Thyroid's secretory capacity: Difference between revisions
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''K''<sub>41</sub>: [[Dissociation constant]] T4-TBG (2e10 l/mol)<br /> |
''K''<sub>41</sub>: [[Dissociation constant]] T4-TBG (2e10 l/mol)<br /> |
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''K''<sub>42</sub>: Dissociation constant T4-TBPA (2e8 l/mol)<br /> |
''K''<sub>42</sub>: Dissociation constant T4-TBPA (2e8 l/mol)<br /> |
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''D''<sub>''T''</sub>: EC<sub>50</sub> for TSH (2.75 mU/l)<ref name=dietrich2002/><ref>Dietrich JW, Stachon A, Antic B, Klein HH, Hering S. The AQUA-FONTIS study: protocol of a multidisciplinary, cross-sectional and prospective longitudinal study for developing standardized diagnostics and classification of non-thyroidal illness syndrome. BMC Endocr Disord |
''D''<sub>''T''</sub>: EC<sub>50</sub> for TSH (2.75 mU/l)<ref name=dietrich2002/><ref>Dietrich JW, Stachon A, Antic B, Klein HH, Hering S. "The AQUA-FONTIS study: protocol of a multidisciplinary, cross-sectional and prospective longitudinal study for developing standardized diagnostics and classification of non-thyroidal illness syndrome. ''BMC Endocr Disord'' 2008 Oct 13;8:13. {{DOI|10.1186/1472-6823-8-13}} PMID 18851740.</ref> |
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=== Reference Range === |
=== Reference Range === |
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== Clinical significance == |
== Clinical significance == |
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GT is elevated in [[hyperthyroidism]] and reduced in [[hypothyroidism]]<ref name=dietrich1999>Dietrich, J., M. Fischer, J. Jauch, E. Pantke, R. Gärtner und C. R. Pickardt (1999). "SPINA-THYR: A Novel Systems Theoretic Approach to Determine the Secretion Capacity of the Thyroid Gland." ''European Journal of Internal Medicine'' 1999; 10(Suppl. 1): S34.</ref><ref>Dietrich JW |
GT is elevated in [[hyperthyroidism]] and reduced in [[hypothyroidism]]<ref name=dietrich1999>Dietrich, J., M. Fischer, J. Jauch, E. Pantke, R. Gärtner und C. R. Pickardt (1999). "SPINA-THYR: A Novel Systems Theoretic Approach to Determine the Secretion Capacity of the Thyroid Gland." ''European Journal of Internal Medicine'' 1999; 10(Suppl. 1): S34.</ref><ref>{{cite journal | author = Dietrich JW | date = Sep 2012 | title = Thyroid storm | url = | journal = Med Klin Intensivmed Notfmed | volume = 107 | issue = 6| pages = 448–53 | doi = 10.1007/s00063-012-0113-2 | pmid = 22878518 }}</ref> and it has been observed to correlate with thyroid volume.<ref name=dietrich2002/> In longitudinal evaluation GT shows lower intraindividual variation than [[Thyroid-stimulating hormone|TSH]], [[free thyroxine|FT4]] or [[Triiodothyronine|FT3]].<ref>Dietrich JW, Landgrafe, G, Fotiadou, EH. [http://www.hindawi.com/journals/jtr/2012/351864/ TSH and Thyrotropic Agonists: Key Actors in Thyroid Homeostasis] ''Journal of Thyroid Research'', vol. 2012: 351864 {{doi:10.1155/2012/351864}}. PMID 23365787</ref> |
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Correlation of SPINA-GT with [[creatinine clearance]] suggested a negative influence of [[Uremia|uremic]] toxins on thyroid biology.<ref>Rosolowska-Huszcz D, Kozlowska L, Rydzewski A |
Correlation of SPINA-GT with [[creatinine clearance]] suggested a negative influence of [[Uremia|uremic]] toxins on thyroid biology.<ref>{{cite journal | author = Rosolowska-Huszcz D, Kozlowska L, Rydzewski A | date = Aug 2005 | title = Influence of low protein diet on nonthyroidal illness syndrome in chronic renal failure | url = | journal = Endocrine | volume = 27 | issue = 3| pages = 283–8 | pmid = 16230785 }}</ref> In the initial phase of major [[Euthyroid sick syndrome|non-thyroidal illness]] SPINA-GT may be temporarily elevated.<ref name="Liu2012">{{cite journal | pmid = 22874844 | title=Nonthyroidal Illness Syndrome: ist it Far Away From Crohn's Disease? | year=2013 | author=Liu S, Ren J, Zhao Y, Han G, Hong Z, Yan D, Chen J, Gu G, Wang G, Wang X, Fan C, Li J | journal=J Clin Gastroenterol. | volume = 47 | issue = 2 | pages = 153–9 | doi = 10.1097/MCG.0b013e318254ea8a}}</ref> |
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==See also== |
==See also== |
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Revision as of 13:58, 16 July 2015
Thyroid's secretory capacity (GT, also referred to as thyroid's incretory capacity, maximum thyroid hormone output, T4 output or, if calculated from levels of thyroid hormones, as SPINA-GT) is the maximum stimulated amount of thyroxine that the thyroid can produce in a given time-unit (e.g. one second).[1]
How to determine GT
Experimentally, GT can be determined by stimulating the thyroid with high a thyrotropin concentration and measuring its output in terms of T4 production.
