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{{WikiDoc CMG}}; {{AE}}
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! style="padding: 0 5px; font-size: 85%; background: #A8A8A8" align="center" |{{fontcolor|#2B3B44|Hypothyroidism Resident Survival Guide Microchapters}}
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align="left" |[[Hypothyroidism resident survival guide#Overview|Overview]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align="left" |[[Hypothyroidism resident survival guide#Causes|Causes]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align="left" |[[Hypothyroidism resident survival guide#Diagnosis|Diagnosis]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align="left" |[[Hypothyroidism resident survival guide#Treatment|Treatment]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align="left" |[[Hypothyroidism resident survival guide#Do's|Do's]]
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! style="font-size: 80%; padding: 0 5px; background: #DCDCDC" align="left" |[[Hypothyroidism resident survival guide#Don'ts|Don'ts]]
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{{WikiDoc CMG}}; {{AE}}{{Ayeesha}}
 
{{SK}} Approach to hypothyroidism, Hypothyroidism work-up, Hypothyroidism management
==Overview==
==Overview==
[[Hypothyroidism]] refers to a clinical state where there is reduced production or action of the [[thyroid hormone]].
[[Hypothyroidism]] is a [[clinical]] state where there is a reduced production or action of [[thyroid  hormones]] - [[Thyroxine]] ([[T4]]) and [[Triiodothyronine]] ([[T3]]). It is classified based on the location of [[pathology]] into [[primary hypothyroidism]], [[secondary hypothyroidism]] and [[tertiary hypothyroidism]]. The most common cause worldwide is [[Iodine]] deficiency. In [[iodine]] sufficient areas the most common cause is [[autoimmune thyroiditis]]. Risk factors for the development of [[hypothyroidism]] include female sex, [[iodine]] deficiency, [[selenium]] deficiency, presence of other [[autoimmune]] conditions. [[Clinical]] presentation depends on the degree and rapidity of [[hormone]] depletion. Patients can be [[asymptomatic]] or present with  symptoms like [[cold intolerance]], [[fatigue]], [[weight gain]], [[constipation]], [[depression]], [[neck mass]]. The [[diagnosis]] of [[hypothyroidism]] is made with the help of [[biochemical]] tests measuring [[TSH]] and [[Thyroxine]] ([[FT4]]) levels. [[Treatment]] of this condition is with [[Levothyroxine]] supplementation. <ref name="pmid29569622">{{cite journal| author=Taylor PN, Albrecht D, Scholz A, Gutierrez-Buey G, Lazarus JH, Dayan CM | display-authors=etal| title=Global epidemiology of hyperthyroidism and hypothyroidism. | journal=Nat Rev Endocrinol | year= 2018 | volume= 14 | issue= 5 | pages= 301-316 | pmid=29569622 | doi=10.1038/nrendo.2018.18 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29569622  }} </ref>


==Causes==
==Causes==
<br />[[Hypothyroidism]] can be classified based on the location of the [[pathology]] or based on [[etiology]] as shown in the table below.<ref name="pmid29044016">{{cite journal| author=Rizzo LFL, Mana DL, Serra HA| title=Drug-induced hypothyroidism. | journal=Medicina (B Aires) | year= 2017 | volume= 77 | issue= 5 | pages= 394-404 | pmid=29044016 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29044016  }} </ref> <ref name="pmid29380231">{{cite journal| author=Falhammar H, Juhlin CC, Barner C, Catrina SB, Karefylakis C, Calissendorff J| title=Riedel's thyroiditis: clinical presentation, treatment and outcomes. | journal=Endocrine | year= 2018 | volume= 60 | issue= 1 | pages= 185-192 | pmid=29380231 | doi=10.1007/s12020-018-1526-3 | pmc=5845586 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29380231  }} </ref> <ref name="pmid21966662">{{cite journal| author=Gupta V, Lee M| title=Central hypothyroidism. | journal=Indian J Endocrinol Metab | year= 2011 | volume= 15 | issue= Suppl 2 | pages= S99-S106 | pmid=21966662 | doi=10.4103/2230-8210.83337 | pmc=3169862 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21966662  }} </ref> <ref name="pmid26085833">{{cite journal| author=Vural Ç, Paksoy N, Gök ND, Yazal K| title=Subacute granulomatous (De Quervain's) thyroiditis: Fine-needle aspiration cytology and ultrasonographic characteristics of 21 cases. | journal=Cytojournal | year= 2015 | volume= 12 | issue=  | pages= 9 | pmid=26085833 | doi=10.4103/1742-6413.157479 | pmc=4453108 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26085833  }} </ref> <ref name="pmid16424561">{{cite journal| author=Kumar PG, Anand SS, Sood V, Kotwal N| title=Thyroid dyshormonogenesis. | journal=Indian Pediatr | year= 2005 | volume= 42 | issue= 12 | pages= 1233-5 | pmid=16424561 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16424561  }} </ref>
<br />[[Hypothyroidism]] can be classified based on the location of the [[pathology]] or based on [[etiology]] as shown in the table below.<ref name="pmid29044016">{{cite journal| author=Rizzo LFL, Mana DL, Serra HA| title=Drug-induced hypothyroidism. | journal=Medicina (B Aires) | year= 2017 | volume= 77 | issue= 5 | pages= 394-404 | pmid=29044016 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29044016  }} </ref><ref name="pmid29380231">{{cite journal| author=Falhammar H, Juhlin CC, Barner C, Catrina SB, Karefylakis C, Calissendorff J| title=Riedel's thyroiditis: clinical presentation, treatment and outcomes. | journal=Endocrine | year= 2018 | volume= 60 | issue= 1 | pages= 185-192 | pmid=29380231 | doi=10.1007/s12020-018-1526-3 | pmc=5845586 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=29380231  }} </ref><ref name="pmid21966662">{{cite journal| author=Gupta V, Lee M| title=Central hypothyroidism. | journal=Indian J Endocrinol Metab | year= 2011 | volume= 15 | issue= Suppl 2 | pages= S99-S106 | pmid=21966662 | doi=10.4103/2230-8210.83337 | pmc=3169862 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=21966662  }} </ref><ref name="pmid26085833">{{cite journal| author=Vural Ç, Paksoy N, Gök ND, Yazal K| title=Subacute granulomatous (De Quervain's) thyroiditis: Fine-needle aspiration cytology and ultrasonographic characteristics of 21 cases. | journal=Cytojournal | year= 2015 | volume= 12 | issue=  | pages= 9 | pmid=26085833 | doi=10.4103/1742-6413.157479 | pmc=4453108 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26085833  }} </ref><ref name="pmid16424561">{{cite journal| author=Kumar PG, Anand SS, Sood V, Kotwal N| title=Thyroid dyshormonogenesis. | journal=Indian Pediatr | year= 2005 | volume= 42 | issue= 12 | pages= 1233-5 | pmid=16424561 | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=16424561  }} </ref>
 
