Subclinical hypothyroidism: Difference between revisions

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In [[medicine]], '''subclinical hypothyroidism''' is an elevated [[thyrotropin]] (TSH) concentration can maintain a normal or near normal [[thyroxine ]](T4) concentration.<ref name="pmid14722150">{{cite journal| author=Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH et al.| title=Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. | journal=JAMA | year= 2004 | volume= 291 | issue= 2 | pages= 228-38 | pmid=14722150 | doi=10.1001/jama.291.2.228 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14722150  }} </ref><ref name="pmid22273398">{{cite journal| author=Cooper DS, Biondi B| title=Subclinical thyroid disease. | journal=Lancet | year= 2012 | volume= 379 | issue= 9821 | pages= 1142-54 | pmid=22273398 | doi=10.1016/S0140-6736(11)60276-6 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22273398  }} </ref>
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In [[medicine]], '''subclinical hypothyroidism''' is an elevated ''thyrotropin'' (a.k.a. thyroid stimulating hormone, or TSH) concentration can maintain a normal or near normal [[thyroxine ]](T4) concentration.<ref name="pmid14722150">{{cite journal| author=Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH et al.| title=Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. | journal=JAMA | year= 2004 | volume= 291 | issue= 2 | pages= 228-38 | pmid=14722150 | doi=10.1001/jama.291.2.228 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14722150  }} </ref><ref name="pmid22273398">{{cite journal| author=Cooper DS, Biondi B| title=Subclinical thyroid disease. | journal=Lancet | year= 2012 | volume= 379 | issue= 9821 | pages= 1142-54 | pmid=22273398 | doi=10.1016/S0140-6736(11)60276-6 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22273398  }} </ref>


==Prognosis==
==Prognosis==
"Subclinical hypothyroidism is  associated with an increased risk of CHD events and CHD mortality in  those with higher TSH levels, particularly in those with a TSH  concentration of 10 mIU/L or greater" according to a individual patient data [[meta-analysis]]. <ref  name="pmid20858880">{{cite journal| author=Rodondi N, den Elzen WP,  Bauer DC, Cappola AR, Razvi S, Walsh JP et al.| title=Subclinical  hypothyroidism and the risk of coronary heart disease and mortality. |  journal=JAMA | year= 2010 | volume= 304 | issue= 12 | pages= 1365-74 |  pmid=20858880 | doi=10.1001/jama.2010.1361 | pmc= |  url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20858880  }}  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21169625  Review in: Evid Based Med. 2011 Feb;16(1):31-2] </ref>
"Subclinical hypothyroidism is  associated with an increased risk of congenital heart disease (CHD) events and CHD mortality in  those with higher TSH levels, particularly in those with a TSH  concentration of 10 mIU/L or greater" according to a individual patient data [[meta-analysis]]. <ref  name="pmid20858880">{{cite journal| author=Rodondi N, den Elzen WP,  Bauer DC, Cappola AR, Razvi S, Walsh JP et al.| title=Subclinical  hypothyroidism and the risk of coronary heart disease and mortality. |  journal=JAMA | year= 2010 | volume= 304 | issue= 12 | pages= 1365-74 |  pmid=20858880 | doi=10.1001/jama.2010.1361 | pmc= |  url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20858880  }}  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21169625  Review in: Evid Based Med. 2011 Feb;16(1):31-2] </ref>


==Thyrotropin level==
==Thyrotropin level==
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The thyrotropin level helps predict progression to overt [[hypothyroidism]].<ref name="pmid17646608">{{cite journal| author=Meyerovitch J, Rotman-Pikielny P, Sherf M, Battat E, Levy Y, Surks MI| title=Serum thyrotropin measurements in the community: five-year follow-up in a large network of primary care physicians. | journal=Arch Intern Med | year= 2007 | volume= 167 | issue= 14 | pages= 1533-8 | pmid=17646608 | doi=10.1001/archinte.167.14.1533 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17646608  }} </ref>
The thyrotropin level helps predict progression to overt [[hypothyroidism]].<ref name="pmid17646608"/>


===Antithyroid peroxidase antibodies===
===Antithyroid peroxidase antibodies===
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Diagnostic accuracy for predicting over [[hypothyroidism]] has been reported.
Diagnostic accuracy for predicting over [[hypothyroidism]] has been reported.


