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{{Euthyroid sick syndrome}}
{{Euthyroid sick syndrome}}


{{CMG}}; {{AE}}  
{{CMG}}; {{AE}}{{Akshun}}
==Overview==
==Overview==
*The exact pathogenesis of [disease name] is not fully understood.
[[Euthyroid]] sick syndrome is not a primary [[thyroid]] disorder but instead results from changes induced by the nonthyroidal illness. The cause of [[euthyroid]] sick syndrome is multifactorial. It is thought that [[euthyroid]] sick syndrome is the result of severe [[illness]] and [[inflammation]]. During these [[Stress (medicine)|stress]] conditions, [[hypermetabolism]] occur, that lead to  increased [[energy]] expenditure, [[hyperglycemia]], and [[muscle]] loss. It is speculated, that the body induces some degree of [[hypothyroidism]] by inhibiting deiodination of [[T4]] to [[T3]] by the [[enzyme]] 5’-monodeiodinase, in order to contain the [[hypermetabolism]]. This is an [[adaptive]] process by which the [[Human body|body]] prevents further [[muscle]] and [[calorie]] loss. [[Inflammation]] leads to increased production of [[cytokines]] that severely affects [[genes]] involved in the production and release of [[T4]] and [[T3]]. There is also [[downregulation]] of [[Thyrotropin-releasing hormone|TRH]] and [[Thyroid-stimulating hormone|TSH]] release from the [[hypothalamus]] and [[pituitary gland]] respectively. This downregulation may be signalled by a decrease in [[leptin]] caused by [[malnutrition]]. On [[gross pathology]], [[euthyroid]] sick syndrome, does not appear to be [[dysfunctional]]. On [[microscopic]] histopathological analysis, [[euthyroid]] sick syndrome presents with normal [[thyroid]] histology.
OR
 
*It is thought that [disease name] is the result of / is mediated by / is produced by / is caused by either [hypothesis 1], [hypothesis 2], or [hypothesis 3].
*[Pathogen name] is usually transmitted via the [transmission route] route to the human host.
*Following transmission/ingestion, the [pathogen] uses the [entry site] to invade the [cell name] cell.
*[Disease or malignancy name] arises from [cell name]s, which are [cell type] cells that are normally involved in [function of cells].
*The progression to [disease name] usually involves the [molecular pathway].
*The pathophysiology of [disease/malignancy] depends on the histological subtype.
==Pathophysiology==
==Pathophysiology==


