In the article: “Principles of Endocrine Regulation: Reconciling Tensions Between Robustness in Performance and Adaptation to Change.” (Ref.1) the authors describe how their mathematical model can describe perfect homeostasis. The patterns of TRH, TSH, FT3 and FT4 are plotted. The FT3 value is preserved whatever changes in the other hormones.
In the next two plots, the K32* is changed to 0.3 and 3. Changes in the patterns between the three hormones TSH, FT4 and TRH.
Redefinition of FT3 reference ranges?
The FT4 production rate parameter k32 is the proportionality constant,
positive feedforward of TSH onto FT4 (downstream, activating (short red arrow)).
FT4 increases as k32 increases and TRH-TSH decreases (due to the negative feedback k134 and k234 (green and blue bars)
- Hoermann R, Pekker MJ, Midgley JEM, Larisch R and Dietrich JW (2022) Principles of Endocrine Regulation: Reconciling Tensions Between Robustness in Performance and Adaptation to Change. Front. Endocrinol. 13:825107. doi: 10.3389/fendo.2022.825107 https://www.frontiersin.org/articles/10.3389/fendo.2022.825107/full