View source for Anorexia (symptom)

{{Short description|Loss of appetite}}
{{Other uses|Anorexia (disambiguation)|}}
{{Infobox medical condition
| name = Anorexia
| image = 
| specialty = [[Gastroenterology]], [[family medicine]], [[internal medicine]]
| symptoms = Not wanting to eat, no hunger, dizziness, weakness
| complications = 
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| types = 
| causes = [[Stomachache|Achy stomach]], [[gastroparesis]], [[Foodborne illness|food poisoning]]
| risks = 
| diagnosis = 
| differential = 
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}}

'''Anorexia''' is a medical term for a '''loss of [[appetite]]'''. While the term outside of the scientific literature is often used interchangeably with [[anorexia nervosa]], many possible causes exist for a loss of appetite, some of which may be harmless, while others indicate a serious clinical condition or pose a significant risk.

Anorexia in this usage is a [[symptom]], not a [[diagnosis]].

The symptom also occurs in non-human animals, such as cats,<ref>{{Cite journal|last=Chan|first=Daniel L.|date=November 1, 2009|title=The Inappetent Hospitalised Cat: Clinical Approach to Maximising Nutritional Support|journal=Journal of Feline Medicine and Surgery|volume=11|issue=11|pages=925–933|doi=10.1016/j.jfms.2009.09.013|pmid=19857855|s2cid=20998698|doi-access=free|pmc=11383021}}</ref><ref name=CatAnorexia>{{Cite web|title=Anorexia|url=https://www.vet.cornell.edu/departments-centers-and-institutes/cornell-feline-health-center/health-information/feline-health-topics/anorexia|access-date=July 19, 2020|website=Cornell Feline Health Center|date=16 October 2017 |publisher=[[Cornell University]]}}</ref> dogs,<ref>{{Cite web|last1=Carrozza|first1=Amanda|last2=Marks|first2=Stanley|date=November 20, 2018|title=NY Vet: The Best Approach to Treating Inappetence|url=https://www.americanveterinarian.com/news/ny-vet-the-best-approach-to-treating-inappetence|url-status=live|archive-url=https://web.archive.org/web/20200719093002/https://www.americanveterinarian.com/news/ny-vet-the-best-approach-to-treating-inappetence|archive-date=July 19, 2020|access-date=July 19, 2020|website=American Veterinarian}}</ref><ref name=DogAnorexia>{{Cite web|last1=Llera|first1=Ryan|last2=Downing|first2=Robin|title=Anorexia in Dogs|url=https://vcahospitals.com/know-your-pet/anorexia-in-dogs|url-status=live|archive-url=https://web.archive.org/web/20200719095051/https://vcahospitals.com/know-your-pet/anorexia-in-dogs|archive-date=July 19, 2020|access-date=July 19, 2020|website=VCA Animal Hospital}}</ref> cattle, goats, and sheep.<ref>{{Cite web|last1=Jubb|first1=Tristan|last2=Perkins|first2=Nigel|title=Inappetence/Inanition|url=http://www.veterinaryhandbook.com.au/Diseases.aspx?speciesid=&syndromeid=9&diseasenameid=124&id=49|url-status=live|archive-url=https://web.archive.org/web/20200719094622/http://www.veterinaryhandbook.com.au/Diseases.aspx?speciesid=&syndromeid=9&diseasenameid=124&id=49|archive-date=July 19, 2020|access-date=July 19, 2020|website=Veterinary Handbook for the Livestock Export Industry|publisher=Australian Livestock Export Corporation, Meat & Livestock Australia}}</ref> In these species, anorexia may be referred to as '''inappetence'''. As in humans, loss of appetite can be due to a range of diseases and conditions, as well as environmental and psychological factors.<ref name=CatAnorexia/><ref name=DogAnorexia/>

== Etymology ==
The term is from {{Langx|grc|ανορεξία}} ({{lang|grc|ἀν-}}, 'without' + {{lang|grc|όρεξις}}, spelled {{transliteration|grc|[[orexis|órexis]]}}, meaning 'appetite').<ref name="Psyhogeos2016">{{cite book |last=Psyhogeos|first=Matina|date=14 April 2016|title=English Words Deriving from the Greek Language|publisher=Page Publishing Incorporated |url=https://books.google.com/books?id=1CX4CwAAQBAJ&pg=PT159|editor=Page Publishing Inc.|isbn=978-1682134283}}</ref>

