Anorexia Nervosa

The most important feature of patients with anorexia nervosa is the refusal to maintain even low-normal body weight.

Epidemiology

• Seen in 1 in 200 individuals and mortality rate is 5% per decade
• Essentially occurs only in cultures in which thinness is valued

Diagnostic criteria from DSM Manual

• Refusal to maintain body weight at or above minimally normal weight for age and height (eg, weight loss leading to maintenance of body weight less than 85% of that expected or failure to make expected weight gain during period of growth, leading to bodyweight less than 85% of that expected).
• Intense fear of gaining weight or becoming fat, even though underweight.
• Disturbance in the way in which one's body weight or shape is experienced, undue influence of body weight or shape on self-evaluation, or denial of the seriousness of the current low body weight.
• In postmenopausal females, amenorrhea ie, the absence of at least three consecutive cycles. (A woman is considered to have amenorrhea if her periods occur only following hormone, eg, oestrogen administration.)

Summary

There is a distorted self-image with control of body weight through dieting, purging, vomiting and diuretics and exercise. There is actually quite a degree of overlap and patients can flit from one group to the other of AN or BN. There is a significant history of sexual abuse in those with eating disorders and the subject should be broached once there is a good therapeutic relationship between clinician and patient

Arrhythmias

• Patients with anorexia may be susceptible to ventricular arrhythmias such as torsade due to long QT seen with severe electrolyte imbalances.
• Be careful with drugs like macrolides and some antihistamines which lengthen QT. The diagnosis of Anorexia requires a BMI less than 85% of the expected weight

Types

• Restricting Type: During the current episode of anorexia nervosa, the person has not regularly engaged in binge-eating or purging behaviour (ie, self-induced vomiting or the misuse of laxatives, diuretics, or enemas).
• Binge-Eating/Purging Type: During the current episode of anorexia nervosa, the person has regularly engaged in binge-eating or purging behaviour (ie, self-induced vomiting or the misuse of laxatives, diuretics, or enemas)..

Investigations

• All these are Low Potassium, Chloride, Calcium, Magnesium and Phosphate - weakness, muscle weakness, heart failure, death, Low Zinc, Bone mineral density, Albumin, Glucose, Hb, WCC, T3, LH and FSH, Iron B12 Folate
• All these are raised AST, ALT, amylase, Raised cholesterol, Raised GH and cortisol, Urea/Creatinine if renal failure, Hypercarotinaemia, pH (Hypochloraemic alkalosis )
• CT Head scan in Anorexia Nervosa shows cerebral atrophy which is also called pseudo atrophy as it normalises with feeding and is due to enlargement of the ventricles

Clinical

• Low BMI, Hypothermia, Lanugo hair
• Loss of muscle mass, Dependent oedema
• Bradycardia - prolonged QT may be seen
• Hypotension, Neuropathy
• Bulimics - dental caries, halitosis, enlarged salivary glands

Poor prognostic indicators in anorexia nervosa include

• a prolonged initial illness, severe weight loss
• an older age at onset, bulimic tendencies
• relationship difficulties, personality difficulties