===Pathogenesis===
===Pathogenesis===  
* [[T3]] ([[triiodothyronine]]) is the biologically active form of [[thyroid hormone]]. Normally most of the [[T3]] ([[triiodothyronine]]) is produced by peripheral deiodination of circulating [[T4]] ([[thyroxine]]) by the enzyme 5’-monodeiodinase (type I).  
* [[T3]] ([[triiodothyronine]]) is the biologically active form of [[thyroid hormone]]. Normally most of the [[T3]] ([[triiodothyronine]]) is produced by peripheral deiodination of circulating [[T4]] ([[thyroxine]]) by the enzyme 5’-monodeiodinase (type I).  
* In [[euthyroid]] sick syndrome there occurs [[inhibition]] of the [[enzyme]] 5’-monodeiodinase (type I) which leads to decrease conversion of [[T4]] to [[T3]] and an increase in [[reverse T3]] from decreased metabolism.  
* In [[euthyroid]] sick syndrome there occurs [[inhibition]] of the [[enzyme]] 5’-monodeiodinase (type I) which leads to decrease conversion of [[T4]] to [[T3]] and an increase in [[reverse T3]] from decreased metabolism.  
* [[Euthyroid]] sick syndrome is seen in [[conditions]] of [[starvation]] and [[critical illness]] such as [[sepsis]], [[surgery]], severe [[trauma]], [[burns]], [[metabolic disorders]], [[bone marrow transplantation]], and [[malignancy]].  
* [[Euthyroid]] sick syndrome is seen in [[conditions]] of [[starvation]] and [[critical illness]] such as [[sepsis]], [[surgery]], severe [[trauma]], [[burns]], [[metabolic disorders]], [[bone marrow transplantation]], and [[malignancy]].<ref name="pmid8940342">{{cite journal |vauthors=Boelen A, Maas MA, Lowik CW, Platvoet MC, Wiersinga WM |title=Induced illness in interleukin-6 (IL-6) knock-out mice: a causal role of IL-6 in the development of the low 3,5,3'-triiodothyronine syndrome |journal=Endocrinology |volume=137 |issue=12 |pages=5250–4 |year=1996 |pmid=8940342 |doi=10.1210/endo.137.12.8940342 |url=}}</ref><ref name="GRASBERGERGOLCHER2002">{{cite journal|last1=GRASBERGER|first1=Helmut|last2=GOLCHER|first2=Henriette M.B.|last3=FINGERHUT|first3=Anja|last4=JANSSEN|first4=Onno E.|title=Loop variants of the serpin thyroxine-binding globulin: implications for hormone release upon limited proteolysis|journal=Biochemical Journal|volume=365|issue=1|year=2002|pages=311–316|issn=0264-6021|doi=10.1042/bj20020014}}</ref><ref name="pmid10554534">{{cite journal |vauthors=Schilling JU, Zimmermann T, Albrecht S, Zwipp H, Saeger HD |title=[Low T3 syndrome in multiple trauma patients--a phenomenon or important pathogenetic factor?] |language=German |journal=Med. Klin. (Munich) |volume=94 Suppl 3 |issue= |pages=66–9 |year=1999 |pmid=10554534 |doi= |url=}}</ref><ref name="WongHershman1992">{{cite journal|last1=Wong|first1=Timothy K.|last2=Hershman|first2=Jerome M.|title=Changes in thyroid function in nonthyroid illness|journal=Trends in Endocrinology & Metabolism|volume=3|issue=1|year=1992|pages=8–12|issn=10432760|doi=10.1016/1043-2760(92)90085-F}}</ref><ref name="DocterKrenning1993">{{cite journal|last1=Docter|first1=R.|last2=Krenning|first2=E. P.|last3=Jong|first3=M.|last4=Hennemann|first4=G.|title=The sick euthyroid syndrome: changes in thyroid hormone serum parameters and hormone metabolism|journal=Clinical Endocrinology|volume=39|issue=5|year=1993|pages=499–518|issn=0300-0664|doi=10.1111/j.1365-2265.1993.tb02401.x}}</ref><ref name="BartalenaBogazzi1998">{{cite journal|last1=Bartalena|first1=L|last2=Bogazzi|first2=F|last3=Brogioni|first3=S|last4=Grasso|first4=L|last5=Martino|first5=E|title=Role of cytokines in the pathogenesis of the euthyroid sick syndrome|journal=European Journal of Endocrinology|volume=138|issue=6|year=1998|pages=603–614|issn=0804-4643|doi=10.1530/eje.0.1380603}}</ref>
** During these [[Stress (medicine)|stress]] conditions, there occurs [[hypermetabolism]], increased [[energy]] expenditure, [[hyperglycemia]], and [[muscle]] loss. It is speculated, that the body in order to contain this [[hypermetabolism]] induces some degree of [[hypothyroidism]] by inhibiting deiodination of [[T4]] to [[T3]] by the [[enzyme]] 5’-monodeiodinase. This is an [[adaptive]] process by which the [[Human body|body]] prevents further [[muscle]] and [[calorie]] loss.
** During these [[Stress (medicine)|stress]] conditions, there occurs [[hypermetabolism]], increased [[energy]] expenditure, [[hyperglycemia]], and [[muscle]] loss. It is speculated, that the body in order to contain this [[hypermetabolism]] induces some degree of [[hypothyroidism]] by inhibiting deiodination of [[T4]] to [[T3]] by the [[enzyme]] 5’-monodeiodinase. This is an [[adaptive]] process by which the [[Human body|body]] prevents further [[muscle]] and [[calorie]] loss.
