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词条 Sum activity of peripheral deiodinases
释义

  1. How to determine GD

     Reference range 

  2. Clinical significance

  3. See also

  4. References

  5. External links

{{Infobox diagnostic
| name = Sum activity of peripheral deiodinases
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| LOINC = 82367-4
| reference_range = 20–40 nmol/s
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The sum activity of peripheral deiodinases (GD, also referred to as deiodination capacity, total deiodinase activity or, if calculated from levels of thyroid hormones, as SPINA-GD) is the maximum amount of triiodothyronine produced per time-unit under conditions of substrate saturation.[1] It is assumed to reflect the activity of deiodinases outside the central nervous system and other isolated compartments. GD is therefore expected to reflect predominantly the activity of type I deiodinase.

How to determine GD

GD can be determined experimentally by exposing a cell culture system to saturating concentrations of T4 and measuring the T3 production. Whole body deiodination activity can be assessed by measuring production of radioactive iodine after loading the organism with marked thyroxine.

However, both approaches are faced with draw-backs. Measuring deiodination in cell culture delivers little, if any, information on total deiodination activity. Using marked thyroxine exposes the body to thyrotoxicosis and radioactivity. Additionally, it is not possible to differentiate step-up reactions resulting in T3 production from the step-down reaction catalyzed by type 3 deiodination, which mediates production of reverse T3.

In vivo, it may therefore be beneficial to estimate GD from equilibrium levels of T4 and T3. It is obtained with

or

: Dilution factor for T3 (reciprocal of apparent volume of distribution, 0.026 l−1)
: Clearance exponent for T3 (8e-6 sec−1)
KM1: Dissociation constant of type-1-deiodinase (5e-7 mol/l)
K30: Dissociation constant T3-TBG (2e9 l/mol)[2]

Reference range

Lower limitUpper limitUnit
20[2] 40[2] nmol/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.[2]

Clinical significance

SPINA-GD correlates with resting energy expenditure[3], body mass index[2][4][5] and thyrotropin levels in humans,[6][7] and it is reduced in nonthyroidal illness with hypodeiodination.[4][8][9][10][11]

Recent research revealed total deiodinase activity to be higher in hypothyroid patients as long as thyroid tissue is still present,.[7] This effect may ensue from the existence of an effective TSH-deiodinase axis or TSH-T3 shunt. After total thyroidectomy or high-dose radioiodine therapy (e.g. in treated thyroid cancer) as well as after initiation of substitution therapy with levothyroxine the activity of step-up deiodinases decreases and the correlation of SPINA-GD to thyrotropin concentration is lost.[12] SPINA-GD is also reduced in certain chronic diseases, e.g. chronic fatigue syndrome.[13] In Graves's disease, initially elevated SPINA-GD decreaes with antithyroid treatment in parallel to declining TSH receptor autoantibody titres[3].

In hyperthyroid[14] men both SPINA-GT and SPINA-GD negatively correlate to erectile function, intercourse satisfaction, orgasmic function and sexual desire. Substitution with selenomethionine results in increased SPINA-GD in subjects with autoimmune thyroiditis[15][16].

Deiodination capacity proved to be an inpedendent predictor of substitution dose in a trial with over 300 patients on replacement therapy with levothyroxine.[17]

See also

  • Thyroid function tests
  • Thyroid's secretory capacity
  • Jostel's TSH index
  • Thyrotroph Thyroid Hormone Sensitivity Index
  • SimThyr