===Life Threatening Causes===
 
*[[Myxedema coma]]
 
===Common Causes===
 
*'''[[Primary hypothyroidism]]:'''
**[[Iodine deficiency]],
**[[Autoimmune thyroiditis]].
*'''[[Central hypothyroidism]]:'''
**[[Pituitary macroadenoma]],
**[[Iatrogenic]] (Pituitary surgery, radiation).
*'''[[Congenital hypothyroidism]]:'''
**[[Iodine deficiency]],
**[[Thyroid dysgenesis]].
 
{| class="wikitable"
{| class="wikitable"
|+
|+
! colspan="14" |Causes of [[hypothyroidism]]
! colspan="14" style="background: #4479BA; color: #FFFFFF " |Causes of [[hypothyroidism]]
|-
|-
! colspan="5" |'''[[Primary hypothyroidism]]'''
! colspan="5" style="background: #4479BA; color: #FFFFFF " |'''[[Primary hypothyroidism]]'''
! colspan="7" |[[Central hypothyroidism]]
! colspan="7" style="background: #4479BA; color: #FFFFFF " |[[Central hypothyroidism]]
( Secondary and Tertiary )
( Secondary and Tertiary )
! rowspan="2" |[[Congenital hypothyroidism]]
! rowspan="2" style="background: #4479BA; color: #FFFFFF " |[[Congenital hypothyroidism]]
|-
|-
!Auto immune
! style="background: #4479BA; color: #FFFFFF " |[[Autoimmune]]
!Drug induced
! style="background: #4479BA; color: #FFFFFF " |Drug induced
!Iatrogenic
! style="background: #4479BA; color: #FFFFFF " |[[Iatrogenic]]
!Transient
! style="background: #4479BA; color: #FFFFFF " |[[Transient Hypothyroidism]]
Hypothyroidism
! style="background: #4479BA; color: #FFFFFF " |[[Infiltrative disorders]]
!Infiltrative disorders
! style="background: #4479BA; color: #FFFFFF " |[[Genetic]] causes
!Genetic causes
! style="background: #4479BA; color: #FFFFFF " |[[Iatrogenic]]
!Iatrogenic
! style="background: #4479BA; color: #FFFFFF " |[[Tumors]]
!Tumors
! style="background: #4479BA; color: #FFFFFF " |[[Vascular]]
!Vascular
! style="background: #4479BA; color: #FFFFFF " |[[Infiltrative]]
!Infiltrative
! style="background: #4479BA; color: #FFFFFF " |[[Infectious]]
!Infectious
! style="background: #4479BA; color: #FFFFFF " |Miscellaneous
!Miscellaneous
|-
|-
|
|
* <big>[[Hashimotos thyroiditis]]</big>
*[[Hashimoto's thyroiditis]]
* <big>Atrophic thyroiditis</big>
*Atrophic [[thyroiditis]]
|
|
* [[Lithium]]
*[[Lithium]]
* Thionamides
*[[Thionamides]]
* [[Amiodarone]]
*[[Amiodarone]]
* [[Iodine containing contrast agents]]  
*[[Iodine containing contrast agents]]
* Interferon - alfa
*[[Interferon]] - alfa
* Tyrosine kinase inhibitor
*Tyrosine kinase inhibitor
|
|
* Subtotal or Total thyroidectomy
*[[Iodine deficiency]]
* Radioiodine therapy
*Subtotal or Total [[thyroidectomy]]
* External radiation of the neck
*[[Radioiodine]] therapy
* Iodine deficiency
*External [[radiation]] of the neck
|
|
* [[Subacute granulomatous thyroiditis]]
*[[Subacute granulomatous thyroiditis]]
* [[Postpartum thyroiditis]]
*[[Postpartum thyroiditis]]
* Painless (silent, lymphocytic) thyroiditis
*Painless (silent, lymphocytic) [[thyroiditis]]
|
|
* [[Amyloidosis]]
*[[Amyloidosis]]
* [[Sarcoidosis]]
*[[Sarcoidosis]]
* [[Hemochromatosis]]
*[[Hemochromatosis]]
* [[Scleroderma]]
*[[Scleroderma]]
* [[Cystinosis]]
*[[Cystinosis]]
* Reidel's thyroiditis( fibrous thyroiditis )
*Reidel's [[thyroiditis]]( fibrous [[thyroiditis]] )
|
|
* [[TRH]] deficiency
*[[TRH]] deficiency
* Isolated CeH
*Isolated CeH
* Inactive [[TSH]]
*Inactive [[TSH]]
* Inactive [[TRH]] receptor
*Inactive [[TRH]] receptor
|
|
* Post pituitary surgery
*Post [[pituitary]] surgery
* Post external radiation
*Post external [[radiation]]
* '''Drugs''':<br> [[Growth hormone]] therapy,<br> [[Glucocorticoids]],<br> Retinoid X Receptor(RXR)<br>agonists, <br>[[Salicylates]], <br>[[Dopamine]]
*'''Drugs''':<br> [[Growth hormone]] therapy,<br> [[Glucocorticoids]],<br> Retinoid X Receptor(RXR)<br>agonists, <br>[[Salicylates]], <br>[[Dopamine]]
|
|
* [[Pituitary macroadenoma]]
*[[Pituitary macroadenoma]]
* [[Craniopharyngioma]]
*[[Craniopharyngioma]]
* [[Meningioma]]
*[[Meningioma]]
* [[Glioma]]
*[[Glioma]]
* Rathke cleft cyst
*Rathke cleft cyst
* [[Metastatic]]
*[[Metastatic]]
|
|
* '''[[Hemorrhage]]''': [[Pituitary apoplexy]], [[Subarachnoid hemorrhage]]
*'''[[Hemorrhage]]''': [[Pituitary apoplexy]], [[Subarachnoid hemorrhage]]
* '''[[Ischemia]]''': [[Postpartum pituitary necrosis]]
*'''[[Ischemia]]''': [[Postpartum pituitary necrosis]]
* [[Aneurysm]]
*[[Aneurysm]]
|
|
* [[Hemochromatosis]]
*[[Hemochromatosis]]
* [[Histiocytosis]]
*[[Histiocytosis]]
* [[Sarcoidosis]]
*[[Sarcoidosis]]
|
|
* [[Syphilis]]
*[[Syphilis]]
* [[Bacterial abscess]]
*[[Bacterial abscess]]
* [[Tuberculosis]]
*[[Tuberculosis]]
* [[Toxoplasmosis]]
*[[Toxoplasmosis]]
|
|
* '''Transient''': overreplacement of T4 in primary hypothyroidism, Sick euthyroid state
*'''[[Transient]]''': overreplacement of [[T4]] in [[primary hypothyroidism]], [[Sick euthyroid state]]
* '''Trauma''': head injury  
*'''Trauma''': head injury
|
|
* [[Thyroid dysgenesis]]
*[[Iodine deficiency]]
* [[Thyroid agenesis]]
*[[Thyroid dysgenesis]]
* [[Thyroid dyshormonogenesis]]
*[[Thyroid agenesis]]
*[[Thyroid dyshormonogenesis]]
|}
|}
<br />
<br />


==Diagnosis==
==Diagnosis==
Shown below is an algorithm summarizing the diagnosis of <nowiki>[[hypothyroidism]]</nowiki> <ref name="pmid10847249">{{cite journal| author=Ladenson PW, Singer PA, Ain KB, Bagchi N, Bigos ST, Levy EG | display-authors=etal| title=American Thyroid Association guidelines for detection of thyroid dysfunction. | journal=Arch Intern Med | year= 2000 | volume= 160 | issue= 11 | pages= 1573-5 | pmid=10847249 | doi=10.1001/archinte.160.11.1573 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10847249  }} </ref> <ref name="pmid 20097710 ">{{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=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20097710  }} </ref> <ref name="pmid 32349628  ">{{cite journal| author=Fitzgerald SP, Bean NG, Falhammar H, Tuke J| title=Clinical Parameters Are More Likely to Be Associated with Thyroid Hormone Levels than with Thyrotropin Levels: A Systematic Review and Meta-analysis. | journal=Thyroid | year= 2020 | volume=  | issue=  | pages=  | pmid= 32349628   | doi=10.1089/thy.2019.0535 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=32349628  }} </ref> <ref name="pmid28657873">{{cite journal| author=Peeters RP| title=Subclinical Hypothyroidism. | journal=N Engl J Med | year= 2017 | volume= 376 | issue= 26 | pages= 2556-2565 | pmid=28657873 | doi=10.1056/NEJMcp1611144 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28657873  }} </ref> <ref name="pmid30374425">{{cite journal| author=Persani L, Brabant G, Dattani M, Bonomi M, Feldt-Rasmussen U, Fliers E | display-authors=etal| title=2018 European Thyroid Association (ETA) Guidelines on the Diagnosis and Management of Central Hypothyroidism. | journal=Eur Thyroid J | year= 2018 | volume= 7 | issue= 5 | pages= 225-237 | pmid=30374425 | doi=10.1159/000491388 | pmc=6198777 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30374425 }} </ref>
Shown below is an algorithm summarizing the diagnosis of [[hypothyroidism]]: <ref name="pmid10847249">{{cite journal| author=Ladenson PW, Singer PA, Ain KB, Bagchi N, Bigos ST, Levy EG | display-authors=etal| title=American Thyroid Association guidelines for detection of thyroid dysfunction. | journal=Arch Intern Med | year= 2000 | volume= 160 | issue= 11 | pages= 1573-5 | pmid=10847249 | doi=10.1001/archinte.160.11.1573 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10847249  }} </ref><ref name="pmid 20097710">{{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=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=20097710  }} </ref><ref name="pmid 32349628">{{cite journal| author=Fitzgerald SP, Bean NG, Falhammar H, Tuke J| title=Clinical Parameters Are More Likely to Be Associated with Thyroid Hormone Levels than with Thyrotropin Levels: A Systematic Review and Meta-analysis. | journal=Thyroid | year= 2020 | volume=  | issue=  | pages=  | pmid= 32349628   | doi=10.1089/thy.2019.0535 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=32349628  }} </ref><ref name="pmid28657873">{{cite journal| author=Peeters RP| title=Subclinical Hypothyroidism. | journal=N Engl J Med | year= 2017 | volume= 376 | issue= 26 | pages= 2556-2565 | pmid=28657873 | doi=10.1056/NEJMcp1611144 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=28657873  }} </ref><ref name="pmid30374425">{{cite journal| author=Persani L, Brabant G, Dattani M, Bonomi M, Feldt-Rasmussen U, Fliers E | display-authors=etal| title=2018 European Thyroid Association (ETA) Guidelines on the Diagnosis and Management of Central Hypothyroidism. | journal=Eur Thyroid J | year= 2018 | volume= 7 | issue= 5 | pages= 225-237 | pmid=30374425 | doi=10.1159/000491388 | pmc=6198777 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=30374425}} </ref> <br>
 