Diez et al found that among patients with TSH > 5, antibodies > 20 U/ml were significant predictors of hypothyrodism after 3.5 years of follow-up in which 26% developed overt hypothyroidism, but ''not'' after controlling for initial [[thyrotropin]] level.<ref name="pmid15472181">{{cite journal|  author=Díez JJ, Iglesias P| title=Spontaneous subclinical  hypothyroidism in patients older than 55 years: an analysis of natural  course and risk factors for the development of overt thyroid failure. |  journal=J Clin Endocrinol Metab | year= 2004 | volume= 89 | issue= 10 |  pages= 4890-7 | pmid=15472181 | doi=10.1210/jc.2003-032061 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15472181  }} </ref>
Diez et al found that among patients with TSH > 5, antibodies > 20 U/ml were significant predictors of hypothyrodism after 3.5 years of follow-up in which 26% developed overt hypothyroidism, but ''not'' after controlling for initial [[thyrotropin]] level.<ref name="pmid15472181"/>
* Sensitivity 93%
* Sensitivity 93%
* Specificity 30%
* Specificity 30%
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* Negative predictive value 92%
* Negative predictive value 92%


Walsh et al found that among patients with TSH> 4, antibodies > 35 U/ml were significant predictors of hypothyrodism after 13 years of follow-up in which 31% developed overt hypothyroidism, but ''not'' after controlling for initial [[thyrotropin]] level.<ref  name="pmid20097710">{{cite journal| author=Walsh JP, Bremner AP,  Feddema P, Leedman PJ, Brown SJ, O'Leary P| title=Thyrotropin and  thyroid antibodies as predictors of hypothyroidism: a 13-year,  longitudinal study of a community-based cohort using current immunoassay  techniques. | journal=J Clin Endocrinol Metab | year= 2010 | volume= 95  | issue= 3 | pages= 1095-104 | pmid=20097710 | doi=10.1210/jc.2009-1977  | pmc= |  url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20097710  }} </ref>
Walsh et al found that among patients with TSH> 4, antibodies > 35 U/ml were significant predictors of hypothyrodism after 13 years of follow-up in which 31% developed overt hypothyroidism, but ''not'' after controlling for initial [[thyrotropin]] level.<ref  name="pmid20097710"/>
* Sensitivity 84%
* Sensitivity 84%
* Specificity 30%
* Specificity 30%
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==Treatment==
==Treatment==
"In current RCTs, levothyroxine  replacement therapy for subclinical hypothyroidism did not result in  improved survival or decreased cardiovascular morbidity" according to a [[meta-analysis]] by the [[Cochrane Collaboration]]. <ref  name="pmid17636722">{{cite journal| author=Villar HC, Saconato H,  Valente O, Atallah AN| title=Thyroid hormone replacement for subclinical  hypothyroidism. | journal=Cochrane Database Syst Rev | year= 2007 |  volume=  | issue= 3 | pages= CD003419 | pmid=17636722 |  doi=10.1002/14651858.CD003419.pub2 | pmc= | url= }}  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18170994  Review in: ACP J Club. 2008 Jan-Feb;148(1):7]  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18170993  Review in: ACP J Club. 2008 Jan-Feb;148(1):6]  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18234930  Review in: Evid Based Med. 2008 Feb;13(1):22] </ref> Subsequent [[randomized controlled trial]]s have been positive using 100 microg T4 orally per day<ref name="pmid17299073">{{cite journal| author=Razvi S, Ingoe L, Keeka G, Oates C, McMillan C, Weaver JU| title=The beneficial effect of L-thyroxine on cardiovascular risk factors, endothelial function, and quality of life in subclinical hypothyroidism: randomized, crossover trial. | journal=J Clin Endocrinol Metab | year= 2007 | volume= 92 | issue= 5 | pages= 1715-23 | pmid=17299073 | doi=10.1210/jc.2006-1869 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17299073  }} </ref> and negative using 25 microg T4 orally per day<ref name="pmid20501682">{{cite journal| author=Parle J, Roberts L, Wilson S, Pattison H, Roalfe A, Haque MS et al.| title=A randomized controlled trial of the effect of thyroxine replacement on cognitive function in community-living elderly subjects with subclinical hypothyroidism: the Birmingham Elderly Thyroid study. | journal=J Clin Endocrinol Metab | year= 2010 | volume= 95 | issue= 8 | pages= 3623-32 | pmid=20501682 | doi=10.1210/jc.2009-2571 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20501682  }} </ref>.
"In current RCTs, levothyroxine  replacement therapy for subclinical hypothyroidism did not result in  improved survival or decreased cardiovascular morbidity" according to a [[meta-analysis]] by the [[Cochrane Collaboration]]. <ref  name="pmid17636722">{{cite journal| author=Villar HC, Saconato H,  Valente O, Atallah AN| title=Thyroid hormone replacement for subclinical  hypothyroidism. | journal=Cochrane Database Syst Rev | year= 2007 |  volume=  | issue= 3 | pages= CD003419 | pmid=17636722 |  doi=10.1002/14651858.CD003419.pub2 | pmc= | url= }}  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18170994  Review in: ACP J Club. 2008 Jan-Feb;148(1):7]  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18170993  Review in: ACP J Club. 2008 Jan-Feb;148(1):6]  [http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=18234930  Review in: Evid Based Med. 2008 Feb;13(1):22] </ref>