** During illness, there is also [[downregulation]] of [[Thyrotropin-releasing hormone|TRH]] and [[Thyroid-stimulating hormone|TSH]] release from the [[hypothalamus]] and [[pituitary gland]] respectively. It may be signalled by a decrease in leptin caused by malnutrition. Under normal conditions, leptin prevents neuropeptide Y (NPY) and agouti-related protein (AGRP) induced downregulation of TRH.
** During illness, there is also [[downregulation]] of [[Thyrotropin-releasing hormone|TRH]] and [[Thyroid-stimulating hormone|TSH]] release from the [[hypothalamus]] and [[pituitary gland]] respectively. It may be signalled by a decrease in [[leptin]] caused by [[malnutrition]]. Under normal conditions, leptin prevents neuropeptide Y (NPY) and agouti-related protein (AGRP) induced downregulation of [[TRH]].
** [[In vitro]] studies have shown that high concentrations of [[cytokines]] severely affect [[genes]] involved in the production and release of [[T4]] and [[T3]].<ref name="pmid8940342">{{cite journal |vauthors=Boelen A, Maas MA, Lowik CW, Platvoet MC, Wiersinga WM |title=Induced illness in interleukin-6 (IL-6) knock-out mice: a causal role of IL-6 in the development of the low 3,5,3'-triiodothyronine syndrome |journal=Endocrinology |volume=137 |issue=12 |pages=5250–4 |year=1996 |pmid=8940342 |doi=10.1210/endo.137.12.8940342 |url=}}</ref>
** [[In vitro]] studies have shown that high concentrations of [[cytokines]] severely affect [[genes]] involved in the production and release of [[T4]] and [[T3]].
* [[Euthyroid]] sick syndrome presents with low serum [[T3]]. Depending upon the severity and duration of the [[Stress (medicine)|stress]] inducing [[condition]], the [[thyroid-stimulating hormone]]([[TSH]]), [[thyroxine]] ([[T4]]), and [[free T4]] ([[FT4]]) are affected in variable proportions. The drop in levels of [[T3]] and [[T4]] are more with more severe illnesses. [[Mortality rate]] is high when there is a marked decrease in serum [[T3]] and [[T4]].<ref name="GRASBERGERGOLCHER2002">{{cite journal|last1=GRASBERGER|first1=Helmut|last2=GOLCHER|first2=Henriette M.B.|last3=FINGERHUT|first3=Anja|last4=JANSSEN|first4=Onno E.|title=Loop variants of the serpin thyroxine-binding globulin: implications for hormone release upon limited proteolysis|journal=Biochemical Journal|volume=365|issue=1|year=2002|pages=311–316|issn=0264-6021|doi=10.1042/bj20020014}}</ref><ref name="pmid10554534">{{cite journal |vauthors=Schilling JU, Zimmermann T, Albrecht S, Zwipp H, Saeger HD |title=[Low T3 syndrome in multiple trauma patients--a phenomenon or important pathogenetic factor?] |language=German |journal=Med. Klin. (Munich) |volume=94 Suppl 3 |issue= |pages=66–9 |year=1999 |pmid=10554534 |doi= |url=}}</ref><ref name="WongHershman1992">{{cite journal|last1=Wong|first1=Timothy K.|last2=Hershman|first2=Jerome M.|title=Changes in thyroid function in nonthyroid illness|journal=Trends in Endocrinology & Metabolism|volume=3|issue=1|year=1992|pages=8–12|issn=10432760|doi=10.1016/1043-2760(92)90085-F}}</ref><ref name="DocterKrenning1993">{{cite journal|last1=Docter|first1=R.|last2=Krenning|first2=E. P.|last3=Jong|first3=M.|last4=Hennemann|first4=G.|title=The sick euthyroid syndrome: changes in thyroid hormone serum parameters and hormone metabolism|journal=Clinical Endocrinology|volume=39|issue=5|year=1993|pages=499–518|issn=0300-0664|doi=10.1111/j.1365-2265.1993.tb02401.x}}</ref><ref name="BartalenaBogazzi1998">{{cite journal|last1=Bartalena|first1=L|last2=Bogazzi|first2=F|last3=Brogioni|first3=S|last4=Grasso|first4=L|last5=Martino|first5=E|title=Role of cytokines in the pathogenesis of the euthyroid sick syndrome|journal=European Journal of Endocrinology|volume=138|issue=6|year=1998|pages=603–614|issn=0804-4643|doi=10.1530/eje.0.1380603}}</ref>
** Any chronic [[illness]] may impair [[plasma protein]] binding of [[thyroid hormones]], resulting in [[reduced]] levels of total hormones.
* [[Euthyroid]] sick syndrome presents with low serum [[T3]]. Depending upon the severity and duration of the [[Stress (medicine)|stress]] inducing [[condition]], the [[thyroid-stimulating hormone]]([[TSH]]), [[thyroxine]] ([[T4]]), and [[free T4]] ([[FT4]]) are affected in variable proportions. The drop in levels of [[T3]] and [[T4]] are more with more severe illnesses. [[Mortality rate]] is high when there is a marked decrease in serum [[T3]] and [[T4]].