{{familytree/start}}
{{familytree/start}}
{{familytree | | | | | | | | | | | | | | | | | | | | A01 | | | | | | | | | |A01=Signs and Symptoms of hypothyroidism are present.}}
{{familytree | | | | | | | | | | | | | | | | | | | | A01 | | | | | | | | | |A01=[[Signs]] and [[Symptoms]] of [[hypothyroidism]] are present.}}
{{familytree | | | | | | | | | | | | | | | | | | | | |!| | | | | | | | | | | | }}
{{familytree | | | | | | | | | | | | | | | | | | | | |!| | | | | | | | | | | |}}
{{familytree | | | | | | | | | | | | | | | | | | | | B01 | | | | | | | | | | |B01=[[TSH]], free T4 ([[FT4]])}}
{{familytree | | | | | | | | | | | | | | | | | | | | B01 | | | | | | | | | | |B01=[[TSH]], free T4 ([[FT4]])}}
{{familytree | | | | | | | | | | | | | | | | | | | | |!| | | | | | | | | | | | | | | | |}}
{{familytree | | | | | | | | | | | | | | | | | | | | |!| | | | | | | | | | | | | | | | |}}
{{familytree | | | | | | | | | |,|-|-|-|-|-|-|-|-|-|-|+|-|-|-|-|-|-|-|-|-|-|-|.| |}}
{{familytree | | | | | | | | | |,|-|-|-|-|-|-|-|-|-|-|+|-|-|-|-|-|-|-|-|-|-|-|.| |}}
{{familytree | | | | | | | | | |!| | | | | | | | | | |!| | | | | | | | | | | |!| |}}
{{familytree | | | | | | | | | |!| | | | | | | | | | |!| | | | | | | | | | | |!| |}}
{{familytree | | | | | | | | | C01 | | | | | | | | | C02 | | | | | | | | | | C03 ||C01=[[TSH]] >5.5mU/L|C02=[[TSH]] 0.5-5mU/L|C03=[[TSH]]<0.5mU/L}}
{{familytree | | | | | | | | | C01 | | | | | | | | | C02 | | | | | | | | | | C03 |C01=[[TSH]] >5.5mU/L|C02=[[TSH]] 0.5-5mU/L|C03=[[TSH]]<0.5mU/L}}
{{familytree | | | | |,|-|-|-|-|+|-|-|-|-|-|.| | | | |!| | | | | | | | | | | |!| |}}
{{familytree | | | | |,|-|-|-|-|+|-|-|-|-|-|.| | | | |!| | | | | | | | | | | |!| |}}
{{familytree | | | | |!| | | | |!| | | | | |!| | | | |!| | | | | | | | | | | |!| |}}
{{familytree | | | | |!| | | | |!| | | | | |!| | | | |!| | | | | | | | | | | |!| |}}
{{familytree | | | | D01 | | | D02 | | | | D03 | | | D04 | | | | | | | | | | D05 ||D01=[[FT4]] Low|D02=[[FT4]] Normal|D03=[[FT4]] Elevated|D04=[[FT4]] Low|D05=[[FT4]] Low}}
{{familytree | | | | D01 | | | D02 | | | | D03 | | | D04 | | | | | | | | | | D05 |D01=[[FT4]] Low|D02=[[FT4]] Normal|D03=[[FT4]] Elevated|D04=[[FT4]] Low|D05=[[FT4]] Low}}
{{familytree | | | | |!| | | | |!| | | | | |!| | | | |!| | | | | | | | | | | |!| | | | |}}
{{familytree | | | | |!| | | | |!| | | | | |!| | | | |!| | | | | | | | | | | |!| | | | |}}
{{familytree | | | | E01 | | | E02 | | | | E03 | | | E04 | | | | | | | | | | E05 ||E01=TPOAb <br> ([[Thyroid peroxidase]] antibody)|E02=Subclinical hypothyroidism|E03= '''1.''' [[T4]] to [[T3]] conversion defect<br> (5' deiodinase deficiency, amiodarone use),<br> '''2.''' Thyroid hormone resistance | E04= '''1.''' Central hypothyroidism, <br> '''2.''' T3 replacement therapy | E05= '''1.''' Following excess levothyroxine withdrawal,<br> '''2.''' "Post hyperthyroid" hypothyroidism <br> ( I131 or surgery),<br> '''3.''' [[T3]] replacement therapy, <br> '''4.'''Central hypothyroidism}}
{{familytree | | | | E01 | | | E02 | | | | E03 | | | E04 | | | | | | | | | | E05 |E01=[[TPOAb]] <br> ([[Thyroid peroxidase]] [[antibody]])|E02=Subclinical [[hypothyroidism]]|E03= '''1.''' [[T4]] to [[T3]] conversion defect<br> (5' deiodinase deficiency, [[amiodarone]] use),<br> '''2.''' [[Thyroid hormone]] resistance | E04= '''1.''' Central [[hypothyroidism]], <br> '''2.''' [[T3]] replacement therapy | E05= '''1.''' Following excess [[levothyroxine]] withdrawal,<br> '''2.''' "Post hyperthyroid" [[hypothyroidism]] <br> ( I131 or surgery),<br> '''3.''' [[T3]] replacement therapy, <br> '''4.'''Central [[hypothyroidism]]}}
{{familytree | | |,|-|^|-|.| | | | | | | | | | | | | |`|-|-|-|-|-|v|-|-|-|-|-|'|}}}}
{{familytree | | |,|-|^|-|.| | | | | | | | | | | | | |`|-|-|-|-|-|v|-|-|-|-|-|'|}}
{{familytree | | |!| | | |!| | | | | | | | | | | | | | | | | | | |!| | | | | | |}}}}
{{familytree | | |!| | | |!| | | | | | | | | | | | | | | | | | | |!| | | | | | |}}
{{familytree | | F01 | | F02 | | | | | | | | | | | | | | | | | | F03 | | | | | | |F01=Positive|F02=Negative|F03= Central hypothyroidism}}
{{familytree | | F01 | | F02 | | | | | | | | | | | | | | | | | | F03 | | | | | | |F01=Positive|F02=Negative|F03= Central [[hypothyroidism]]}}
{{familytree | | |!| | | |!| | | | | | | | | | | | | | | | | | | |!| | | | | | | |}}}}
{{familytree | | |!| | | |!| | | | | | | | | | | | | | | | | | | |!| | | | | | | |}}
{{familytree | | G01 | | G02 | | | | | | | | | | | | | | | | | | G03 | | | | | | ||G01=Autoimmune thyroid disease <br> (Hashimotos disease)|G02= '''1.''' [[Euthyroid sick syndrome]] <br> '''2.''' External radiation <br> '''3.''' Drug induced <br> '''4.''' Iodine deficiency <br> '''5.''' [[Congenital hypothyroidism]] <br> '''6.''' Seronegative autoimmune thyroid disease| G03= Brain MRI }}
{{familytree | | G01 | | G02 | | | | | | | | | | | | | | | | | | G03 | | | | | | |G01=[[Autoimmune thyroid disease]] <br> [[(Hashimotos disease)]]|G02= '''1.''' [[Euthyroid sick syndrome]] <br> '''2.''' External [[radiation]] <br> '''3.''' Drug induced <br> '''4.''' [[Iodine deficiency]] <br> '''5.''' [[Congenital hypothyroidism]] <br> '''6.''' Seronegative [[autoimmune thyroid disease]]| G03= Brain [[MRI]] }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | |,|-|^|-|.| | | | }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | |,|-|^|-|.| | | | }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | H01 | | H02 | | | | ||H01= Abnormal| H02= Normal }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | H01 | | H02 | | | | |H01= Abnormal| H02= Normal}}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | |!| | | |!| | | | }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | |!| | | |!| | | | }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | I01 | | I02 | | | | ||I01= [[Pituitary]] or [[Hypothlamus]] lesion | I02= Congenital [[TRH]], [[TSH]] deficiency, <br> Infiltrative diseases }}
{{familytree | | | | | | | | | | | | | | | | | | | | | | | | I01 | | I02 | | | | |I01= [[Pituitary]] or [[Hypothlamus]] lesion | I02= [[Congenital]] [[TRH]], [[TSH]] deficiency, <br> Infiltrative [[diseases]]}}
{{familytree/end}}
{{familytree/end}}


