Anorexia (symptom)

Overview
Anorexia (deriving from the Greek "α(ν)-" (a(n)-, a prefix that denotes absence) + "όρεξη'' (orexe) = appetite) is the decreased sensation of appetite. While the term in non-scientific publications is often used interchangeably with anorexia nervosa, many possible causes exist for a decreased appetite, some of which may be harmless, while others indicate a serious clinical condition, or pose a significant risk.

Common causes
The most common form of anorexia is simply satiation following the consumption of food. This happens in all normal humans and is called postprandial anorexia. Disorders that cause (harmful) anorexia include anorexia nervosa, severe depression, cancer, dementia, AIDS, and chronic renal failure and the use of certain drugs, particularly stimulants and narcotics. Environmentally induced disorders such as altitude sickness can also trigger an acute form of anorexia. Anorexia may also be seen in congestive heart failure, perhaps due to congestion of the liver with venous blood.

Although the presenting symptom (the one which prompts a patient to seek medical attention) in acute appendicitis is abdominal pain, patients virtually always experience anorexia as well, possibly accompanied by an early episode of vomiting.

Some medications, antidepressants for example, can have anorexia as a side effect. Most notoriously, however, chemicals that are a member of the phenethylamine family are known to have more intense anorectic properties. For this reason, many individuals suffering from anorexia nervosa may seek to use these medications to suppress appetite. Such prescription medications include Ritalin, Adderall, Dexedrine, and Desoxyn. In some cases, these medications are prescribed to patients prior to undergoing an operation requiring general anesthesia. This is a prophylactic measure taken to ensure no food will back up into the esophagus and cause the patient to stop breathing during the procedure.

Complete Differential Diagnosis of Causes of Anorexia (alphabetical):

 * Aciclovir
 * Acute fatty liver of pregnancy
 * Acute radiation syndrome
 * Acute viral nasopharyngitis (common cold)
 * AIDS
 * Amphetamine
 * Amphotericin B
 * Anorexia nervosa
 * Antidepressants
 * Appendicitis
 * Astroviridae
 * Atypical pneumonia
 * Benzylpiperazine
 * Binge eating
 * Borderline personality disorder
 * Bulimia
 * Calcitriol
 * Carotenodermia
 * Chagas disease
 * Chromotherapy
 * Chronic fatigue syndrome
 * Chronic mountain sickness
 * Chronic renal failure
 * Clinical depression
 * Cocaine
 * Colorectal cancer
 * Community-acquired pneumonia
 * Congestive heart failure
 * Craniopharyngioma
 * Crohn's Disease
 * Cryptosporidium parvum
 * Cytauxzoonosis
 * Defensive vomiting
 * Dementia
 * Depression
 * Dextromethamphetamine
 * Dextromethylphenidate
 * Diabetic nephropathy
 * Diacetylmorphine
 * Encephalitis
 * Enfuvirtide
 * Fluconazole
 * Gold salts
 * Hangover
 * Hepatitis
 * Hepatitis E
 * High altitude
 * Hydralazine
 * Hymenolepiasis
 * Hypercalcemia
 * Hypervitaminosis D
 * Ketorolac
 * Lábrea fever
 * Leptoprin
 * Marbofloxacin
 * Mastoiditis
 * Medical cannabis
 * Methylphenidate
 * Milk-alkali syndrome
 * Mirtazapine
 * Modafinil
 * Moxifloxacin
 * Mumps
 * Non-Hodgkin lymphoma
 * Obsessive-compulsive disorder
 * Opioid dependency
 * Oropouche fever
 * Orthorexia nervosa
 * Panic disorder
 * Pipradrol
 * Pneumonia
 * Pott's disease
 * Pyrazinamide
 * Relapsing fever
 * Retinoid
 * Rhinovirus
 * Sporotrichosis
 * St John's wort
 * Stimulants
 * Superior mesenteric artery syndrome
 * Theobromine
 * Ulcerative colitis
 * Valaciclovir
 * Vitamin A
 * Ziconotide
 * Zopiclone