Anorexia Nervosa Flashcards
What is anorexia nervosa (AN)?
Anorexia nervosa (AN) is an eating disorder characterized by deliberate weight loss, an intense fear of fatness, distorted body image and endocrine disturbances.
What are the predisposing factors for AN?
Note: biological, psychological and social
Biological
- Genetics: monozygotic twin studies have higher concordance rates than dizygotic twins
- Family history: first degree relatives have higher incidence of eating disorders
- Female
- Early menarche
Psychological
- Sexual abuse
- Preoccupation with slimness
- Dieting behaviours starting in adolescence
- Low self-esteem
- Premorbid anxiety or depressive disorder
- Perfectionism and obsessional/ anankastic personality
Social
- Western society: pressure to diet in a society that emphasises that being thin is beauty
- Bullying at school revolving around weight
- Stressful life events
What are the precipitating factors for AN?
Note: biological, psychological and social
Biological
- Adolescence and puberty
Psychological
- Criticism regarding eating, body shape or weight
Social
- Occupational or recreational pressure to be slim, e.g. ballet dancers and models
What are the perpetuating factors for AN?
Note: biological, psychological and social
Biological
- Starvation leads to neuroendocrine changes that perpetuate anorexia
Psychological
- Perfectionism and obsessional/ anankastic personality.
Social
- Occupation
- Western society
Is AN more common in men or women?
AN affects ♀ more than ♂ ( 10:1 ).
Estimated incidence is 0.4 per 1000 yearly in ♂ and approximately 9 in 1000 ♀ will experience it at some point in their lives.
What is the typical age of onset of AN?
The typical age of onset is mid-adolescence.
Briefly describe the ICD-10 Criteria for diagnosing AN
Note: FEED
- Fear of weight gain
- Endocrine disturbance resulting in amenorrhoea in females and loss of sexual interest and potency in males
- Emaciated (abnormally low body weight):
- >15% below expected weight or BMI <17.5 kg/m2
- Deliberate weight loss with ↓ food intake or ↑ exercise
- Distorted body image
Note: the above features must be present for at least 3 months and there must be the absence of recurrent episodes of binge eating and preoccupation with eating/craving to eat.
What other features are present in AN?
Note: PPSS
- Physical: fatigue, hypothermia, bradycardia, arrhythmias, peripheral oedema (due to hypoalbuminaemia), headaches and lanugo hair
- Preoccupation with food: dieting, preparing elaborate meals for others
- Socially isolated
- Sexuality feared
- Symptoms of depression and obsessions
Briefly describe how to calculate BMI and the values for underweight, normal, overweight and obese
Body mass index = weight (kg) ÷ [height (m)]2
- BMI <18.5 kg/m2 = underweight
- BMI 18.5– 24.9 kg/m2 = normal
- BMI 25– 29.9 kg/m2 = overweight
- BMI ≥30 kg/m2 = obese
Briefly differentiate between AN and bulimia nervosa
Anorexia nervosa
- Are significantly underweight
- Are more likely to have endocrine abnormalities such as amenorrhoea
- Do not have strong cravings for food
- Do not binge eat
- May have compensatory weight loss behaviours (excluding purging)
Bulimia nervosa
- Are usually normal weight/overweight
- Are less likely to have endocrine abnormalities
- Have strong cravings for food
- Have recurrent episodes of binge eating
- Have compensatory weight loss behaviours
Briefly describe the MSE for AN
Appearance and Behaviour: thin, weak, slow, anxious. May try to disguise emaciation with makeup and appear with dry skin and lanugo hair. Baggy clothes.
Speech: may be slow, slurred or normal.
Mood: can be low with co-morbid depression or euthymic.
Thought: preoccupation with food, overvalued ideas about weight and appearance.
Perception: no hallucinations.
Cognition: either normal or poor if physically unwell with complications.
Insight: often poor.
What investigations should be ordered for AN?
Blood tests:
- FBC (anaemia, thrombocytopenia, leukopenia)
- U&Es ( ↑ urea and creatinine if dehydrated, ↓ potassium, phosphate, magnesium and chloride)
- TFTs ( ↓ T 3 and T 4 )
- LFTs ( ↓ albumin)
- Lipids ( ↑ cholesterol)
- Cortisol ( ↑ )
- Sex hormones ( ↓ LH, FSH, oestrogens and progestogens)
- Glucose ( ↓ )
- Amylase (pancreatitis is a complication)
Venous blood gas (VBG): metabolic alkalosis (vomiting), metabolic acidosis (laxatives).