==Treatment==
==Treatment==
Shown below is an algorithm summarizing the treatment of [[Primary hypothyroidism]]. <ref name="pmid26010808">{{cite journal| author=Okosieme O, Gilbert J, Abraham P, Boelaert K, Dayan C, Gurnell M | display-authors=etal| title=Management of primary hypothyroidism: statement by the British Thyroid Association Executive Committee. | journal=Clin Endocrinol (Oxf) | year= 2016 | volume= 84 | issue= 6 | pages= 799-808 | pmid=26010808 | doi=10.1111/cen.12824 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26010808  }} </ref> <ref name="pmid22291465">{{cite journal| author=Chakera AJ, Pearce SH, Vaidya B| title=Treatment for primary hypothyroidism: current approaches and future possibilities. | journal=Drug Des Devel Ther | year= 2012 | volume= 6 | issue=  | pages= 1-11 | pmid=22291465 | doi=10.2147/DDDT.S12894 | pmc=3267517 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22291465  }} </ref>
Shown below is an algorithm summarizing the treatment of [[Primary hypothyroidism]]. <ref name="pmid26010808">{{cite journal| author=Okosieme O, Gilbert J, Abraham P, Boelaert K, Dayan C, Gurnell M | display-authors=etal| title=Management of primary hypothyroidism: statement by the British Thyroid Association Executive Committee. | journal=Clin Endocrinol (Oxf) | year= 2016 | volume= 84 | issue= 6 | pages= 799-808 | pmid=26010808 | doi=10.1111/cen.12824 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=26010808  }} </ref><ref name="pmid22291465">{{cite journal| author=Chakera AJ, Pearce SH, Vaidya B| title=Treatment for primary hypothyroidism: current approaches and future possibilities. | journal=Drug Des Devel Ther | year= 2012 | volume= 6 | issue=  | pages= 1-11 | pmid=22291465 | doi=10.2147/DDDT.S12894 | pmc=3267517 | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22291465  }} </ref>


