thyroid-stimulating hormone (TSH) in serum; thyrotropin in serum
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Indications
- evaluation of thyroid function
- thyrotoxicosis
- hyperthyroidism
- iodine-induced thyrotoxicosis
- other medications (see thyrotoxicosis)
- hypothyroidism
- thyrotoxicosis
- screening for thyroid disease
- monitoring or assessment of thyroid disease
- treatment of hypothyroidism
- thyrotoxicosis
Reference interval
- 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]
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:
- The probe/electrode assembly delivers the sample & Anti-hTSH Coated Microparticles to the incubation well of the reaction cell.
- The hTSH binds to the Anti-hTSH Coated Microparticles forming an antibody-antigen complex.
- 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.
- The matrix is washed to remove unbound materials.
- The Anti-hTSH: Alkaline Phosphatase is dispensed onto the matrix & binds with the antibody-antigen complex.
- The matrix is washed to remove unbound materials.
- The substrate, 4-Methyllumbelliferyl Phosphate, is added to the matrix & the fluorescent product is measured by the MEIA optical assembly.
Clinical significance
- serum TSH is a screening tool
- 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]
Increases
- primary hypothyroidism
- inadequate thyroid hormone replacement in a patient with hypothyroidism
- TSH-secreting pituitary tumor (rare)
Decreases
- thyrotoxicosis
- hyperthyroidism
- subclinical hyperthyroidism with or without thyroid nodule
- iodine-induced thyrotoxicosis
- other medications (see thyrotoxicosis)
- hyperthyroidism
- pituitary insufficiency
- euthyroid sick syndrome (blunted TSH response to TRH)
- hypothalamic insufficiency (rare)
- high doses of biotin may falsely lower serum TSH[15]
Specimen
- Serum specimens & plasma (heparin or EDTA) may be used.
- 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.
- 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.
More general terms
More specific terms
Additional terms
- thyroid-stimulating hormone (TSH) or thyrotropin
- thyroxine [T4] (free) in serum
- thyroxine [T4] (total) in serum
Component of
- anterior pituitary evaluation panel
- thyroid panel
- hypertension panel
- general health panel
- anemia panel
References
- ↑ Abbott Laboratories ,Diagnostic Division ,Abbott Park, IL 60064 Thyroid function, IMx TSH, AUGUST 1990.
- ↑ IMx System Operation Manual, Abbott Diagnostics, a Division of Abbott Laboratories, Abbott Park, IL. 60064, AUGUST 1988.
- ↑ IMx System Assay Manual, Abbott Diagnostics, a Division of Abbott Laboratories, Abbott Park, IL. 60064, AUGUST 1988.
- ↑ 4.0 4.1 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: https://www.ncbi.nlm.nih.gov/pubmed/20534758
- ↑ 5.0 5.1 5.2 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: https://www.ncbi.nlm.nih.gov/pubmed/22049180
- ↑ 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: https://www.ncbi.nlm.nih.gov/pubmed/22344200
- ↑ Thyroid Stimulating Hormone Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0070145.jsp
- ↑ TSH 3rd Generation Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0070225.jsp
- ↑ Panel of 3 tests Laboratory Test Directory ARUP: http://www.aruplab.com/guides/ug/tests/0000000.jsp
- ↑ 10.0 10.1 10.2 10.3 10.4 Medical Knowledge Self Assessment Program (MKSAP) 16, 17, 19. American College of Physicians, Philadelphia 2012, 2015, 2022
- ↑ Geriatric Review Syllabus, 8th edition (GRS8) Durso SC and Sullivan GN (eds) American Geriatrics Society, 2013
- ↑ 12.0 12.1 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: https://www.ncbi.nlm.nih.gov/pubmed/19158193
- ↑ 13.0 13.1 Tabatabaie V, Surks MI. The aging thyroid. Curr Opin Endocrinol Diabetes Obes. 2013 Review. PMID: https://www.ncbi.nlm.nih.gov/pubmed/23974775
- ↑ 14.0 14.1 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: https://www.ncbi.nlm.nih.gov/pubmed/27603906
- ↑ 15.0 15.1 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