[[Clinical practice guideline]]s guide management.
Subsequent [[randomized controlled trial]]s have been positive using 100 microg T4 orally per day<ref name="pmid17299073">{{cite journal| author=Razvi S, Ingoe L, Keeka G, Oates C, McMillan C, Weaver JU| title=The beneficial effect of L-thyroxine on cardiovascular risk factors, endothelial function, and quality of life in subclinical hypothyroidism: randomized, crossover trial. | journal=J Clin Endocrinol Metab | year= 2007 | volume= 92 | issue= 5 | pages= 1715-23 | pmid=17299073 | doi=10.1210/jc.2006-1869 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=17299073  }} </ref> and negative using 25 microg T4 orally per day<ref name="pmid20501682">{{cite journal| author=Parle J, Roberts L, Wilson S, Pattison H, Roalfe A, Haque MS et al.| title=A randomized controlled trial of the effect of thyroxine replacement on cognitive function in community-living elderly subjects with subclinical hypothyroidism: the Birmingham Elderly Thyroid study. | journal=J Clin Endocrinol Metab | year= 2010 | volume= 95 | issue= 8 | pages= 3623-32 | pmid=20501682 | doi=10.1210/jc.2009-2571 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20501682  }} </ref>.
 
Subsequent observational studies have<ref name="pmid22529180">{{cite journal| author=Razvi S, Weaver JU, Butler TJ, Pearce SH| title=Levothyroxine Treatment of Subclinical Hypothyroidism, Fatal and Nonfatal Cardiovascular Events, and Mortality. | journal=Arch Intern Med | year= 2012 | volume=  | issue=  | pages=  | pmid=22529180 | doi=10.1001/archinternmed.2012.1159 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22529180  }} </ref> and have not<ref name="pmid20150579">{{cite journal| author=Razvi S, Weaver JU, Vanderpump MP, Pearce SH| title=The incidence of ischemic heart disease and mortality in people with subclinical hypothyroidism: reanalysis of the Whickham Survey cohort. | journal=J Clin Endocrinol Metab | year= 2010 | volume= 95 | issue= 4 | pages= 1734-40 | pmid=20150579 | doi=10.1210/jc.2009-1749 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20150579  }} </ref> shown a relationship between untreated subclinical hypothyroidism and ischemic heart disease.
 
[[Clinical practice guideline]]s guide management.<ref name="pmid22967432">{{cite journal| author=Garber JR, Cobin RH, Gharib H, Hennessey JV, Klein I, Mechanick JI et al.| title=Clinical Practice Guidelines for Hypothyroidism in Adults: Co-sponsored by American Association of Clinical Endocrinologists and the American Thyroid Association. | journal=Endocr Pract | year= 2012 | volume=  | issue=  | pages= 1-207 | pmid=22967432 | doi=10.4158/EP12280.GL | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22967432  }} </ref>