{{familytree/start |summary=Sample 1}}
{{familytree/start |summary=Sample 1}}
Line 129: Line 165:
{{familytree | | | | | | | | | | | B01 | | | | | | | | | B02 | | | | | | | | | ||B01= [[TSH]] > 5.5mU/L, <br> [[FT4]] Low|B02= [[TSH]] = 5.5 - 10 mU/L, <br> [[FT4]] Normal}}
{{familytree | | | | | | | | | | | B01 | | | | | | | | | B02 | | | | | | | | | ||B01= [[TSH]] > 5.5mU/L, <br> [[FT4]] Low|B02= [[TSH]] = 5.5 - 10 mU/L, <br> [[FT4]] Normal}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | |!| | | | | | | | |}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | |!| | | | | | | | |}}
{{familytree | | | | | | | | | | | C01 | | | | | | | | | C02 | | | | | | | | |C01= Start [[Levothyroxine]] | C02= Symptoms of [[hypothyroidism]]}}
{{familytree | | | | | | | | | | | C01 | | | | | | | | | C02 | | | | | | | | |C01= Start [[Levothyroxine]] | C02= [[Symptoms]] of [[hypothyroidism]]}}
{{familytree | | | | | | | | | | | |!| | | | | |,|-|-|-|-|^|-|-|-|-|.| | | | | | |}}
{{familytree | | | | | | | | | | | |!| | | | | |,|-|-|-|-|^|-|-|-|-|.| | | | | | |}}
{{familytree | | | | | | | | | | | D01 | | | | D02 | | | | | | | | D03 | | | | | | |D01= Measure [[TSH]] after 4-6 weeks|D02= Present|D03= Absent}}
{{familytree | | | | | | | | | | | D01 | | | | D02 | | | | | | | | D03 | | | | | | |D01= Measure [[TSH]] after 4-6 weeks|D02= Present|D03= Absent}}
{{familytree | | | | | | | | | | | |!| | | | | |!| | | | | | | | | |!| | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | | | |!| | | | | |!| | | | | | | | | |!| | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | | | E01 | | | | E02 | | | |,|-|-|-| E03 | | | | | E01= Goal [[TSH]] = 0.4-4mU/L <br> Adjust [[levothyroxine]] dose if goal TSH not reached|E02= [[Levothyroxine]] trial for 3-6 months.|E03=TPoAB <br> ([[Thyroid Peroxidase]] Antibodies}}
{{familytree | | | | | | | | | | | E01 | | | | E02 | | | |,|-|-|-| E03 | | | | | E01= Goal [[TSH]] = 0.4-4mU/L <br> Adjust [[levothyroxine]] dose if goal [[TSH]] not reached|E02= [[Levothyroxine]] trial for 3-6 months.|E03=TPoAB <br> ([[Thyroid Peroxidase]]) [[Antibodies]]}}
{{familytree | | | | | | | | | | | | | | | | | |!| | | | |!| | |,|-|^|-|.| | | | | | |}}
{{familytree | | | | | | | | | | | | | | | | | |!| | | | |!| | |,|-|^|-|.| | | | | | |}}
{{familytree | | | | | | | | | | | | | | | | | F01 | | | |!| | F02 | | F03 | | | | | |F01=Symptoms of [[hypothyroidism]]|F02= Positive| F03= Negative}}
{{familytree | | | | | | | | | | | | | | | | | F01 | | | |!| | F02 | | F03 | | | | | |F01=[[Symptoms]] of [[hypothyroidism]]|F02= Positive| F03= Negative}}
{{familytree | | | | | | | | | | | | | | | |,|-|^|-|.| | |!| | |!| | | |!| |}}
{{familytree | | | | | | | | | | | | | | | |,|-|^|-|.| | |!| | |!| | | |!| |}}
{{familytree | | | | | | | | | | | | | | | G01 | | G02 |-|'| | G03 | | G04 | | | G01= Resolved| G02= Unresolved| G03= Follow up with annual [[TSH]]| G04 = Follow up with [[TSH]] every 3 years}}
{{familytree | | | | | | | | | | | | | | | G01 | | G02 |-|'| | G03 | | G04 | | | G01= Resolved| G02= Unresolved| G03= Follow up with annual [[TSH]]| G04 = Follow up with [[TSH]] every 3 years}}
Line 142: Line 178:
{{familytree/end}}
{{familytree/end}}


Shown below is an algorithm summarizing the treatment of [[Central hypothyroidism]]. <ref name="pmid22851492">{{cite journal| author=Persani L| title=Clinical review: Central hypothyroidism: pathogenic, diagnostic, and therapeutic challenges. | journal=J Clin Endocrinol Metab | year= 2012 | volume= 97 | issue= 9 | pages= 3068-78 | pmid=22851492 | doi=10.1210/jc.2012-1616 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22851492  }} </ref>
Shown below is an algorithm summarizing the treatment of Central [[hypothyroidism]]. <ref name="pmid22851492">{{cite journal| author=Persani L| title=Clinical review: Central hypothyroidism: pathogenic, diagnostic, and therapeutic challenges. | journal=J Clin Endocrinol Metab | year= 2012 | volume= 97 | issue= 9 | pages= 3068-78 | pmid=22851492 | doi=10.1210/jc.2012-1616 | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=22851492  }} </ref>




