Thyroid function test

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When thyroid function tests are laboratory procedures to check the thyroid function called.

Thyroid function tests are carried out if hyperthyroidism (overactive thyroid gland) or hypothyroidism (underactive thyroid gland) or to control therapy for substitution with thyroid hormones . They can also provide useful information in situations that may be associated with thyroid disease, such as atrial fibrillation or anxiety disorders .

Common thyroid function tests include measurements of TSH levels and / or peripheral thyroid hormones such as thyroxine (T4) and triiodothyronine (T3) from blood serum .

Thyroid hormones

Thyrotropin

The thyrotropin (TSH) level is increased in the case of primary hypothyroidism and decreased in the case of primary hyperthyroidism.

Reference ranges :

Patient group Lower limit Upper limit Unit of measurement
Adult
reference range		 0.3, 0.4, 0.5, 0.6 3.0, 4.0, 4.5, 6.0 mIU / l or μIU / ml
Adults -
reference range (optimal range)		 0.3, 0.5 2.0, 3.0 mIU / l or μIU / ml
children 1.3 19th mIU / l or μIU / ml

Total thyroxine

Total thyroxine (total T 4 ) is generally increased in the case of hyperthyroidism and lowered at a hypothyroidism . Due to increased TBG levels, it is usually slightly increased during pregnancy .

Reference ranges:

Lower limit Upper limit Unit of measurement
4, 5.5 11, 12.3 μg / dL
60 140, 160 nmol / l

Free thyroxine

Free thyroxine (Free T 4 ) is usually increased in hyperthyroidism and decreased in hypothyroidism .

Reference ranges:

Patient group Lower limit Upper limit Unit of measurement
Normal adults 0.7, 0.8 1.4, 1.5, 1.8 ng / dL
9, 10, 12 18, 23 pmol / l
Children 0-3 T 2.0 5.0 ng / dL
26th 65 pmol / l
Children 3–30 T 0.9 2.2 ng / dL
12 30th pmol / l
Children / adolescents
31 T - 18 Y		 0.8 2.0 ng / dL
10 26th pmol / l
Pregnant women 0.5 1.0 ng / dL
6.5 13 pmol / l

Total triiodothyronine

Total triiodothyronine (Total T 3 ) is generally increased in the case of hyperthyroidism and decreased in hypothyroidism.

Reference ranges:

test Lower limit Upper limit Unit of measurement
Total triiodothyronine 60, 75 175, 181 ng / dL
0.9, 1.1 2.5, 2.7 nmol / l

Free triiodothyronine

Free triiodothyronine (Free T 3 ) is generally increased in hyperthyroidism and decreased in hypothyroidism.

Reference ranges:

Patient group Lower limit Upper limit Unit of measurement
Normal adults 0.2 0.5 ng / dL
3.1 7.7 pmol / l
Children 2–16 y 0.1 0.6 ng / dL
1.5 9.2 pmol / l

Overview

Functional situation / illness TSH T 3 T 4 annotation
manifest hyperthyroidism mostly <0.1 mU / l n or ↑ n or ↑ T 3 and / or T 4 ↑
latent hyperthyroidism ↓ n n  
Euthyroidism n n n  
latent hypothyroidism ↑ n n  
manifest hypothyroidism mostly> 10 mU / l n or ↓ n or ↓ T 3 and / or T 4 ↓
secondary hypothyroidism
mostly pituitary insufficiency 		n or ↓ ↓ ↓ Rare
secondary hyperthyroidism
mostly TSH-producing pituitary adenoma 		n or ↑ ↑ ↑ Rare
peripheral thyroid hormone resistance different constellations Rare
pronounced iodine deficiency n ↑ ↓ no thyrostatic treatment
n: normal - ↑: increased - ↓: decreased

Calculated indices of free hormone levels

Transport proteins

An increase in the level of thyroxine-binding globulin (TBG) increases the levels of total thyroxine and total triiodothyronine without actually increasing the production of thyroid hormones. The reference range is 12–30 mg / l.

For thyroglobulin , the reference range is 1.5–30 pmol / l or 1–20 μg / l.

Other binding proteins are transthyretin (thyroxine-binding prealbumin) and albumin .

Diagnostics of protein binding function

Thyroid hormone uptake

The thyroid hormone uptake (T 4 uptake or T 3 uptake) is a measure of the unbound (i.e. not saturated with thyroid hormones) thyroxine-binding globulin in the blood plasma. The unsaturated TBG increases with decreased thyroid hormone levels. Despite the name T 3 -uptake, it is not derived from the T3 mirror.

Reference ranges:

Patient group Lower limit Upper limit Unit of measurement
Women 25th 35 %
During pregnancy 15th 25th %
Men 25th 35 %

Other attachment tests

Mixed parameters

Free T4 index

The free thyroxine index (FTI or T7) results from multiplying the total T 4 level by the T 3 uptake. The FTI is considered to be relatively reliable for disorders of the plasma protein binding of iodothyronines.