==Genetics==
==Genetics==


Gene involved in the pathogenesis of euthyroid sick syndrome include mutation in LEP gene.
[[Pathogenesis]] of [[euthyroid]] sick syndrome include [[mutation]] in [[LEP]] gene.
*LEP gene mutation:<ref name="pmid9165050">{{cite journal |vauthors=Légrádi G, Emerson CH, Ahima RS, Flier JS, Lechan RM |title=Leptin prevents fasting-induced suppression of prothyrotropin-releasing hormone messenger ribonucleic acid in neurons of the hypothalamic paraventricular nucleus |journal=Endocrinology |volume=138 |issue=6 |pages=2569–76 |year=1997 |pmid=9165050 |doi=10.1210/endo.138.6.5209 |url=}}</ref><ref name="RoggeJones2008">{{cite journal|last1=Rogge|first1=G.|last2=Jones|first2=D.|last3=Hubert|first3=G. W.|last4=Lin|first4=Y.|last5=Kuhar|first5=M. J.|title=CART peptides: regulators of body weight, reward and other functions|journal=Nature Reviews Neuroscience|volume=9|issue=10|year=2008|pages=747–758|issn=1471-003X|doi=10.1038/nrn2493}}</ref><ref name="FroguelClément1998">{{cite journal|last1=Froguel|first1=Philippe|last2=Clément|first2=Karine|last3=Vaisse|first3=Christian|last4=Lahlou|first4=Najiba|last5=Cabrol|first5=Sylvie|last6=Pelloux|first6=Veronique|last7=Cassuto|first7=Dominique|last8=Gourmelen|first8=Micheline|last9=Dina|first9=Christian|last10=Chambaz|first10=Jean|last11=Lacorte|first11=Jean-Marc|last12=Basdevant|first12=Arnaud|last13=Bougnères|first13=Pierre|last14=Lebouc|first14=Yves|last15=Guy-Grand|first15=Bernard|journal=Nature|volume=392|issue=6674|year=1998|pages=398–401|issn=00280836|doi=10.1038/32911}}</ref><ref name="pmid16131331">{{cite journal |vauthors=Lechan RM, Fekete C |title=Role of thyroid hormone deiodination in the hypothalamus |journal=Thyroid |volume=15 |issue=8 |pages=883–97 |year=2005 |pmid=16131331 |doi=10.1089/thy.2005.15.883 |url=}}</ref>
*[[LEP]] gene [[mutation]]:<ref name="pmid9165050">{{cite journal |vauthors=Légrádi G, Emerson CH, Ahima RS, Flier JS, Lechan RM |title=Leptin prevents fasting-induced suppression of prothyrotropin-releasing hormone messenger ribonucleic acid in neurons of the hypothalamic paraventricular nucleus |journal=Endocrinology |volume=138 |issue=6 |pages=2569–76 |year=1997 |pmid=9165050 |doi=10.1210/endo.138.6.5209 |url=}}</ref><ref name="RoggeJones2008">{{cite journal|last1=Rogge|first1=G.|last2=Jones|first2=D.|last3=Hubert|first3=G. W.|last4=Lin|first4=Y.|last5=Kuhar|first5=M. J.|title=CART peptides: regulators of body weight, reward and other functions|journal=Nature Reviews Neuroscience|volume=9|issue=10|year=2008|pages=747–758|issn=1471-003X|doi=10.1038/nrn2493}}</ref><ref name="FroguelClément1998">{{cite journal|last1=Froguel|first1=Philippe|last2=Clément|first2=Karine|last3=Vaisse|first3=Christian|last4=Lahlou|first4=Najiba|last5=Cabrol|first5=Sylvie|last6=Pelloux|first6=Veronique|last7=Cassuto|first7=Dominique|last8=Gourmelen|first8=Micheline|last9=Dina|first9=Christian|last10=Chambaz|first10=Jean|last11=Lacorte|first11=Jean-Marc|last12=Basdevant|first12=Arnaud|last13=Bougnères|first13=Pierre|last14=Lebouc|first14=Yves|last15=Guy-Grand|first15=Bernard|title=A mutation in the human leptin receptor gene causes obesity and pituitary dysfunction|journal=Nature|volume=392|issue=6674|year=1998|pages=398–401|issn=00280836|doi=10.1038/32911}}</ref><ref name="pmid16131331">{{cite journal |vauthors=Lechan RM, Fekete C |title=Role of thyroid hormone deiodination in the hypothalamus |journal=Thyroid |volume=15 |issue=8 |pages=883–97 |year=2005 |pmid=16131331 |doi=10.1089/thy.2005.15.883 |url=}}</ref>