DEXA scan: to rule out osteoporosis (if suspected).
ECG: arrhythmias such as sinus bradycardia and prolonged QT are associated with AN patients.
Questionnaires: e.g. eating attitudes test (EAT).
What are the metabolic complications of AN?
- Hypokalaemia
- Hypercholesterolaemia
- Hypoglycaemia
- Impaired glucose tolerance
- Deranged LFTs
- ↑ urea and creatinine (if dehydrated)
- ↓ potassium
- ↓ phosphate
- ↓ magnesium
- ↓ albumin
- ↓ chloride
What are the endocrine complications of AN?
- ↑ cortisol
- ↑ growth hormone
- ↓ T3 and T4
- ↓ LH, FSH, oestrogens and progestogens leading to amenorrhoea
- ↓ testosterone in men
What are the GI complications of AN?
- Enlarged salivary glands
- Pancreatitis
- Constipation
- Peptic ulcers
- Hepatitis
What are the cardiovascular complications of AN?
- Cardiac failure
- ECG abnormalities
- Arrhythmias
- ↓ BP
- Bradycardia
- Peripheral oedema
What are the renal complciations of AN?
- Renal failure
- Renal stones
What are the neurological complications of AN?
- Seizures
- Peripheral neuropathy
- Autonomic dysfunction
What are the haematological complciations of AN?
- Iron deficiency anaemia
- Thrombocytopenia
- Leucopenia
What are the MSK complications of AN?
- Proximal myopathy
- Osteoporosis
What are the ‘other’ important complications of AN?
- Hypothermia
- Dry skin
- Brittle nails
- Lanugo hair
- Infections
- Suicide
What is bulimia nervosa?
Recurrent episodes of binge eating and compensatory behaviour (any one or a combination of vomiting, fasting, or excessive exercise) in order to prevent weight gain.
What is binge eating disorder?
Recurrent episodes of binge eating without compensatory behaviour such as vomiting, fasting, or excessive exercise.
What is EDNOS or atypical eating disorder?
One third of patients referred for eating disorders have EDNOS (eating disorders not otherwise specified). EDNOS closely resembles anorexia nervosa, bulimia nervosa, and/or binge eating, but does not meet the precise diagnostic criteria.
Briefly describe the bio-psychosocial approach to treating AN
Biological
- Treatment of medical complications e.g. electrolyte disturbance
- SSRI s for co-morbid depression or OCD
Psychological
- Psycho-education about nutrition
- Cognitive behavioural therapy
- Cognitive analytic therapy
- Interpersonal psychotherapy
- Family therapy
Social
- Voluntary organisations
- Self-help groups
How long should psychological input be for?
Psychological treatments should normally be for at least 6 months’ duration.
What kg/ week should we aim to increase weight for in AN patients?
Note: inpatient and outpatient
The aim of treatment as an inpatient is for a weight gain of 0.5– 1 kg/week and as an outpatient of 0.5 kg/week .
When is hospitalisation for AN required?
Hospitalisation is necessary for medical (severe anorexia with BMI <14 or severe electrolyte abnormalities) and psychiatric (suicidal ideation) reasons.
What is the main risk of treating AN?
Patients are at risk of refeeding syndrome which causes metabolic disturbances (e.g. ↓ phosphate) and other complications.
What is refeeding syndrome?
A potentially life-threatening syndrome that results from food intake (whether parenteral or enteral) after prolonged starvation or malnourishment, due to changes in phosphate, magnesium and potassium.
It occurs as a result of an insulin surge following increased food intake.
Biochemical features include fluid balance abnormalities, hypokalaemia, hypomagnesaemia, hypophosphataemia and abnormal glucose metabolism.
The phosphate depletion causes reduction in cardiac muscle activity which can lead to cardiac failure .
How is refeeding syndrome treated and prevented?
If electrolyte levels are low, they will need to be replaced either orally or intravenously depending upon the severity of electrolyte depletion.
Prevention: measure serum electrolytes prior to feeding and monitor refeeding bloods daily, start at 1200 kcal/day and gradually increase every 5 days, monitor for signs such as tachycardia and oedema.
What differentials should be considered for AN?
- Bulimia nervosa
- Eating disorder not otherwise specified (EDNOS)
- Depression
- Obsessive- compulsive disorder
- Schizophrenia
- Delusions about food
- Organic causes of low weight:
- Diabetes
- Hyperthyroidism
- Malignancy
- Alcohol or substance misuse