== Common manifestations ==
Anorexia simply manifests as a decreased or loss of appetite. This can [[Presentation (medical)|present]] as not feeling hungry or lacking the desire to eat.<ref>{{Cite web|title=Loss of Appetite - Digestive Disorders|url=https://www.merckmanuals.com/en-ca/home/digestive-disorders/symptoms-of-digestive-disorders/loss-of-appetite|access-date=2021-10-27|website=Merck Manuals Consumer Version|language=en-CA}}</ref> Sometimes people do not even notice they lack an appetite until they begin to lose weight from eating less. In other cases, it can be more noticeable, such as when a person becomes nauseated from just the thought of eating. Any form of decreased appetite that leads to changes in the body (such as weight loss or muscle loss) and is not done intentionally as part of dieting is clinically significant.<ref name=":2">{{Cite book|title=Endocrinology: Adult and Pediatric|last=Jameson|first=Larry|publisher=Saunders|year=2016|isbn=978-0-323-18907-1|location=Philadelphia, PA|pages=506–510}}</ref>

== Physiology of anorexia ==
[[Appetite]] stimulation and suppression is a complex process involving many different parts of the brain and body by the use of various hormones and signals. Appetite is thought to be stimulated by interplay between peripheral signals to the brain (taste, smell, sight, gut hormones) as well as the balance of [[neurotransmitter]]s and [[neuropeptide]]s  in the [[hypothalamus]].<ref name=":2" /> Examples of these signals or hormones include [[neuropeptide Y]], [[leptin]], [[ghrelin]], [[insulin]], [[serotonin]], and [[orexin]]s (also called hypocretins). Anything that causes an imbalance of these signals or hormones can lead to the symptom of anorexia. While it is known that these signals and hormones help control appetite, the complicated mechanisms regarding a pathological increase or decrease in appetite are still being explored.<ref name=":2"/>