Prior consensus statements conflict with some recommending<ref name="pmid15687817">{{cite journal| author=Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA, McDermott MT et al.| title=Consensus Statement #1: Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and The Endocrine Society. | journal=Thyroid | year= 2005 | volume= 15 | issue= 1 | pages= 24-8; response 32-3 | pmid=15687817 | doi=10.1089/thy.2005.15.24 | pmc= | url= }} </ref><ref name="pmid16033723">{{cite journal| author=Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA, McDermott MT et al.| title=Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and the Endocrine Society. | journal=Endocr Pract | year= 2004 | volume= 10 | issue= 6 | pages= 497-501 | pmid=16033723 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16033723  }} </ref><ref name="pmid15643019">{{cite journal| author=Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA, McDermott MT| title=Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and the Endocrine Society. | journal=J Clin Endocrinol Metab | year= 2005 | volume= 90 | issue= 1 | pages= 581-5; discussion 586-7 | pmid=15643019 | doi=10.1210/jc.2004-1231 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15643019  }} </ref> and others not<ref name="pmid14722150">{{cite journal| author=Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH et al.| title=Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. | journal=JAMA | year= 2004 | volume= 291 | issue= 2 | pages= 228-38 | pmid=14722150 | doi=10.1001/jama.291.2.228 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14722150  }} </ref> recommending treatment.<ref name="pmid15643021">{{cite journal| author=Ringel MD, Mazzaferri EL| title=Subclinical thyroid dysfunction--can there be a consensus about the consensus? | journal=J Clin Endocrinol Metab | year= 2005 | volume= 90 | issue= 1 | pages= 588-90 | pmid=15643021 | doi=10.1210/jc.2004-2173 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15643021  }} </ref>
Prior consensus statements conflict with some recommending<ref name="pmid15687817">{{cite journal| author=Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA, McDermott MT et al.| title=Consensus Statement #1: Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and The Endocrine Society. | journal=Thyroid | year= 2005 | volume= 15 | issue= 1 | pages= 24-8; response 32-3 | pmid=15687817 | doi=10.1089/thy.2005.15.24 | pmc= | url= }} </ref><ref name="pmid16033723">{{cite journal| author=Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA, McDermott MT et al.| title=Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and the Endocrine Society. | journal=Endocr Pract | year= 2004 | volume= 10 | issue= 6 | pages= 497-501 | pmid=16033723 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16033723  }} </ref><ref name="pmid15643019">{{cite journal| author=Gharib H, Tuttle RM, Baskin HJ, Fish LH, Singer PA, McDermott MT| title=Subclinical thyroid dysfunction: a joint statement on management from the American Association of Clinical Endocrinologists, the American Thyroid Association, and the Endocrine Society. | journal=J Clin Endocrinol Metab | year= 2005 | volume= 90 | issue= 1 | pages= 581-5; discussion 586-7 | pmid=15643019 | doi=10.1210/jc.2004-1231 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15643019  }} </ref> and others not<ref name="pmid14722150">{{cite journal| author=Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH et al.| title=Subclinical thyroid disease: scientific review and guidelines for diagnosis and management. | journal=JAMA | year= 2004 | volume= 291 | issue= 2 | pages= 228-38 | pmid=14722150 | doi=10.1001/jama.291.2.228 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14722150  }} </ref> recommending treatment.<ref name="pmid15643021">{{cite journal| author=Ringel MD, Mazzaferri EL| title=Subclinical thyroid dysfunction--can there be a consensus about the consensus? | journal=J Clin Endocrinol Metab | year= 2005 | volume= 90 | issue= 1 | pages= 588-90 | pmid=15643021 | doi=10.1210/jc.2004-2173 | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=15643021  }} </ref>


==Screening==
==Screening==
The [[US Preventive Services Task Force]] states:<ref name="pmid14734337">{{cite journal| author=Helfand M, U.S. Preventive Services Task Force| title=Screening for subclinical thyroid dysfunction in nonpregnant adults: a summary of the evidence for the U.S. Preventive Services Task Force. | journal=Ann Intern Med | year= 2004 | volume= 140 | issue= 2 | pages= 128-41 | pmid=14734337 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14734337  }} </ref>
The [[U.S. Preventive Services Task Force]] states:<ref name="pmid14734337">{{cite journal| author=Helfand M, U.S. Preventive Services Task Force| title=Screening for subclinical thyroid dysfunction in nonpregnant adults: a summary of the evidence for the U.S. Preventive Services Task Force. | journal=Ann Intern Med | year= 2004 | volume= 140 | issue= 2 | pages= 128-41 | pmid=14734337 | doi= | pmc= | url=http://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=14734337  }} </ref>


:"t is uncertain whether treatment will improve quality of life in  otherwise healthy patients who have abnormal TSH levels and normal free thyroxine levels."
:"t is uncertain whether treatment will improve quality of life in  otherwise healthy patients who have abnormal TSH levels and normal free thyroxine levels."
Line 52: Line 58:


==References==
==References==
<small>
<references/>
<references/>
</small>

Latest revision as of 09:18, 22 October 2024

This article is developing and not approved.
Main Article
Discussion
Related Articles  [?]
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External Links  [?]
Citable Version  [?]
 
