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thyroid-stimulating hormone (TSH) in serum; thyrotropin in serum

Indications: - evaluation of thyroid function - thyrotoxicosis - hyperthyroidism - iodine-induced thyrotoxicosis - iodinated contrast - amiodarone - other medications (see thyrotoxicosis) - hypothyroidism - screening for thyroid disease - monitoring or assessment of thyroid disease - treatment of hypothyroidism - thyrotoxicosis Reference values: - 0.46 to 4.98 uIU/mL - < 2.5 uIU/mL in 1st trimester of pregnancy [4] - > 20 uIU/mL establishes diagnosis of primary hypothyroidism - mean serum TSH increases over time in adults (1.49 to 1.81 mIU/L over 13 years) - elderly >= 80 years of age: 0.5-8.0 uIU/mL [10,13] Clinical significance: - serum TSH is a screening tool - if serum TSH is high, minimally measure serum T4 [10] - if serum TSH is low, minimally measure serum T3 & serum T4 - serum TSH is the most sensitive indicator of thyroid function in ambulatory patients with intact pituitary function [10] - for diagnostic purposes, the serum TSH results should be used in conjunction with other data e.g., symptoms, results of other thyroid tests, clinical impressions, etc. - in women, high or low normal serum TSH may be harbinger of hypothyroidsim or hyperthyroidism, respectively [5] - in men, high normal serum TSH may be harbinger of hypothyroidism [5] - serum TSH is used to monitor therapeutic range of levothyroxine therapy in patients with hypothyroidism & intact pituitary function [10] - higher serum TSH & lower serum free T4 in elderly Askenazni Jews is associated with extreme longevity [12] - higher serum TSH within the reference range may decrease risk of stroke [14] Decreases: 1) thyrotoxicosis a) hyperthyroidism - subclinical hyperthyroidism with or without thyroid nodule b) iodine-induced thyrotoxicosis - iodinated contrast - amiodarone c) other medications (see thyrotoxicosis) 2) pituitary insufficiency - euthyroid sick syndrome (blunted TSH response to TRH) 3) hypothalamic insufficiency (rare) 4) high doses of biotin may falsely lower serum TSH [15] Increases: 1) primary hypothyroidism 2) inadequate thyroid hormone replacement in a patient with hypothyroidism 3) TSH-secreting pituitary tumor (rare) Principle: The IMx hTSH assay is based on the Microparticle Enzyme Immunoassay (MEIA) technology. The reagents are added to the reaction cell in the following sequence: 1) The probe/electrode assembly delivers the sample & Anti-hTSH Coated Microparticles to the incubation well of the reaction cell. 2) The hTSH binds to the Anti-hTSH Coated Microparticles forming an antibody-antigen complex. 3) An aliquot of the reaction mixture containing the antibody- antigen complex bound to the microparticles is transferred to the glass fiber matrix. The microparticles bind irreversibly to the glass fiber matrix. 4) The matrix is washed to remove unbound materials. 5) The Anti-hTSH: Alkaline Phosphatase is dispensed onto the matrix & binds with the antibody-antigen complex. 6) The matrix is washed to remove unbound materials. 7) The substrate, 4-Methyllumbelliferyl Phosphate, is added to the matrix & the fluorescent product is measured by the MEIA optical assembly. Specimen: 1) Serum specimens & plasma (heparin or EDTA) may be used. 2) If the assay is to be performed within 24 hours after collection, the specimen should be stored in the refrigerator at 2-8 C. If the testing will be delayed more than 24 hours, the specimen should be frozen. Mix thoroughly after thawing to ensure consistency in the results. Avoid repeated freezing & thawing. 3) Specimens showing particulate matter , erythrocytes, or turbidity should be centrifuged before testing. SAMPLE VOLUME: 150 uL of specimen is the minimum volume require to perform the assay.

Related

thyroid-stimulating hormone (TSH) or thyrotropin thyroxine [T4] (free) in serum thyroxine [T4] (total) in serum

Specific

thyrotropin(TSH).long-acting in serum/plasma

General

thyroid-stimulating hormone (TSH) in body fluid; thyrotropin in body fluid thyroid function test

References

  1. Abbott Laboratories ,Diagnostic Division ,Abbott Park, IL 60064 Thyroid function, IMx TSH, AUGUST 1990.
  2. IMx System Operation Manual, Abbott Diagnostics, a Division of Abbott Laboratories, Abbott Park, IL. 60064, AUGUST 1988.
  3. IMx System Assay Manual, Abbott Diagnostics, a Division of Abbott Laboratories, Abbott Park, IL. 60064, AUGUST 1988.
  4. Negro R et al. Increased pregnancy loss rate in thyroid antibody negative women with TSH levels between 2.5 and 5.0 in the first trimester of pregnancy. J Clin Endocrinol Metab 2010 Sep; 95:E44 PMID: 20534758
  5. Asvold BO et al. Serum TSH within the reference range as a predictor of future hypothyroidism and hyperthyroidism: 11-year follow-up of the HUNT study in Norway. J Clin Endocrinol Metab 2012 Jan; 97:93 PMID: 22049180
  6. Bremner AP et al. Age-related changes in thyroid function: A longitudinal study of a community-based cohort. J Clin Endocrinol Metab 2012 May; 97:1554 PMID: 22344200
  7. Thyroid Stimulating Hormone Laboratory Test Directory ARUP: 70145
  8. TSH 3rd Generation Laboratory Test Directory ARUP: 70225
  9. Panel of 3 tests Laboratory Test Directory ARUP: 2005415
  10. Medical Knowledge Self Assessment Program (MKSAP) 16, 17, 19. American College of Physicians, Philadelphia 2012, 2015, 2022
  11. Geriatric Review Syllabus, 8th edition (GRS8) Durso SC and Sullivan GN (eds) American Geriatrics Society, 2013
  12. Atzmon G, Barzilai N, Hollowell JG, Surks MI, Gabriely I. Extreme longevity is associated with increased serum thyrotropin. J Clin Endocrinol Metab. 2009 Apr;94(4):1251-4 PMID: 19158193
  13. Tabatabaie V, Surks MI. The aging thyroid. Curr Opin Endocrinol Diabetes Obes. 2013 Review. PMID: 23974775
  14. Chaker L, Baumgartner C, den Elzen WP et al Thyroid Function within the Reference Range and the Risk of Stroke: An Individual Participant Data Analysis. J Clin Endocrinol Metab. 2016 Sep 7 PMID: 27603906
  15. Al-Salameh A et al A Somewhat Bizarre Case of Graves Disease Due to Vitamin Treatment. J Endo Soc. 2017;1(5):431-435. Not indexed in PubMed http://www.medscape.com/viewarticle/880576_2

Component-of

anemia panel anterior pituitary evaluation panel general health panel hypertension panel thyroid panel