References

1. ^{{cite journal | vauthors = Dietrich JW, Landgrafe-Mende G, Wiora E, Chatzitomaris A, Klein HH, Midgley JE, Hoermann R | title = Calculated Parameters of Thyroid Homeostasis: Emerging Tools for Differential Diagnosis and Clinical Research | journal = Frontiers in Endocrinology | volume = 7 | pages = 57 | date = 9 June 2016 | pmid = 27375554 | pmc = 4899439 | doi = 10.3389/fendo.2016.00057 }}
2. ^1 2 3 4 {{cite book | vauthors = Dietrich JW | title = Der Hypophysen-Schilddrüsen-Regelkreis | publisher = Logos-Verlag Berlin | isbn = 978-3-89722-850-4 | location = Berlin, Germany | url = http://openlibrary.org/books/OL24586469M/Der_Hypophysen-Schilddrüsen-Regelkreis | date = 2002 | oclc = 50451543 }}
3. ^1 {{cite journal |last1=Kim |first1=Min Joo |last2=Cho |first2=Sun Wook |last3=Choi |first3=Sumin |last4=Ju |first4=Dal Lae |last5=Park |first5=Do Joon |last6=Park |first6=Young Joo |title=Changes in Body Compositions and Basal Metabolic Rates during Treatment of Graves' Disease |journal=International Journal of Endocrinology |date=2018 |volume=2018 |pages=9863050 |doi=10.1155/2018/9863050|pmid=29853888 |pmc=5960571 }}
4. ^1 {{cite journal | vauthors = Liu S, Ren J, Zhao Y, Han G, Hong Z, Yan D, Chen J, Gu G, Wang G, Wang X, Fan C, Li J | title = Nonthyroidal illness syndrome: is it far away from Crohn's disease? | journal = Journal of Clinical Gastroenterology | volume = 47 | issue = 2 | pages = 153–9 | date = February 2013 | pmid = 22874844 | doi = 10.1097/MCG.0b013e318254ea8a }}
5. ^{{cite journal | vauthors = Dietrich JW, Landgrafe G, Fotiadou EH | title = TSH and Thyrotropic Agonists: Key Actors in Thyroid Homeostasis | journal = Journal of Thyroid Research | volume = 2012 | issue = | pages = 1–29 | year = 2012 | pmid = 23365787 | pmc = 3544290 | doi = 10.1155/2012/351864 | url = http://www.hindawi.com/journals/jtr/2012/351864/ }}
6. ^{{cite journal | vauthors = Hoermann R, Midgley JE, Larisch R, Dietrich JW | title = Is pituitary TSH an adequate measure of thyroid hormone-controlled homoeostasis during thyroxine treatment? | journal = European Journal of Endocrinology | volume = 168 | issue = 2 | pages = 271–80 | date = February 2013 | pmid = 23184912 | doi = 10.1530/EJE-12-0819 }}
7. ^1 {{cite journal | vauthors = Hoermann R, Midgley JE, Giacobino A, Eckl WA, Wahl HG, Dietrich JW, Larisch R | title = Homeostatic equilibria between free thyroid hormones and pituitary thyrotropin are modulated by various influences including age, body mass index and treatment | journal = Clinical Endocrinology | volume = 81 | issue = 6 | pages = 907–15 | date = December 2014 | pmid = 24953754 | doi = 10.1111/cen.12527 }}
8. ^{{cite journal | vauthors = Rosolowska-Huszcz D, Kozlowska L, Rydzewski A | title = Influence of low protein diet on nonthyroidal illness syndrome in chronic renal failure | journal = Endocrine | volume = 27 | issue = 3 | pages = 283–8 | date = August 2005 | pmid = 16230785 | doi = 10.1385/ENDO:27:3:283 }}
9. ^{{cite journal | vauthors = Han G, Ren J, Liu S, Gu G, Ren H, Yan D, Chen J, Wang G, Zhou B, Wu X, Yuan Y, Li J | title = Nonthyroidal illness syndrome in enterocutaneous fistulas | journal = American Journal of Surgery | volume = 206 | issue = 3 | pages = 386–92 | date = September 2013 | pmid = 23809674 | doi = 10.1016/j.amjsurg.2012.12.011 }}
