design the therapy more effectively.

The project is being carried out in close cooperation with the endocrinology outpatient clinic of Vienna General Hospital, which collects data in the course of a retrospective study on thyroid diseases and makes it available to this project for the validation process of the mathematical models.

The long-term goal is to provide a mathematical model that provides information about the individual hormone balance of patients on the basis of previous measurement data in order to shorten the time it takes to determine the required dosage. The design of such a model is based on two different, fundamental approaches.

On the basis of a timeless model, which for hormonal balance only includes the development of the values of the hormone TSH, released by the pituitary gland, and the thyroid hormone FT4, more information about the individual balance is to be gained by validating this model with patient data. The timeless model has already been validated with a small data set; through the existing cooperation with the endocrinology outpatient clinic of the Vienna General Hospital and the resulting access to more data from people suffering from hypothyroidism, the quality and significance of the model can be evaluated in more detail.

The measurement data, recorded at appointments over a longer period of time, offer the possibility to extend the knowledge about the development of hormonal balance to time-dependent models. By validating time-dependent models and evaluating the results in comparison to the aforementioned timeless models, the time dependence of the development of hormone values can be taken into account from the time of diagnosis, or the indication of hypothyroidism, including the medication administered. A time-dependent model also offers the possibility to analyse the development of the hormone hCG and its influence on the thyroid regulatory circuit, as this concentration is dependent on the week of pregnancy. The following figure shows a schematic representation of the components of the mathematical model and their mutual influence.