{{familytree/start |summary=Sample 1}}
{{familytree/start |summary=Sample 1}}
{{familytree | | | | | | | | | | | | | | | | | | A01 | | | | | |A01=Central hypothyroidism}}
{{familytree | | | | | | | | | | | | | | | | | | A01 | | | | | |A01=Central [[hypothyroidism]]}}
{{familytree | | | | | | | | | | | | | | | | | | |!| | | | | |}}
{{familytree | | | | | | | | | | | | | | | | | | |!| | | | | |}}
{{familytree | | | | | | | | | | | | | | | | | | B01 | | | | | |B01=[[TSH]]<0.5mU/L <br> 0r 0.5-5.5mu/L, [[FT4]] Low }}
{{familytree | | | | | | | | | | | | | | | | | | B01 | | | | | |B01=[[TSH]]<0.5mU/L <br> 0r 0.5-5.5mu/L, [[FT4]] Low }}
Line 154: Line 190:
{{familytree | | | | | | | | | | | D01 | | | | | | | | | | | | D02 | | | | | | | | | | |D01=No|D02=Yes}}
{{familytree | | | | | | | | | | | D01 | | | | | | | | | | | | D02 | | | | | | | | | | |D01=No|D02=Yes}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | | | | |!| | | | | | | | |}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | | | | |!| | | | | | | | |}}
{{familytree | | | | | | | | | | | E01 | | | | | | | | | | | | E02 | | | | | | | | | |E01= MRI Brain|E02= Give [[glucocorticoids]] for 1-2 weeks to prevent [[adrenal crisis]]}}
{{familytree | | | | | | | | | | | E01 | | | | | | | | | | | | E02 | | | | | | | | | |E01= [[MRI]] Brain|E02= Give [[glucocorticoids]] for 1-2 weeks to prevent [[adrenal crisis]]}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | | | | |!| | | | | | | | | |}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | | | | |!| | | | | | | | | |}}
{{familytree | | | | | | | | | | | F01 | | | | | | | | | | | | F02 | | | | | | | | | |F01= Tumor|F02=[[Levothyroxine]]}}
{{familytree | | | | | | | | | | | F01 | | | | | | | | | | | | F02 | | | | | | | | | |F01= [[Tumor]]|F02=[[Levothyroxine]]}}
{{familytree | | | | | | | | | |,|-|^|.| | | | | | | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | |,|-|^|.| | | | | | | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | G01 | | G02 | | | | | | | | | | | | | | | | | | | G01= Present|G02= Absent}}
{{familytree | | | | | | | | | G01 | | G02 | | | | | | | | | | | | | | | | | | | G01= Present|G02= Absent}}
{{familytree | | | | | | | | | |!| | | |!| | | | | | | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | |!| | | |!| | | | | | | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | H01 | | H02 | | | | | | | | | | | | | | | | | | | |H01= Consider Surgery|H02=[[Levothyroxine]]}}
{{familytree | | | | | | | | | H01 | | H02 | | | | | | | | | | | | | | | | | | | |H01= Consider [[Surgery]]|H02=[[Levothyroxine]]}}
{{familytree | | | | | | | | | |`|-|-|-|'| | | | | | | | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | |`|-|v|-|'| | | | | | | | | | | | | | | | | | | | | | | }}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | | | | | | | | | | | | |}}
{{familytree | | | | | | | | | | | |!| | | | | | | | | | | | | | | | | | | | | |}}
{{familytree | | | | | | | | | | | I01 | | | | | | | | | | | | | | | | | | | | | |I01= Reassess by measuring [[FT4]] <br> Goal [[FT4]] is <br>upper limit of normal}}
{{familytree | | | | | | | | | | | I01 | | | | | | | | | | | | | | | | | | | | | |I01= Reassess by measuring [[FT4]] <br> Goal [[FT4]] is <br>upper limit of normal}}
{{familytree/end}}
{{familytree/end}}


==Do's== {{cite web |url=https://journals.aace.com/doi/pdf/10.4158/EP12280.GL |title=journals.aace.com |format= |work= |accessdate=}}
==Do's==  


*When to take Levothyroxine: Morning 30-60 minutes before breakfast or 4 hours after last meal of the day. To be taken at the same time each day with water.
*When to take [[Levothyroxine]]: Morning 30-60 minutes before breakfast or 4 hours after last meal of the day. To be taken at the same time each day with water.<ref name="pmidhttps://doi.org/10.4158/EP12280.GL">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=https://doi.org/10.4158/EP12280.GL | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10  }} </ref>
*After initiation or change in dose of [[Levothyroxine]] in a patient [[diagnosed]] with [[hypothyroidism]], serum [[TSH]] measurements should be done after 4-8 weeks. Once the target [[TSH]] level is reached, the [[TSH]] level is to be repeated after 6 months, thereafter every 12 months.
*In patients who are started on drugs that alter the [[absorption]] or [[metabolism]] of [[Levothyroxine]], [[TSH]] should be measured within 4-8 weeks for dose adjustments.
*A patient may resume using the previously used full replacement dose of [[Levothyroxine]] after an interruption lasting less than 6 weeks if there was no cardiac event or [[weight loss]] in the interim.
*In a patient with subclinical [[hypothyroidism]] with [[TSH]] levels between the upper limit of normal and 10mIU/L treatment should be considered if -
**Patient is [[symptomatic]],
**Positive for [[TPOAb]],
**Evidence or association with risk factors for [[atherosclerotic cardiovascular disease]], [[heart failure]].
*In patients with central [[hypothyroidism]] associated with [[adrenal insufficiency]], [[glucocorticoid]] therapy should be given prior to starting [[Levothyroxine]].
*In patients with central [[hypothyroidism]] [[FT4]] levels guide therapy -  target level should be greater than mid-normal range value.


*After initiation or change in dose of Levothyroxine in a patient diagnosed with hypothyroidism, serum TSH measurements should be done after 4-8 weeks. Once the target TSH level is reached, the TSH level is to be repeated after 6 months, thereafter every 12 months.
==Don'ts== 


*In patients who are started on drugs that alter the absorption or metabolism of Levothyroxine, TSH should be measured within 4-8 weeks for dose adjustments.
*Serum [[FT3]] or Total [[T3]] levels – NOT to be used to [[diagnose]] [[hypothyroidism]].<ref name="pmidhttps://doi.org/10.4158/EP12280.GL">{{cite journal| author=Schmoldt A, Benthe HF, Haberland G| title=Digitoxin metabolism by rat liver microsomes. | journal=Biochem Pharmacol | year= 1975 | volume= 24 | issue= 17 | pages= 1639-41 | pmid=https://doi.org/10.4158/EP12280.GL | doi= | pmc= | url=https://www.ncbi.nlm.nih.gov/entrez/eutils/elink.fcgi?dbfrom=pubmed&tool=sumsearch.org/cite&retmode=ref&cmd=prlinks&id=10  }} </ref>
 
*In hospitalized patients, [[TSH]] measurements should not be done to assess thyroid function unless there is a high index of suspicion for thyroid disease.
*A patient may resume using the previously used full replacement dose of Levothyroxine after an interruption lasting less than 6 weeks if there was no cardiac event or weight loss in the interim.
*[[Cholesterol]] levels, muscle [[enzymes]], reflex relaxation time - cannot be used as diagnostic tools for [[hypothyroidism]].
 
*Thyroid replacement therapy NOT to be prescribed without [[biochemical]] evidence of [[hypothyroidism]].
*In a patient with subclinical hypothyroidism with TSH levels between upper limit of normal and 10mIU/L treatment should be considered if :
*Do not use thyroid replacement therapy for [[weight loss]] in [[obesity]] if the patient is [[euthyroid]].
**patient is symptomatic,
*[[Iodine]] supplementation/ [[iodine]]-rich foods should not be used in [[iodine]]-sufficient areas for [[hypothyroidism]].
**positive for TPOAb,
*Do not use [[Selenium]] for preventing or treating [[hypothyroidism]].
**evidence or association with risk factors for atherosclerotic cardiovascular disease, heart failure.
*Do not use desiccated [[thyroid hormone]] for the [[treatment]] of [[hypothyroidism]].
 
