Diagnosis and subtypes

Eating disorders are characterised by persistent disturbance of eating or eating-related behaviour which leads to altered intake or absorption of food and causes significant impairment to health and psychosocial functioning.

Diagnosis of an eating disorder is based on the person's history, suggestive clinical features, and supported, where possible, by corroboration from a relative or friend.

Clinicians should be aware that assessment may appear normal even in medically unstable people.

Bulimia nervosa

Recurrent episodes of uncontrolled eating (binge eating)

Compensatory behaviour such as self-induced vomiting, laxative abuse or excessive exercise.

Weight is often within normal limits or just above

Binge eating disorder

Recurrent episodes of binge eating in the absence of compensatory behaviours.

Episodes are marked by feelings of lack of control.

Body weight may be maintained at normal, overweight or obese.

Anorexia nervosa

low body weight due to restriction of food intake

intense fear of gaining weight

compensatory behaviour which interferes with weight gain

Atypical eating disorders

Closely resemble anorexia nervosa, bulimia nervosa, and/or binge eating, but do not meet the precise diagnostic criteria.

Prevalence

Point prevalence of eating disorders to be 4.6% in America, 2.2% in Europe, and 3.5% in Asia.

90% of whom are female.

Risk in young men and women is highest between 13 and 17 years of age.

1. Atypical eating disorders are most common

2. Binge eating disorders

3. Bulimia nervosa

4. Anorexia nervosa is the least common.

Complications

• Psychological disturbance — anxiety and mood symptoms.

• Social difficulties — disrupted relationships and isolation.

• Family/carer stress.

• Physical abnormalities

Cardiovascular — arrhythmias, sudden death.

Musculoskeletal — loss of bone density (may be irreversible), fractures, loss of muscle strength

Endocrine — thyroid abnormalities, faltering growth or delayed puberty, impaired temperature regulation.

Gastrointestinal (GI) —enlargement of the parotid glands, knuckle calluses from inducing vomiting (Russell's sign).

Haematological — low white blood cell count (particularly neutrophils), anaemia (rarely), thrombocytopenia.

Metabolic — dehydration, electrolyte disturbance in those who misuse laxatives or diuretics or induce vomiting, re-feeding syndrome (a complication of rapid re-feeding treatment), hypothermia,

Dental — erosion of tooth enamel from vomiting.

Dermatological — dry skin, alopecia, lanugo (fine, white hairs on the body) hair

Obstetric and gynaecological — infertility (may be irreversible), amenorrhoea, risk of polycystic ovaries.

Mortality — Most due to starvation (especially cardiac and severe infection) however, 20% are due to suicide.

Investigations in primary care

Full blood count — may show anaemia from malnutrition or gastrointestinal losses, or mild leucopenia or thrombocytopenia from malnutrition.

Erythrocyte sedimentation rate (ESR) — usually normal in people with anorexia, a raised ESR may indicate an organic cause of weight loss.

Urea and electrolytes — hypokalaemia is suggestive of vomiting or laxative abuse; hyponatraemia may be a result of excess water intake.
Electrolytes may be elevated due to dehydration.

Liver function tests — may be slightly elevated from malnutrition.

Blood glucose.

Calcium, magnesium, phosphate.

B12, folate and ferritin.

Thyroid function tests.

Follicle stimulating hormone, luteinising hormone, oestradiol, prolactin and urinalysis (including pregnancy test) may be considered if presenting with amenorrhoea.

urine pregnancy test

Creatinine, and urinalysis — chronic hypokalaemia and chronic volume depletion can lead to the development of kidney disease.

Electrocardiography (ECG)

Psychiatric differential diagnosis

• Depression.

• Anxiety.

• Obsessive-compulsive disorder.

• Body dysmorphic disorder.

• Substance misuse.

• Psychosis or schizophrenia.

Management in primary care

1. Considering the need for emergency admission

   BMI: low risk 15–17.5 ; medium risk 13–15; high risk <13
   muscle power
   blood tests
   electrocardiography (ECG)

   cardiovascular instability, hypothermia, reduced muscle power, concurrent infection, overall ill health or abnormal blood tests.

2. Refer all cases to an age appropriate specialist eating disorders units (SEDUs)

   Do not use watchful waiting as a strategy for managing eating disorders

3. The SCOFF questionnaire — two or more positive answers to the following questions are suggestive of anorexia nervosa or bulimia nervosa.

   'Do you ever make yourself sick because you feel uncomfortably full?'

   'Do you worry that you have lost control over how much you eat?'

   'Have you recently lost more than one stone in a 3-month period?'

   'Do you believe yourself to be fat when others say you are too thin?'

   'Would you say that food dominates your life?'

4. While awaiting specialist assessment: Arrange regular review

5. Risk assessment
   Acute mental health risk (such as risk of suicide attempt or serious self-harm)

   Risk of refeeding syndrome:
   Risk is increased by rapid weight loss, fasting for over five days, BMI less than 16kg/m2, compensatory behaviours (such as laxative misuse or vomiting), dehydration, use of diet pills or diuretics, water loading or excessive exercise.

   Lack of support at home: