The app was developed and well-validated from real normal and hypothyroid human data and it features a simple and intuitive user interface, designed to promote understanding of the basic physiology of this complex endocrine system – by laypersons as well as by clinicians and clinical educators and researchers.


THYROSIM is particularly useful for understanding and safely exploring effects of perturbing the real system, in various ways – without the need for any real human or animal experimentation. The DIRECTIONS and EXAMPLE explain and illustrate normal physiological conditions. Users can then conduct simulated ‘‘what-if’’ experiments, to challenge the simulation model with abnormal conditions – as explained on the app interface pages.


For example, users can simulate hypothyroidism (when the thyroid hormone level in blood is too low) or thyroid hormone malabsorption from the gut. Patients with hypothyroidism can visualize the effects of thyroid hormone replacement therapy, promoting adherence to their doctor’s dosing prescriptions, and also understand better why they should take thyroid hormone replacement drugs without food – facilitating understanding of impaired absorption of the drug in the presence of food. Thyroid cancer patients (any layperson) can visualize the effects of partial or complete surgical removal of the thyroid gland (thyroidectomy) on blood hormone levels, and thereby understand why they need individualized hormone replacement therapy, and so on.

Physicians and laypersons can use THYROSIM as a patient education tool. Scientists can use THYROSIM for clinical research purposes. Clinical and pharmacology educators can use THYROSIM to teach medical and pharmacology students basic thyroid hormone physiology and pathophysiology, complete with easy to understand graphical renditions of the results of “what-if” experimentation with the simulator. Trainees and other students can benefit from use of THYROSIM as a means to deepen and test their understanding the complexities of the “pituitary-thyroid axis”, the primary organ interactions regulating blood thyroid hormone levels by feedback control.
The THYROSIM model has been the basis for several important clinical study applications for well over a decade, with details published in the medical journals Thyroid and Frontiers in Endocrinology.

Disclaimer: This tool is for simulation and visualization and does not establish a standard of care. Treatment decisions must be made based on the independent judgment of health care providers and each patient’s individual circumstances. This tool is not intended to take the place of physician judgment in diagnosing and treatment of particular patients.

The American Thyroid Association® considers use of this resource to be voluntary.

Please see the following publication reference for information on the background and process behind the mobile app:
Predicting Optimal Combination LT4 + LT3 Therapy for Hypothyroidism Based on Residual Thyroid Function
https://www.frontiersin.org/articles/10.3389/fendo.2019.00746/full