This editable Main Article is under development and subject to a disclaimer.

In medicine, subclinical hypothyroidism is an elevated thyrotropin (a.k.a. thyroid stimulating hormone, or TSH) concentration can maintain a normal or near normal thyroxine (T4) concentration.[1][2]

Prognosis

"Subclinical hypothyroidism is associated with an increased risk of congenital heart disease (CHD) events and CHD mortality in those with higher TSH levels, particularly in those with a TSH concentration of 10 mIU/L or greater" according to a individual patient data meta-analysis. [3]

Thyrotropin level

Evolution of thyrotropin values over 5 years.[4]
  Follow-up TSH value
TSH > 10 TSH < 10
TSH > 10 35% 64%
TSH 5.5 - 10 3% 97%

The thyrotropin level helps predict progression to overt hypothyroidism.[4]

Antithyroid peroxidase antibodies

Antithyroid peroxidase (also called antithyroid microsomal) antibodies my help predict progression to overt hypothyroidism.[5][6][7]

Diagnostic accuracy for predicting over hypothyroidism has been reported.

Diez et al found that among patients with TSH > 5, antibodies > 20 U/ml were significant predictors of hypothyrodism after 3.5 years of follow-up in which 26% developed overt hypothyroidism, but not after controlling for initial thyrotropin level.[7]

  • Sensitivity 93%
  • Specificity 30%
  • Positive predictive value 32%
  • Negative predictive value 92%

Walsh et al found that among patients with TSH> 4, antibodies > 35 U/ml were significant predictors of hypothyrodism after 13 years of follow-up in which 31% developed overt hypothyroidism, but not after controlling for initial thyrotropin level.[5]

  • Sensitivity 84%
  • Specificity 30%
  • Positive predictive value 60%
  • Negative predictive value 60%

Treatment

"In current RCTs, levothyroxine replacement therapy for subclinical hypothyroidism did not result in improved survival or decreased cardiovascular morbidity" according to a meta-analysis by the Cochrane Collaboration. [8]

Subsequent randomized controlled trials have been positive using 100 microg T4 orally per day[9] and negative using 25 microg T4 orally per day[10].

Subsequent observational studies have[11] and have not[12] shown a relationship between untreated subclinical hypothyroidism and ischemic heart disease.

Clinical practice guidelines guide management.[13]

Prior consensus statements conflict with some recommending[14][15][16] and others not[1] recommending treatment.[17]

Screening

The U.S. Preventive Services Task Force states:[18]

"t is uncertain whether treatment will improve quality of life in otherwise healthy patients who have abnormal TSH levels and normal free thyroxine levels."

The Institute of Medicine recommends against screening.[19]

References

  1. 1.0 1.1 Surks MI, Ortiz E, Daniels GH, Sawin CT, Col NF, Cobin RH et al. (2004). "Subclinical thyroid disease: scientific review and guidelines for diagnosis and management.". JAMA 291 (2): 228-38. DOI:10.1001/jama.291.2.228. PMID 14722150. Research Blogging.
  2. Cooper DS, Biondi B (2012). "Subclinical thyroid disease.". Lancet 379 (9821): 1142-54. DOI:10.1016/S0140-6736(11)60276-6. PMID 22273398. Research Blogging.
  3. Rodondi N, den Elzen WP, Bauer DC, Cappola AR, Razvi S, Walsh JP et al. (2010). "Subclinical hypothyroidism and the risk of coronary heart disease and mortality.". JAMA 304 (12): 1365-74. DOI:10.1001/jama.2010.1361. PMID 20858880. Research Blogging. Review in: Evid Based Med. 2011 Feb;16(1):31-2
  4. 4.0 4.1 Meyerovitch J, Rotman-Pikielny P, Sherf M, Battat E, Levy Y, Surks MI (2007). "Serum thyrotropin measurements in the community: five-year follow-up in a large network of primary care physicians.". Arch Intern Med 167 (14): 1533-8. DOI:10.1001/archinte.167.14.1533. PMID 17646608. Research Blogging.
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