**The LEP gene encodes for leptin.
**The [[LEP]] [[gene]] encodes for [[leptin]].
**Normally, α-MSH stimulates TRH gene expression. Leptin enhances this effect of α-MSH on TRH gene expression.
**Normally, [[α-MSH]] stimulates [[TRH]] gene expression.  
**Leptin also decreases neuropeptide Y (NPY) and agouti-related protein (AGRP) induced decrease in TRH gene expression.
**[[Leptin]] enhances this effect of [[α-MSH]] on [[TRH]] gene expression.
** Any chronic illness or startvation can lead to decrease in leptin production.  
**[[Leptin]] also decreases [[neuropeptide Y]] (NPY) and [[Agouti-related peptide|agouti-related protein]] (AGRP) induced decrease in [[TRH]] gene expression.
**Patients who have a defective LEP or leptin receptor due to genetic mutations and who develop chronic illness later in life show reduced TRH secretion and features of euthyroid sick syndrome.<ref name="pmid18211669">{{cite journal |vauthors=Abo-Zenah HA, Shoeb SA, Sabry AA, Ismail HA |title=Relating circulating thyroid hormone concentrations to serum interleukins-6 and -10 in association with non-thyroidal illnesses including chronic renal insufficiency |journal=BMC Endocr Disord |volume=8 |issue= |pages=1 |year=2008 |pmid=18211669 |pmc=2254394 |doi=10.1186/1472-6823-8-1 |url=}}</ref><ref name="pmid7962327">{{cite journal |vauthors=Stouthard JM, van der Poll T, Endert E, Bakker PJ, Veenhof CH, Sauerwein HP, Romijn JA |title=Effects of acute and chronic interleukin-6 administration on thyroid hormone metabolism in humans |journal=J. Clin. Endocrinol. Metab. |volume=79 |issue=5 |pages=1342–6 |year=1994 |pmid=7962327 |doi=10.1210/jcem.79.5.7962327 |url=}}</ref><ref name="pmid14635503">{{cite journal |vauthors=Wawrzynska L, Sakowicz A, Rudzinski P, Langfort R, Kurzyna M |title=The conversion of thyroxine to triiodothyronine in the lung: comparison of activity of type I iodothyronine 5' deiodinase in lung cancer with peripheral lung tissues |journal=Monaldi Arch Chest Dis |volume=59 |issue=2 |pages=140–5 |year=2003 |pmid=14635503 |doi= |url=}}</ref>
** Any chronic [[illness]] or [[starvation]] can lead to decrease in [[leptin]] production.  
**Patients who have a defective [[LEP]] or [[leptin receptor]] due to [[genetic mutations]] and who develop chronic [[illness]] later in life show reduced [[TRH]] secretion and features of [[euthyroid]] sick syndrome.<ref name="pmid18211669">{{cite journal |vauthors=Abo-Zenah HA, Shoeb SA, Sabry AA, Ismail HA |title=Relating circulating thyroid hormone concentrations to serum interleukins-6 and -10 in association with non-thyroidal illnesses including chronic renal insufficiency |journal=BMC Endocr Disord |volume=8 |issue= |pages=1 |year=2008 |pmid=18211669 |pmc=2254394 |doi=10.1186/1472-6823-8-1 |url=}}</ref><ref name="pmid7962327">{{cite journal |vauthors=Stouthard JM, van der Poll T, Endert E, Bakker PJ, Veenhof CH, Sauerwein HP, Romijn JA |title=Effects of acute and chronic interleukin-6 administration on thyroid hormone metabolism in humans |journal=J. Clin. Endocrinol. Metab. |volume=79 |issue=5 |pages=1342–6 |year=1994 |pmid=7962327 |doi=10.1210/jcem.79.5.7962327 |url=}}</ref><ref name="pmid14635503">{{cite journal |vauthors=Wawrzynska L, Sakowicz A, Rudzinski P, Langfort R, Kurzyna M |title=The conversion of thyroxine to triiodothyronine in the lung: comparison of activity of type I iodothyronine 5' deiodinase in lung cancer with peripheral lung tissues |journal=Monaldi Arch Chest Dis |volume=59 |issue=2 |pages=140–5 |year=2003 |pmid=14635503 |doi= |url=}}</ref>