In vivo, GT can also be estimated from equilibrium levels of TSH and T4 or free T4. In this case it is calculated with
![{\displaystyle {\hat {G}}_{T}={{\beta _{T}(D_{T}+[TSH])(1+K_{41}[TBG]+K_{42}[TBPA])[FT_{4}]} \over {\alpha _{T}[TSH]}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/ce585704418696df1a09776f5783982f4e8ccfda)
or
![{\displaystyle {\hat {G}}_{T}={{\beta _{T}(D_{T}+[TSH])[TT_{4}]} \over {\alpha _{T}[TSH]}}}](https://wikimedia.org/api/rest_v1/media/math/render/svg/49096b88c80968270eecf5ed5c78c682d4b3fcf5)
: Theoretical (apparent) secretory capacity (SPINA-GT)
: Dilution factor for T4 (reciprocal of apparent volume of distribution, 0.1 l−1)
: Clearance exponent for T4 (1.1e-6 sec−1)
K41: Dissociation constant T4-TBG (2e10 l/mol)
K42: Dissociation constant T4-TBPA (2e8 l/mol)
DT: EC50 for TSH (2.75 mU/l)[1][2]
Reference Range
| Lower limit | Upper limit | Unit |
| 1.41[1] | 8.67[1] | pmol/s |
The equations and their parameters are calibrated for adult humans with a body mass of 70 kg and a plasma volume of ca. 2.5 l.[1]
Clinical significance
GT is elevated in hyperthyroidism and reduced in hypothyroidism[3][4] and it has been observed to correlate with thyroid volume.[1] In longitudinal evaluation GT shows lower intraindividual variation than TSH, FT4 or FT3.[5] Correlation of SPINA-GT with creatinine clearance suggested a negative influence of uremic toxins on thyroid biology.[6] In the initial phase of major non-thyroidal illness SPINA-GT may be temporarily elevated.[7]
See also
External links
References
- ^ a b c d e f Dietrich, J. W. (2002). Der Hypophysen-Schilddrüsen-Regelkreis. Berlin, Germany: Logos-Verlag Berlin. ISBN 978-3-89722-850-4. OCLC 50451543. 3897228505Template:Inconsistent citations
{{cite book}}: CS1 maint: postscript (link) - ^ Dietrich JW, Stachon A, Antic B, Klein HH, Hering S. "The AQUA-FONTIS study: protocol of a multidisciplinary, cross-sectional and prospective longitudinal study for developing standardized diagnostics and classification of non-thyroidal illness syndrome. BMC Endocr Disord 2008 Oct 13;8:13. doi:10.1186/1472-6823-8-13 PMID 18851740.
- ^ Dietrich, J., M. Fischer, J. Jauch, E. Pantke, R. Gärtner und C. R. Pickardt (1999). "SPINA-THYR: A Novel Systems Theoretic Approach to Determine the Secretion Capacity of the Thyroid Gland." European Journal of Internal Medicine 1999; 10(Suppl. 1): S34.
- ^ Dietrich JW (Sep 2012). "Thyroid storm". Med Klin Intensivmed Notfmed. 107 (6): 448–53. doi:10.1007/s00063-012-0113-2. PMID 22878518.
- ^ Dietrich JW, Landgrafe, G, Fotiadou, EH. TSH and Thyrotropic Agonists: Key Actors in Thyroid Homeostasis Journal of Thyroid Research, vol. 2012: 351864 {{doi:10.1155/2012/351864}}. PMID 23365787
- ^ Rosolowska-Huszcz D, Kozlowska L, Rydzewski A (Aug 2005). "Influence of low protein diet on nonthyroidal illness syndrome in chronic renal failure". Endocrine. 27 (3): 283–8. PMID 16230785.
{{cite journal}}: CS1 maint: multiple names: authors list (link) - ^ Liu S, Ren J, Zhao Y, Han G, Hong Z, Yan D, Chen J, Gu G, Wang G, Wang X, Fan C, Li J (2013). "Nonthyroidal Illness Syndrome: ist it Far Away From Crohn's Disease?". J Clin Gastroenterol. 47 (2): 153–9. doi:10.1097/MCG.0b013e318254ea8a. PMID 22874844.
{{cite journal}}: CS1 maint: multiple names: authors list (link)