Eating disorder of psychiatric origin. Affects around 0.5 % of the population in wealthy Western countries. It appears around puberty, affecting girls in over 90 % of cases. It becomes chronic in adulthood in around 20 % of cases. The main cause is the fear of gaining weight or becoming obese, and is expressed by a disturbance in the perception of one's body dimensions and shapes. 

There are two types: 

-         the restrictive type: weight loss mainly through dieting or fasting, often accompanied by physical hyperactivity (excessive exercise).

-         the bulimia/vomiting type: subjects make themselves vomit after binge eating crises, use of laxatives and diuretics to lose weight.

Depending on the context, the term “undernutrition” or “anorexia” is used when the BMI is below 16.5.

The following behavioral traits are often observed

-         denial of the seriousness of current thinness.

-         obsession with food 

-         poor self-image 

-         control: great determination and unflappable self-organization.

-         perfectionism.

-         physical hyperactivity

Physiological consequences :

-         cardiovascular: hypotension (often orthostatic) and bradycardia; reduced myocardial mass and preload; electrolyte-induced QTc prolongation

-         respiratory: hypoventilation to compensate for metabolic alkalosis (vomiting, laxatives); risk of pharyngotracheal lesions in case of frequent vomiting

-         gastrointestinal: gastritis, delayed gastric emptying; risk of superior mesenteric artery syndrome (post-prandial vomiting) and duodenal ischemia (see this term); in case of voluntary vomiting: risk of Mallory-Weiss syndrome (see this term); increased liver enzymes are a sign of severity (frequent hypoglycemia; risk of hepatic steatosis on refeeding).

-         endocrine: pseudohypothyroidism, loss of circadian cortisol rhythm, hypomenorrhea or secondary amenorrhea, osteoporosis

-         renal: lithiasis; renal failure due to reduced glomerular filtration: creatinine remains low due to reduced muscle mass; activation of the renin-angiotensin system aggravates hypokalemia

-         hematological: anemia, leukopenia with reduced immunity

-         neurological: reversible reduction in gray and white matter, cognitive disorders

Management: psychotherapy, progressive refeeding.

Renutrition syndrome: when calories are reintroduced too quickly, glycolysis increases, with a reduction in blood phosphate (to synthesize ATP) and a major risk of hypophosphatemia (< 0.5 mmol/L). Thiamine (vit B1) deficiency can lead to hyperlactacidemia, as pyruvate is converted into lactates rather than glucose.

Recommendations to prevent renutrition syndrome: 

-         correct deficiencies in K, Mg, P

-         thiamine 100 mg/d IV then p os for at least 5-7 days

-         start with 10-20 kcal/kg/day on the first day

-         increase caloric intake by 33 % every 1-2 days, depending on biological results

Anesthetic implications: 

Check ionogram (Na, K, Ca, Mg), blood glucose, albumin, hemoglobin and leukocytes, ECG (QT) and cardiac ultrasound (muscle mass, mitral valve prolapse).

Check renal function: caution: blood creatinine is unreliable.

Monitor blood sugar levels. Gastric ultrasound before induction: dilatation ?

Dosage of anesthetic agents according to actual weight.

In case of lactic acidosis or hyperlactacidemia: administer IV thiamine (see thiamine deficiency).

Risk of postoperative conversion hysteria.

Do not attempt to correct undernutrition quickly: risk of renutrition syndrome. Beware of hidden caloric intake: glucose, propofol excipient (1.1 kcal/ml)...

References :

-        Seller CA, Ravalia A.
Anaesthetic implications of anorexia nervosa.
Anaesthesia 2003 ; 58 : 437-43

-        Hirose K, Hirose M, Tanaka K, Kawahito S, Tamaki T, Oshita S.
Perioperative management of severe anorexia nervosa.
Brit J Anaesth 2014;112 : 246-54

-        van den Berg JP, Elgersma HJ, Zeillemaker-Hoekstra M.
Anorexia nervosa: practical implications for the anaesthetist.
BJA Education 2023 ; 23: 17-23        

Updated: March 2025