==Associated Conditions==
==Associated Conditions==
Euthyroid sick syndrome is seen with starvation and severe illness such as:<ref name="pmid26677087">{{cite journal |vauthors=Silva MH, Araujo MC, Diniz EM, Ceccon ME, Carvalho WB |title=Nonthyroidal illnesses syndrome in full-term newborns with sepsis |journal=Arch Endocrinol Metab |volume=59 |issue=6 |pages=528–34 |year=2015 |pmid=26677087 |doi=10.1590/2359-3997000000111 |url=}}</ref><ref name="pmid27403906">{{cite journal |vauthors=Frączek MM, Gackowski A, Przybylik-Mazurek E, Nessler J |title=[The relation between the low T3 syndrome in the clinical course of myocardial infarction and heart failure] |language=Polish |journal=Pol. Merkur. Lekarski |volume=40 |issue=240 |pages=380–3 |year=2016 |pmid=27403906 |doi= |url=}}</ref>
[[Euthyroid]] sick syndrome is seen with [[starvation]] and severe [[illness]] such as:<ref name="pmid26677087">{{cite journal |vauthors=Silva MH, Araujo MC, Diniz EM, Ceccon ME, Carvalho WB |title=Nonthyroidal illnesses syndrome in full-term newborns with sepsis |journal=Arch Endocrinol Metab |volume=59 |issue=6 |pages=528–34 |year=2015 |pmid=26677087 |doi=10.1590/2359-3997000000111 |url=}}</ref><ref name="pmid27403906">{{cite journal |vauthors=Frączek MM, Gackowski A, Przybylik-Mazurek E, Nessler J |title=[The relation between the low T3 syndrome in the clinical course of myocardial infarction and heart failure] |language=Polish |journal=Pol. Merkur. Lekarski |volume=40 |issue=240 |pages=380–3 |year=2016 |pmid=27403906 |doi= |url=}}</ref>
*Inflammatory condition
*[[Sepsis]]
*Sepsis
*[[Malignancy]]
*Malignancy
*[[Physical trauma|Trauma]]
*Trauma
*[[Surgery]]
*Surgery
*[[Burns]]
*Burns
*[[Bone marrow transplantation]]
*Bone marrow transplantation
*Other [[inflammatory]] conditions
*Metabolic disorders
*[[Metabolic disorders]]
*Any major condition of
*Any major condition of:
**Cardiovascular system: Myocardial infarction
**[[Cardiovascular system]]: [[Myocardial infarction]]
**Respiratory system : Pneumonia
**[[Respiratory system]] : [[Pneumonia]]
**Genitourinary system: Chronic renal failure
**[[Genitourinary system]]: [[Chronic renal failure]]
**Gastrointestinal system: Cirrhosis
**[[Gastrointestinal system]]: [[Cirrhosis]]


==Gross Pathology==
==Gross Pathology==
In euthyroid sick syndrome the thyroid gland does not appear to be dysfunctional.
In [[euthyroid]] sick syndrome the [[thyroid gland]] appears normal on gross pathology.