The FTI is increased in the case of hyperthyroidism and decreased in the case of hypothyroidism.

Reference ranges:

Patient group Lower limit Upper limit Unit of measurement
Women 1.8 5.0
Men 1.3 4.2

Structural parameters

For special questions, e.g. For the diagnosis of euthyroid sick syndrome or secondary hypothyroidism , for example , calculated structural parameters that describe constant properties of thyroid homeostasis provide useful additional information.

The secretion capacity of the thyroid gland (GT, also known as SPINA-GT) defines the maximum stimulated amount of thyroxine that the thyroid can release in one second. GT is increased in hyperthyroidism and reduced in hypothyroidism. Its reference range is 1.41–8.67 pmol / s.

The total activity of peripheral deiodinases (GD, also SPINA-GD) correlates with the TSH level. It is reduced in the case of non-thyroidal illness syndrome with hypodiodination. Their reference range is 20–40 nmol / s.

With the help of the TSH-Index (TSHI) introduced by Jostel and the standardized TSH-Index (sTSHI) based on it, the thyrotropic function of the anterior pituitary can be assessed quantitatively. The reference range for the TSH index is 1.3–4.1.

The Thyrotroph Thyroid Hormone Sensitivity Index (TTSI, also: Thyrotroph T4 Resistance Index or TT4RI) was developed for the screening diagnosis of thyroid hormone resistance . Like the TSH index, it is calculated from equilibrium levels for TSH and FT4. The reference range is around 100 to 150.

In dogs and cats, the K-FT4 index (also known as the K value ) according to Larsson indicates the likelihood of hypothyroidism. It is calculated with K = 0.7 * FT4 (pmol / l) - cholesterol (mmol / l). If the K value is above 1, hypothyroidism is excluded, if it is below −4 it is probable, and there is a gray area in between. With modern assays, calculating the K value may be unnecessary.

