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Thyrotropic feedback control

Synonyms: Pituitary-thyroid feedback control, pituitary-thyroid axis, thyrotropic axis, Astwood-Hoskins loop German: Thyreotroper Regelkreis

1 Definition

Thyrotropic feedback control is a feedback control system that connects pituitary and thyroid gland. It regulates the concentration of thyroid hormones in blood plasma.

Source: Dietrich, J. W. (2002). Pituitary-thyroid feedback control. Development and clinical application of a non-linear model. Berlin, Logos-Verlag.

2 Physiology

The pituitary gland secretes the glandotropic hormone thyrotropin (TSH) that stimulates secretion of thyroxine (T4) and triiodothyronine (T3) in the thyroid gland. Conversely, thyroid hormones inhibit secretion of TSH in the form of degenerative feedback so that the system achieves equilibrium levels of the involved hormones. Furthermore, TSH-incretion depends from the level of the releasing hormone TRH that is formed in the hypothalamus. TRH thus acts in a way similar to a setpoint of the feedback control.

This main feedback interaction is complemented by additional "plugged in" feedback loops, e.g. an ultra-short-feedback control where TSH inhibits its own secretion, a long-feedback loop connecting thyroid hormones with TRH secretion and feedback loops for plasma protein binding of T4 and T3.

3 Functional states of pituitary-thyroid feedback control

4 Diagnosis

The feedback control's function can be assessed in most cases by determining the following hormones:

In special cases the following parameters are required:

5 References

  1. Salter, WT (1940). The Endocrine Function of Iodine. Harvard University Press, Cambridge.
  2. Hoskins, RG (1949). The thyroid-pituitary apparatus as a servo (feed-back) mechanism. J. clin. Endocr. Metab. 9, 1429-1431.
  3. Astwood EB. Mechanism of action of antithyroid compounds. Brookhaven Symp Biol. 1955 Feb;7:61-72; discussion, 72-3. PubMed PMID 14351812
  4. Panda JN, Turner CW. Thyroxine feed-back on the regulation of thyrotropin [TSH secretion]. J Physiol. 1968 Mar;195(1):29-37. PMID 5644487; PMCID: PMC1557901
  5. Prummel MF, Brokken LJ, Meduri G, Misrahi M, Bakker O, Wiersinga WM.: Expression of the thyroid-stimulating hormone receptor in the folliculo-stellate cells of the human anterior pituitary. J Clin Endocrinol Metab. 2000 Nov;85(11):4347-53. PMID: 11095478
  6. Brokken LJ, Scheenhart JW, Wiersinga WM, Prummel MF.: Suppression of serum TSH by Graves' Ig: evidence for a functional pituitary TSH receptor. J Clin Endocrinol Metab. 2001 Oct;86(10):4814-7. PMID: 11600546
  7. Brokken LJ, Wiersinga WM, Prummel MF.: Thyrotropin receptor autoantibodies are associated with continued thyrotropin suppression in treated euthyroid Graves' disease patients. J Clin Endocrinol Metab. 2003 Sep;88(9):4135-8.
  8. Dietrich, J. W., A. Tesche, C. R. Pickardt, U. Mitzdorf: Thyrotropic Feedback Control: Evidence for an Additional Ultrashort Feedback Loop from Fractal Analysis. Cybernetics and Systems 2004; 35(4): 315-31.
  9. Prummel MF, Brokken LJ, Wiersinga WM: Ultra short-loop feedback control of thyrotropin secretion. Thyroid. 2004 Oct; 14(10): 825-9. PMID 15588378
  10. Brokken LJ, Bakker O, Wiersinga WM, Prummel MF: Functional thyrotropin receptor expression in the pituitary folliculo-stellate cell line TtT/GF. Exp Clin Endocrinol Diabetes. 2005 Jan; 113(1): 13-20. PMID 15662590
  11. Dietrich JW, Landgrafe, G, Fotiadou, EH. TSH and Thyrotropic Agonists: Key Actors in Thyroid Homeostasis Journal of Thyroid Research, vol. 2012, Article ID 351864, 29 pages, 2012. doi:10.1155/2012/351864. PMID 23365787.
  12. Hoermann R, Midgley JE, Larisch R, Dietrich JW. Homeostatic Control of the Thyroid-Pituitary Axis: Perspectives for Diagnosis and Treatment. Front Endocrinol (Lausanne). 2015 Nov 20;6:177. doi: 10.3389/fendo.2015.00177. PMID 26635726; PMCID PMC4653296.
  13. Berberich J, Dietrich JW, Hoermann R, Müller MA. Mathematical Modeling of the Pituitary-Thyroid Feedback Loop: Role of a TSH-T(3)-Shunt and Sensitivity Analysis. Front Endocrinol (Lausanne). 2018 Mar 21;9:91. doi: 10.3389/fendo.2018.00091. PMID 29619006; PMCID PMC5871688.

This page was last edited on 29 April 2018, at 17:56.

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