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