10. ^{{cite journal | vauthors = Dietrich JW, Müller P, Schiedat F, Schlömicher M, Strauch J, Chatzitomaris A, Klein HH, Mügge A, Köhrle J, Rijntjes E, Lehmphul I | title = Nonthyroidal Illness Syndrome in Cardiac Illness Involves Elevated Concentrations of 3,5-Diiodothyronine and Correlates with Atrial Remodeling | journal = European Thyroid Journal | volume = 4 | issue = 2 | pages = 129–37 | date = June 2015 | pmid = 26279999 | pmc = 4521060 | doi = 10.1159/000381543 | url = http://www.karger.com/Article/FullText/381543 }}
11. ^{{cite journal | vauthors = Fan S, Ni X, Wang J, Zhang Y, Tao S, Chen M, Li Y, Li J | title = Low Triiodothyronine Syndrome in Patients With Radiation Enteritis: Risk Factors and Clinical Outcomes an Observational Study | journal = Medicine | volume = 95 | issue = 6 | pages = e2640 | date = February 2016 | pmid = 26871787 | pmc = 4753882 | doi = 10.1097/MD.0000000000002640 }}
12. ^{{cite journal | vauthors = Hoermann R, Midgley JE, Larisch R, Dietrich JW | title = Advances in applied homeostatic modelling of the relationship between thyrotropin and free thyroxine | journal = PLOS One | volume = 12 | issue = 11 | pages = e0187232 | date = 2017 | pmid = 29155897 | doi = 10.1371/journal.pone.0187232 | pmc=5695809| bibcode = 2017PLoSO..1287232H }}
13. ^{{cite journal|last1=Ruiz-Núñez|first1=Begoña|last2=Tarasse|first2=Rabab|last3=Vogelaar|first3=Emar F.|last4=Janneke Dijck-Brouwer|first4=D. A.|last5=Muskiet|first5=Frits A. J.|title=Higher Prevalence of "Low T3 Syndrome" in Patients With Chronic Fatigue Syndrome: A Case–Control Study|journal=Frontiers in Endocrinology|date=20 March 2018|volume=9|pages=97|doi=10.3389/fendo.2018.00097|pmid=29615976|pmc=5869352}}
14. ^{{cite journal |last1=Krysiak |first1=R |last2=Marek |first2=B |last3=Okopień |first3=B |title=Sexual function and depressive symptoms in men with overt hyperthyroidism. |journal=Endokrynologia Polska |date=2019 |volume=70 |issue=1 |pages=64-71 |doi=10.5603/EP.a2018.0069 |pmid=30307028}}
15. ^{{cite journal |last1=Krysiak |first1=Robert |last2=Szkróbka |first2=Witold |last3=Okopień |first3=Bogusław |title=The effect of vitamin D and selenomethionine on thyroid antibody titers, hypothalamic-pituitary-thyroid axis activity and thyroid function tests in men with Hashimoto's thyroiditis: a pilot study |journal=Pharmacological Reports |date=October 2018 |volume=71 |issue=2 |pages=243-7 |doi=10.1016/j.pharep.2018.10.012 |pmid=30818086}}
16. ^{{cite journal |last1=Krysiak |first1=Robert |last2=Kowalcze |first2=Karolina |last3=Okopień |first3=Bogusław |title=Selenomethionine potentiates the impact of vitamin D on thyroid autoimmunity in euthyroid women with Hashimoto's thyroiditis and low vitamin D status |journal=Pharmacological Reports |date=December 2018 |volume = 71 |issue = 2 |pages = 367-73 |doi=10.1016/j.pharep.2018.12.006 |pmid=30844687}}
17. ^{{cite journal | vauthors = Midgley JE, Larisch R, Dietrich JW, Hoermann R | title = Variation in the biochemical response to l-thyroxine therapy and relationship with peripheral thyroid hormone conversion efficiency | journal = Endocrine Connections | volume = 4 | issue = 4 | pages = 196–205 | date = December 2015 | pmid = 26335522 | pmc = 4557078 | doi = 10.1530/EC-15-0056 }}
{{Use dmy dates|date=April 2017}}

External links

  • SPINA Thyr: Open source software for calculating GT and GD
  • Package "[https://cran.r-project.org/package=SPINA SPINA]" for the statistical environment R

6 : Chemical pathology|Blood tests|Endocrine procedures|Thyroidological methods|Thyroid homeostasis|Structure parameters of thyroid function
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