==Microscopic Pathology==
==Microscopic Pathology==
On microscopic histopathological analysis, euthyroid sick syndrome presents with normal thyroid histology.  
On [[microscopic]] [[histopathological]] analysis, [[euthyroid]] sick syndrome presents with normal [[thyroid]] histology.
[[image:Histology thyroid gland.jpg|thumb|center|Histology of normal thyroid gland. 1. Colloid 2. Cellular Epithelium Arrow: C-Cell ([https://commons.wikimedia.org/wiki/File:Histology_thyroid_gland.jpg Source - By M-J-G (Own work) [CC BY-SA 4.0, via Wikimedia Commons])]]


==References==
==References==

Latest revision as of 16:10, 4 November 2017

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

Overview

Euthyroid sick syndrome is not a primary thyroid disorder but instead results from changes induced by the nonthyroidal illness. The cause of euthyroid sick syndrome is multifactorial. It is thought that euthyroid sick syndrome is the result of severe illness and inflammation. During these stress conditions, hypermetabolism occur, that lead to increased energy expenditure, hyperglycemia, and muscle loss. It is speculated, that the body induces some degree of hypothyroidism by inhibiting deiodination of T4 to T3 by the enzyme 5’-monodeiodinase, in order to contain the hypermetabolism. This is an adaptive process by which the body prevents further muscle and calorie loss. Inflammation leads to increased production of cytokines that severely affects genes involved in the production and release of T4 and T3. There is also downregulation of TRH and TSH release from the hypothalamus and pituitary gland respectively. This downregulation may be signalled by a decrease in leptin caused by malnutrition. On gross pathology, euthyroid sick syndrome, does not appear to be dysfunctional. On microscopic histopathological analysis, euthyroid sick syndrome presents with normal thyroid histology.

Pathophysiology

Pathogenesis

Genetics

Pathogenesis of euthyroid sick syndrome include mutation in LEP gene.

Associated Conditions

Euthyroid sick syndrome is seen with starvation and severe illness such as:[14][15]

Gross Pathology

In euthyroid sick syndrome the thyroid gland appears normal on gross pathology.

Microscopic Pathology

On microscopic histopathological analysis, euthyroid sick syndrome presents with normal thyroid histology.

Histology of normal thyroid gland. 1. Colloid 2. Cellular Epithelium Arrow: C-Cell (Source - By M-J-G (Own work) [CC BY-SA 4.0, via Wikimedia Commons)

