I would like to know how hypothyroid the model can get when the different parameters from fig. 6. A in Principles, Hoermann et al 2022.
Recap text from fig. 6. A: FT4 levels (blue curve) decline, but the mechanisms in system (sys. 10) protect FT3 levels (green curve), keeping them in a range close to the original level, as the percentage of the estimate of FT4 production rate constant (k32 = 0.4 to 1.1) decreases – as typical at the onset of hypothyroidism in patients suffering from autoimmune thyroiditis and progressive thyroid destruction. Other parameters are chosen within ranges, k423 = 0.2-0.3, k43 = 0.7-0.8 and k42 = 0.1-0.2, to approximate the relative contributions to FT3 production according to (32).
![](https://www.glensbo.dk/circle/wp-content/uploads/2022/10/k32_0.4_k423_03.png)
The figures shows the most hypothyroid state the model can achieve under the given conditions.
![](https://www.glensbo.dk/circle/wp-content/uploads/2022/10/k32_04_k42_0.2.png)
Trying to change the k42 parameter which results in a slight decrease of TSH
![](https://www.glensbo.dk/circle/wp-content/uploads/2022/10/k32_04_drug4_08-1-1024x519.png)
Adding drug4 = 0.8 to the most hypothyroid state. We see FT3 is not returning to the level in the perfect homeostasis. See sys1 below. Apart from that FT3 drops with lower k32.
![](https://www.glensbo.dk/circle/wp-content/uploads/2022/10/sys1_no-drugs.png)
![](https://www.glensbo.dk/circle/wp-content/uploads/2022/10/sys1_drug4_08.png)
Here I have tried to show the pattern following perfect homeostasis plus drug4. Mimicing the situation where a patient gets unnecessary LT-4 treatment. Will it be possible to identify the pattern and use it to get the patient off LT-4? Is the pattern disguised by the transformation to real hormone values?