==Common causes==

*[[Abdominal pain]]
*[[Acute radiation syndrome]]
*[[Attention deficit hyperactivity disorder|ADHD]]
*[[Addison's disease]]
*[[Alcoholism]]
*[[Alcohol withdrawal syndrome|Alcohol withdrawal]]
*[[Anemia]]
*[[Anorexia nervosa]]
*[[Anxiety]]
*[[Appendicitis]]
*[[Babesiosis]]
*[[Benzodiazepine withdrawal syndrome|Benzodiazepine withdrawal]]
*[[Bipolar disorder]]
*[[Bronchitis]]
*[[Cancer]]<ref>{{Cite web|title=Loss of Appetite|url=https://www.cancer.org/treatment/treatments-and-side-effects/physical-side-effects/eating-problems/poor-appetite.html|access-date=2021-10-27|website=www.cancer.org|language=en}}</ref><ref>{{Cite web|title=Loss of appetite|url=https://cancer.ca/en/treatments/side-effects/loss-of-appetite|url-status=live|website=Canadian Cancer Society|date=December 2019 |archive-url=https://web.archive.org/web/20211027134339/https://cancer.ca/en/treatments/side-effects/loss-of-appetite |archive-date=2021-10-27 }}</ref>
*[[Cannabinoid hyperemesis syndrome]]
*[[Cannabis (drug)|Cannabis]] [[Drug withdrawal|withdrawal]]
*[[Celiac disease]]<ref name="GeneReviewsCD2015">{{cite web |url=https://www.ncbi.nlm.nih.gov/books/NBK1727/|title=Celiac Disease|vauthors=Taylor AK, Lebwohl B, Snyder CL, Green PH|publisher=GeneReviews®|date=17 September 2015|pmid=20301720 |access-date=24 September 2017}}</ref>
*[[Chronic kidney disease]]
*[[Chronic pain]]
*[[Common cold]]
*[[Constipation]]
*[[Chronic obstructive pulmonary disease|COPD]]
*[[COVID-19]]
*[[Crohn's disease]]
*[[Cystic fibrosis]]
*[[Dehydration]]
*[[Dementia]]
*[[Depression (mood)|Depression]]
*[[Diabetes]]
*[[Ebola]]
*[[Fatty liver disease]]
*[[Fever]]
*[[Foodborne illness|Food poisoning]]
*[[Gastroparesis]]
*[[Heart failure]]
*[[Hepatitis]]
*[[HIV/AIDS]]
*[[Hypercalcemia]]
*[[Hyperglycemia]]
*[[Hypervitaminosis D]]
*[[Hypothyroidism]] and sometimes [[hyperthyroidism]]
*[[Infection]]
*[[Influenza]]
*[[Irritable bowel syndrome]]
*[[Ketoacidosis]]
*[[Kidney failure]]<ref>{{Cite news|url=https://www.emedicinehealth.com/script/main/mobileart-emh.asp?articlekey=80651&questionid=7|title=Pinworms in Kids & Adults: Pictures, Symptoms & Treatments Viewer Comments and Reviews: Hypothyroidism - Symptoms - Patients Share Their Knowledge on eMedicineHealth|work=eMedicineHealth|access-date=2017-11-28|archive-date=2015-10-04|archive-url=https://web.archive.org/web/20151004020557/http://www.emedicinehealth.com/script/main/mobileart-emh.asp?articlekey=80651&questionid=7|url-status=dead}}</ref>
*[[Hypotension|Low blood pressure]]
*[[Macroglossia]]
*[[Mania]]
*[[Metabolic disorders]], particularly [[urea cycle disorders]]
*[[MELAS syndrome]]
*[[Nausea]]
*[[Old age]]
*[[Opioid use disorder]]
*[[Pancreatitis]]
*[[Pernicious anemia]] ([[Vitamin B12 deficiency|vitamin B<sub>12</sub> deficiency]])
*[[Pneumonia]]
*[[Psychosis]]
*[[Salmonellosis]]
*[[Schizophrenia]]
*[[Side effect]] of [[drug]]s
*[[Stimulant use disorder]]
*[[Stomach flu]]
*[[Stress (biology)|Stress]]
*[[Sickness behavior]]<ref>{{Cite journal|last1=Exton|first1=M. S.|title=Infection-Induced Anorexia: Active Host Defence Strategy|doi=10.1006/appe.1997.0116|journal=Appetite|volume=2|issue=3|pages=369–383|year=1997|pmid=9468766|s2cid=10465902}}</ref><ref>{{Cite journal|last1=Murray|first1=M. J.|last2=Murray|first2=A. B.|title=Anorexia of infection as a mechanism of host defense|journal=The American Journal of Clinical Nutrition|volume=32|issue=3|pages=593–596|year=1979|pmid=283688|doi=10.1093/ajcn/32.3.593}}</ref>
*[[Superior mesenteric artery syndrome]]
*[[Syndrome of inappropriate antidiuretic hormone secretion]]<ref>{{cite journal |last1=Winston |first1=Anthony P |title=The clinical biochemistry of anorexia nervosa |journal=Annals of Clinical Biochemistry: International Journal of Laboratory Medicine |date=March 2012 |volume=49 |issue=2 |pages=132–143 |doi=10.1258/acb.2011.011185|pmid=22349551 |s2cid=207193656 |doi-access=free }}</ref>
*[[Tobacco smoking]]
*[[Tuberculosis]]
*[[Thalassemia]]
*[[Ulcerative colitis]]
*[[Uremia]]<ref>{{cite journal |last1=Aguilera |first1=A |last2=Selgas |first2=R |last3=Codoceo |first3=R |last4=Bajo |first4=A |title=Uremic anorexia: a consequence of persistently high brain serotonin levels? The tryptophan/serotonin disorder hypothesis. |journal=Peritoneal Dialysis International |date=November 2000 |volume=20 |issue=6 |pages=810–6 |doi=10.1177/089686080002000648 |pmid=11216590|s2cid=1731116 |doi-access=free }}</ref>
*[[Folate deficiency]]
*[[Zinc deficiency]]

===Drugs===
{{main | Anorectic}}
*[[Stimulant]]s, such as [[ephedrine]], [[amphetamine]], [[methamphetamine]], [[MDMA]], [[cathinone]], [[methylphenidate]], [[cocaine]], etc.
*[[Horomone|Hormone]]s which are produced by [[adrenal glands]] and used as medication such as [[adrenaline]].
*[[Narcotic]]s, such as [[heroin]], [[morphine]], [[codeine]], [[hydrocodone]], [[oxycodone]], etc.
*[[Antidepressants]] may have anorexia as a side effect, primarily [[selective serotonin reuptake inhibitor]]s (SSRIs) such as [[fluoxetine]].
* [[Exenatide|Byetta]], a [[Type 2 diabetes|type II diabetes]] drug, will cause moderate nausea and loss of appetite.
* Abruptly stopping appetite-increasing drugs, such as [[cannabis (drug)|cannabis]] and [[corticosteroid]]s.
* Chemicals that are members of the [[phenethylamine]] group. (Individuals with anorexia nervosa may seek them to suppress appetite.)
*[[Topiramate]] may cause anorexia as a side effect.
* Other drugs may be used to intentionally cause anorexia in order to help a patient [[fasting|preoperative fasting]] prior to [[general anesthesia]]. It is important to avoid food before surgery to mitigate the risk of [[pulmonary aspiration]], which can be fatal.