References

  1. ↑ Boelen A, Maas MA, Lowik CW, Platvoet MC, Wiersinga WM (1996). "Induced illness in interleukin-6 (IL-6) knock-out mice: a causal role of IL-6 in the development of the low 3,5,3'-triiodothyronine syndrome". Endocrinology. 137 (12): 5250–4. doi:10.1210/endo.137.12.8940342. PMID 8940342.
  2. ↑ GRASBERGER, Helmut; GOLCHER, Henriette M.B.; FINGERHUT, Anja; JANSSEN, Onno E. (2002). "Loop variants of the serpin thyroxine-binding globulin: implications for hormone release upon limited proteolysis". Biochemical Journal. 365 (1): 311–316. doi:10.1042/bj20020014. ISSN 0264-6021.
  3. ↑ Schilling JU, Zimmermann T, Albrecht S, Zwipp H, Saeger HD (1999). "[Low T3 syndrome in multiple trauma patients--a phenomenon or important pathogenetic factor?]". Med. Klin. (Munich) (in German). 94 Suppl 3: 66–9. PMID 10554534.
  4. ↑ Wong, Timothy K.; Hershman, Jerome M. (1992). "Changes in thyroid function in nonthyroid illness". Trends in Endocrinology & Metabolism. 3 (1): 8–12. doi:10.1016/1043-2760(92)90085-F. ISSN 1043-2760.
  5. ↑ Docter, R.; Krenning, E. P.; Jong, M.; Hennemann, G. (1993). "The sick euthyroid syndrome: changes in thyroid hormone serum parameters and hormone metabolism". Clinical Endocrinology. 39 (5): 499–518. doi:10.1111/j.1365-2265.1993.tb02401.x. ISSN 0300-0664.
  6. ↑ Bartalena, L; Bogazzi, F; Brogioni, S; Grasso, L; Martino, E (1998). "Role of cytokines in the pathogenesis of the euthyroid sick syndrome". European Journal of Endocrinology. 138 (6): 603–614. doi:10.1530/eje.0.1380603. ISSN 0804-4643.
  7. ↑ Légrádi G, Emerson CH, Ahima RS, Flier JS, Lechan RM (1997). "Leptin prevents fasting-induced suppression of prothyrotropin-releasing hormone messenger ribonucleic acid in neurons of the hypothalamic paraventricular nucleus". Endocrinology. 138 (6): 2569–76. doi:10.1210/endo.138.6.5209. PMID 9165050.
  8. ↑ Rogge, G.; Jones, D.; Hubert, G. W.; Lin, Y.; Kuhar, M. J. (2008). "CART peptides: regulators of body weight, reward and other functions". Nature Reviews Neuroscience. 9 (10): 747–758. doi:10.1038/nrn2493. ISSN 1471-003X.
  9. ↑ Froguel, Philippe; Clément, Karine; Vaisse, Christian; Lahlou, Najiba; Cabrol, Sylvie; Pelloux, Veronique; Cassuto, Dominique; Gourmelen, Micheline; Dina, Christian; Chambaz, Jean; Lacorte, Jean-Marc; Basdevant, Arnaud; Bougnères, Pierre; Lebouc, Yves; Guy-Grand, Bernard (1998). "A mutation in the human leptin receptor gene causes obesity and pituitary dysfunction". Nature. 392 (6674): 398–401. doi:10.1038/32911. ISSN 0028-0836.
  10. ↑ Lechan RM, Fekete C (2005). "Role of thyroid hormone deiodination in the hypothalamus". Thyroid. 15 (8): 883–97. doi:10.1089/thy.2005.15.883. PMID 16131331.
  11. ↑ Abo-Zenah HA, Shoeb SA, Sabry AA, Ismail HA (2008). "Relating circulating thyroid hormone concentrations to serum interleukins-6 and -10 in association with non-thyroidal illnesses including chronic renal insufficiency". BMC Endocr Disord. 8: 1. doi:10.1186/1472-6823-8-1. PMC 2254394. PMID 18211669.
  12. ↑ Stouthard JM, van der Poll T, Endert E, Bakker PJ, Veenhof CH, Sauerwein HP, Romijn JA (1994). "Effects of acute and chronic interleukin-6 administration on thyroid hormone metabolism in humans". J. Clin. Endocrinol. Metab. 79 (5): 1342–6. doi:10.1210/jcem.79.5.7962327. PMID 7962327.
  13. ↑ Wawrzynska L, Sakowicz A, Rudzinski P, Langfort R, Kurzyna M (2003). "The conversion of thyroxine to triiodothyronine in the lung: comparison of activity of type I iodothyronine 5' deiodinase in lung cancer with peripheral lung tissues". Monaldi Arch Chest Dis. 59 (2): 140–5. PMID 14635503.
  14. ↑ Silva MH, Araujo MC, Diniz EM, Ceccon ME, Carvalho WB (2015). "Nonthyroidal illnesses syndrome in full-term newborns with sepsis". Arch Endocrinol Metab. 59 (6): 528–34. doi:10.1590/2359-3997000000111. PMID 26677087.
  15. ↑ Frączek MM, Gackowski A, Przybylik-Mazurek E, Nessler J (2016). "[The relation between the low T3 syndrome in the clinical course of myocardial infarction and heart failure]". Pol. Merkur. Lekarski (in Polish). 40 (240): 380–3. PMID 27403906.

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