*In patients with central hypothyroidism associated with adrenal insufficiency, glucocorticoid therapy should be given prior to starting Levothyroxine
 
*In patients with central hypothyroidism FT4 levels guide therapy -  target level should be greater than mid-normal range value
 
==Don'ts==
* The content in this section is in bullet points.


==References==
==References==
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Latest revision as of 16:51, 25 January 2021

Hypothyroidism Resident Survival Guide Microchapters
Overview
Causes
Diagnosis
Treatment
Do's
Don'ts

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Ayeesha Kattubadi, M.B.B.S[2]

Synonyms and keywords: Approach to hypothyroidism, Hypothyroidism work-up, Hypothyroidism management

Overview

Hypothyroidism is a clinical state where there is a reduced production or action of thyroid hormones - Thyroxine (T4) and Triiodothyronine (T3). It is classified based on the location of pathology into primary hypothyroidism, secondary hypothyroidism and tertiary hypothyroidism. The most common cause worldwide is Iodine deficiency. In iodine sufficient areas the most common cause is autoimmune thyroiditis. Risk factors for the development of hypothyroidism include female sex, iodine deficiency, selenium deficiency, presence of other autoimmune conditions. Clinical presentation depends on the degree and rapidity of hormone depletion. Patients can be asymptomatic or present with symptoms like cold intolerance, fatigue, weight gain, constipation, depression, neck mass. The diagnosis of hypothyroidism is made with the help of biochemical tests measuring TSH and Thyroxine (FT4) levels. Treatment of this condition is with Levothyroxine supplementation. [1]

Causes


Hypothyroidism can be classified based on the location of the pathology or based on etiology as shown in the table below.[2][3][4][5][6]

Life Threatening Causes

Common Causes

Causes of hypothyroidism
Primary hypothyroidism Central hypothyroidism

( Secondary and Tertiary )

Congenital hypothyroidism
Autoimmune Drug induced Iatrogenic Transient Hypothyroidism Infiltrative disorders Genetic causes Iatrogenic Tumors Vascular Infiltrative Infectious Miscellaneous
  • TRH deficiency
  • Isolated CeH
  • Inactive TSH
  • Inactive TRH receptor


Diagnosis

Shown below is an algorithm summarizing the diagnosis of hypothyroidism: [7][8][9][10][11]


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Signs and Symptoms of hypothyroidism are present.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TSH, free T4 (FT4)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TSH >5.5mU/L
 
 
 
 
 
 
 
 
TSH 0.5-5mU/L
 
 
 
 
 
 
 
 
 
TSH<0.5mU/L
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
FT4 Low
 
 
FT4 Normal
 
 
 
FT4 Elevated
 
 
FT4 Low
 
 
 
 
 
 
 
 
 
FT4 Low
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TPOAb
(Thyroid peroxidase antibody)
 
 
Subclinical hypothyroidism
 
 
 
1. T4 to T3 conversion defect
(5' deiodinase deficiency, amiodarone use),
2. Thyroid hormone resistance
 
 
1. Central hypothyroidism,
2. T3 replacement therapy
 
 
 
 
 
 
 
 
 
1. Following excess levothyroxine withdrawal,
2. "Post hyperthyroid" hypothyroidism
( I131 or surgery),
3. T3 replacement therapy,
4.Central hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Positive
 
Negative
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Central hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Autoimmune thyroid disease
(Hashimotos disease)
 
1. Euthyroid sick syndrome
2. External radiation
3. Drug induced
4. Iodine deficiency
5. Congenital hypothyroidism
6. Seronegative autoimmune thyroid disease
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Brain MRI
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Abnormal
 
Normal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Pituitary or Hypothlamus lesion
 
Congenital TRH, TSH deficiency,
Infiltrative diseases
 
 
 
 

Treatment

Shown below is an algorithm summarizing the treatment of Primary hypothyroidism. [12][13]

 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Primary hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TSH > 5.5mU/L,
FT4 Low
 
 
 
 
 
 
 
 
TSH = 5.5 - 10 mU/L,
FT4 Normal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Start Levothyroxine
 
 
 
 
 
 
 
 
Symptoms of hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Measure TSH after 4-6 weeks
 
 
 
Present
 
 
 
 
 
 
 
Absent
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Goal TSH = 0.4-4mU/L
Adjust levothyroxine dose if goal TSH not reached
 
 
 
Levothyroxine trial for 3-6 months.
 
 
 
 
 
 
 
 
TPoAB
(Thyroid Peroxidase) Antibodies
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Symptoms of hypothyroidism
 
 
 
 
 
 
Positive
 
Negative
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Resolved
 
Unresolved
 
 
 
 
Follow up with annual TSH
 
Follow up with TSH every 3 years
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Lifelong levothyroxine therapy
 
 
 
 
 
 
 
 
 
 

Shown below is an algorithm summarizing the treatment of Central hypothyroidism. [14]


 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Central hypothyroidism
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
TSH<0.5mU/L
0r 0.5-5.5mu/L, FT4 Low
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Adrenal insufficiency
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
No
 
 
 
 
 
 
 
 
 
 
 
Yes
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
MRI Brain
 
 
 
 
 
 
 
 
 
 
 
Give glucocorticoids for 1-2 weeks to prevent adrenal crisis
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Tumor
 
 
 
 
 
 
 
 
 
 
 
Levothyroxine
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Present
 
Absent
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Consider Surgery
 
Levothyroxine
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
Reassess by measuring FT4
Goal FT4 is
upper limit of normal
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

Do's

Don'ts

References

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