See also

Web links

Individual evidence

  1. ↑ CM Dayan: Interpretation of thyroid function tests . In: Lancet . tape 357 , no. 9256 , February 2001, p. 619-624 , doi : 10.1016 / S0140-6736 (00) 04060-5 , PMID 11558500 .
  2. ↑ a b c d e f g h i j k l m Military Obstetrics & Gynecology> Thyroid Function Tests. ( Memento from November 1, 2013 in the Internet Archive ) In turn citing: Operational Medicine 2001, Health Care in Military Settings, NAVMED P-5139, May 1, 2001, Bureau of Medicine and Surgery, Department of the Navy, 2300 E Street NW , Washington, DC, 20372-5300
  3. ↑ a b c d e f Reference range list from Uppsala University Hospital ("Laborationslista"). Artnr 40284 Sj74a. Issued on April 22, 2008.
  4. ↑ a b c d e f g h i Normal Reference Range Table Normal Reference Range Table from The University of Texas Southwestern Medical Center at Dallas. Used in Interactive Case Study Companion to Pathologic basis of disease.
  5. ↑ a b Blood Test Results - Normal Ranges ( Memento of the original from November 2, 2012 in the Internet Archive ) Info: The archive link was automatically inserted and not yet checked. Please check the original and archive link according to the instructions and then remove this notice. Bloodbook.Com @1@ 2Template: Webachiv / IABot / www.bloodbook.com
  6. ↑ a b c Mary Shomon: The TSH Reference Range Wars: "Normal" What's, Who's Wrong, Who is Right ... About.com. Updated: June 19, 2006. About.com Health's Disease and Condition
  7. ↑ a b Press releases: Thyroid Imbalance? Target Your Numbers ( March 3, 2008 memento on the Internet Archive ) Contacts: Bryan Campbell, American Association of Clinical Endocrinologists
  8. ^ A b Laurence M. Demers, Carole A. Spencer: LMPG: Laboratory Support for the Diagnosis and Monitoring of Thyroid Disease. National Academy of Clinical Biochemistry (USA), 2002, accessed April 13, 2007 . - see Section 2. Pre-analytic factors
  9. ↑ a b c d e f g h i j k l Table 4: Typical reference ranges for serum assays ( Memento from August 20, 2010 in the Internet Archive ) - Thyroid disease Manager
  10. ↑ a b c d G. van der Watt, D. Haarburger, P. Berman: Euthyroid patient with increased serum free thyroxine . In: Clin. Chem. Band 54 , no. 7 , July 2008, p. 1239-1241 , doi : 10.1373 / clinchem.2007.101428 , PMID 18593963 ( clinchem.org ).
  11. ↑ a b c d e f g h i j LAB127: T4, FREE UNC Health Care System
  12. ↑ Derived from a molar mass of 776.87 g / mol
  13. ↑ a b c d e f g h i j Derived from a molar mass of 776.87 g / mol
  14. ↑ a b c d Derived from a molar mass of 650.98 g / mol
  15. ↑ a b M. Cioffi, P. Gazzerro, MT Vietri et al .: Serum concentration of free T3, free T4 and TSH in healthy children . In: J. Pediatr. Endocrinol. Metab. tape 14 , no. 9 , 2001, p. 1635-1639 , doi : 10.1515 / JPEM.2001.14.9.1635 , PMID 11795654 .
  16. ↑ Gerd Herold . Internal Medicine. Cologne 2005, p. 640.
  17. ↑ JW Dietrich, A. Stachon, B. Antic, HH Klein, S. Hering: 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 . In: BMC Endocrine Disorders. 8 (13), 2008. PMID 18851740 .
  18. ↑ a b D. Rosolowska-Huszcz, L. Kozlowska, A. Rydzewski: Influence of low protein diet on nonthyroidal illness syndrome in chronic renal failure . In: Endocrine . tape 27 , no. 3 , August 2005, p. 283-288 , doi : 10.1385 / ENDO: 27: 3: 283 , PMID 16230785 .
  19. ↑ a b S. Liu, J. Ren, Y. Zhao, G. Han, Z. Hong, D. Yan, J. Chen, G. Gu, G. Wang, X. Wang, C. Fan, J. Li : Nonthyroidal Illness Syndrome: Is It Far Away From Crohn's Disease? In: J Clin Gastroenterol. tape 47 , no. 2 , 2013, p. 153-159 , doi : 10.1097 / MCG.0b013e318254ea8a , PMID 22874844 .
  20. ↑ Johannes W. Dietrich, Gabi Landgrafe-Mende, Evelin Wiora, Apostolos Chatzitomaris, Harald H. Klein, John EM Midgley, Rudolf Hoermann: Calculated Parameters of Thyroid Homeostasis: Emerging Tools for Differential Diagnosis and Clinical Research . In: Frontiers in Endocrinology . tape 7 , June 9, 2016, doi : 10.3389 / fendo.2016.00057 .
  21. ↑ a b c J. W. Dietrich: The pituitary-thyroid control circuit . Logos-Verlag, Berlin 2002, ISBN 3-89722-850-5 , 3897228505 ( openlibrary.org ).
  22. ^ J. Dietrich, M. Fischer, J. Jauch, E. Pantke, R. Gärtner, CR Pickardt: SPINA-THYR: A Novel Systems Theoretic Approach to Determine the Secretion Capacity of the Thyroid Gland. In: European Journal of Internal Medicine. 10, Suppl. 1, 5/1999, p. S34.
  23. ^ R. Hoermann, JE Midgley, R. Larisch, JW Dietrich: Is pituitary TSH an adequate measure of thyroid hormone-controlled homoeostasis during thyroxine treatment? In: Eur J Endocrinol. 168 (2), 2013, pp. 271-280. doi: 10.1530 / EJE-12-0819 . PMID 23184912 .
  24. ^ A b A. Jostel, WD Ryder, SM Shalet: The use of thyroid function tests in the diagnosis of hypopituitarism: definition and evaluation of the TSH Index . In: Clin. Endocrinol. (Oxf) . tape 71 , no. 4 , October 2009, p. 529-534 , doi : 10.1111 / j.1365-2265.2009.03534.x , PMID 19226261 .
  25. Jump up ↑ Johannes W. Dietrich, Gabi Landgrafe, Elisavet H. Fotiadou: TSH and Thyrotropic Agonists: Key Actors in Thyroid Homeostasis. In: Journal of Thyroid Research. 2012, 2012, pp. 1–29, doi: 10.1155 / 2012/351864 . PMID 23365787 .
  26. ↑ H. Yagi, J. Pohlenz, Y. Hayashi, A. Sakurai, Refetoff S: Resistance to thyroid hormone caused by two mutant thyroid hormone receptors beta, R243Q and R243W, with marked impairment of function that cannot be explained by altered in vitro 3,5,3'-triiodothyroinine binding affinity. In: J Clin Endocrinol Metab. 82 (5), May 1997, pp. 1608-1614. PMID 9141558
  27. Jump up ↑ J. Pohlenz, RE Weiss, PE Macchia, S. Pannain, T. Lau, H. Ho, S. Refetoff: Five new families with resistance to thyroid hormone not caused by mutations in the thyroid hormone receptor beta gene. In: J Clin Endocrinol Metab. 84 (11), Nov 1999, pp. 3919-3928. PMID 10566629
  28. ^ Ernst-Günther Grünbaum: Clinic of dog diseases. Georg-Thieme-Verlag, Stuttgart / New York 2007, ISBN 978-3-8304-1021-8 .
  29. ↑ Wilfried Kraft: Clinical laboratory diagnostics in veterinary medicine. Schattauer Verlag, 2005, ISBN 3-7945-2308-3 .