===Other===
* During the post-operative recovery period for a [[tonsillectomy]] or [[adenoidectomy]], it is common for adult patients to experience a lack of appetite until their throat significantly heals (usually 10–14 days).<ref>{{cite web|url=http://www.umhc.com/oth/Page.asp?PageID=OTH001009|title=Home Care After Tonsillectomy and Adenoidectomy|url-status=dead|archive-url=https://web.archive.org/web/20110717153234/http://www.umhc.com/oth/Page.asp?PageID=OTH001009|archive-date=July 17, 2011}}</ref>
* [[Allergy]]
* [[Altitude sickness]]
* [[Airsickness]]
* Significant [[Broken heart|emotional pain]] caused by an event (rather than a [[mental disorder]]) can cause an individual to temporarily lose all interest in food.
* Several [[Twelve-step program]]s including [[Overeaters Anonymous]] tackle psychological issues members believe lead to forms of [[Relative deprivation|deprivation]]
* [[Psychological stress]]
* [[Toothache]]
* Experiencing grotesque, unpleasant or unappealing thoughts or conversations
* Being in the presence of unappealing things such as waste matter, dead organisms, or bad smells

==Complications==
Complications of anorexia may result due to poor food intake. Poor food intake can lead to [[dehydration]], [[electrolyte imbalance]]s, [[anemia]] and [[Malnutrition|nutritional deficiencies]]. These imbalances will worsen the longer that food is avoided.<ref name=":2"/>

===Sudden cardiac death===
Anorexia is a relatively common condition that can lead patients to have dangerous electrolyte imbalances, leading to acquired [[long QT syndrome]] which can result in [[sudden cardiac death]]. This can develop over a prolonged period of time, and the risk is further heightened when feeding resumes after a period of abstaining from consumption.<ref name=":0"/>

=== Refeeding syndrome ===
Care must be taken when a patient begins to eat after prolonged starvation to avoid the potentially fatal complications of [[refeeding syndrome]]. The initial signs of refeeding syndrome are minimal, but can rapidly progress to death. Thus, the reinitiation of food or oral intake is usually started slowly and requires close observation under supervision by trained healthcare professionals. This is usually done in a hospital or nutritional rehabilitation center.<ref name=":0">{{cite journal|last1=Jáuregui-Garrido|first1=B.|last2=Jáuregui-Lobera|first2=I.|title=Sudden death in eating disorders|journal=Vascular Health and Risk Management|date=2012|volume=8|pages=91–98|pmid=22393299|pmc=3292410|doi=10.2147/VHRM.S28652 |doi-access=free }}</ref>

== Management ==
Anorexia can be treated with the help of [[orexigenic]] drugs.<ref>{{Cite journal |last=Thomas |first=David R. |date=February 2006 |title=Guidelines for the Use of Orexigenic Drugs in Long-Term Care |url=http://doi.wiley.com/10.1177/011542650602100182 |journal=Nutrition in Clinical Practice |language=en |volume=21 |issue=1 |pages=82–87 |doi=10.1177/011542650602100182 |pmid=16439773 |issn=0884-5336|url-access=subscription }}</ref><ref>{{Cite journal |last1=Viswambharan |first1=Vishal |last2=Manepalli |first2=Jothika N |last3=Grossberg |first3=George T |date=February 2013 |title=Orexigenic agents in geriatric clinical practice |url=https://www.futuremedicine.com/doi/10.2217/ahe.12.83 |journal=Aging Health |language=en |volume=9 |issue=1 |pages=49–65 |doi=10.2217/ahe.12.83 |issn=1745-509X|url-access=subscription }}</ref>

==References==
{{Reflist}}

{{Medical resources
| MedlinePlus =000362
| ICD10 = {{ICD10|R|63|0|r|50}}
| ICD9 = {{ICD9|783.0}} 
| MeshID = D000855
}}
{{Nutritional pathology}}
{{General symptoms and signs}}{{Digestive system and abdomen symptoms and signs}}{{Common Cold}}

{{Authority control}}

[[Category:Symptoms and signs: Endocrinology, nutrition, and metabolism]]
[[Category:Eating disorders]]