Definition - Eating disorder characterised by:
- low body weight (<85% ideal body weight)
- disturbed body image
- dietary practices to maintain low weight
- fear of gaining weight
- lack of menstrual periods for ≥3 months
- Frequent exercise is common
Risk Factors - Female gender
- About 70% of AN patients are female
- But 90% of patients seen are likely to be female due to reduced presetation in males
- Pressures to achieve cultural ideals of beauty are placed primarily on women, less so on men
- Anorexia in males may be under-reported.
- Adolescence and puberty
- Onset peaks at ages 14.5 and 18 years
- 5-fold incidence in the teenage versus older female population
- Onset in women in their 20s and 30s is increasing, indicating a possible trend change
- Obsessive and perfectionist traits
- Strongly linked to condition in case-study research
- Non-specific risk for developing both anorexia and bulimia
- Exposure to western media
- Disease prevalence in West is 0.1% to 5.7% in females
- Culture-change syndrome
- Immigrants moving to western-influenced cultures exhibit a higher incidence
- Middle and upper socioeconomic classes
- Linked with increased risk of eating disorders with the exception of binge eating disorder
- Pressures to achieve success in the eyes of society increase with status
- Identical twin affected
- Studies showed a 6.6% risk of an identical female twin developing disease
- Fraternal twins show no increased risk, leading to conclusion that the link is biological
- Family dysfunction
- Family dysfunction influences psychological makeup of anorexics and is potentially involved in the condition's development
Differential diagnosis - Bulimia nervosa
- Complain of bloating, abdominal pain, sore throat, and a feeling of fullness.
- Depression
- Often show poor concentration and poor self-esteem, not solely linked to weight gain or loss.
- Hyperthyroidism
- Weight loss with additional symptoms of heat intolerance, hyperactivity, polyuria, sweating, nausea with vomiting, diarrhoea, and tremors.
- Type 1 diabetes mellitus
- History of blurred vision, polyuria, polydipsia, and polyphagia are common with weight loss, but without purging.
- Crohn's disease
- May have abdominal pain, bloody stools, and possibly arthritic pain in addition to weight loss
- Patients do not avoid food for fear of gaining weight.
- Colonoscopy with biopsy will show inflammatory tissue changes.
- Ulcerative colitis
- May have abdominal pain, bloody stools, and possibly arthritic pain in addition to weight loss.
- Colonoscopy with biopsy will show inflammatory tissue changes.
- Obsessive-compulsive disorder (OCD)
- OCD often presents similarly, with ritualised eating habits.
- However, OCD is characterised by obsessions unrelated to food, such as a fear of death.
- Medication may be effective, unlike in anorexia
- Cancer (any type)
- Weight loss unintentional without fear of weight gain or body image disruption.
- FBC may show anaemia.
- If warranted, biopsy, cytology, and imaging should be carried out.
- HIV infection
- May have a history of fever, headache, aching muscles, sore throat, and often swollen lymph nodes, mouth and oesophageal ulcers, and rash in addition to weight loss.
Epidemiology - About 0.3% of people in westernised countries, with about 0.5% to 1% of college-aged women, are affected
- It is estimated that 3 in 10 patients are male
- Many males do not present for treatment
- Thus, about 90% of patients diagnosed are female
- The incidence of homosexuality among anorexic men is 25% to 58%, depending on the study.
- The risk of onset is highest in late adolescence, with 40% of new cases found between ages 15 and 19 years
- Only one third seek medical care
- Patients show a 25% lifetime prevalence of concomitant OCD and a 50% to 70% prevalence of dysthymia
- White women are more likely to develop anorexia than black women
- Multiple cross-cultural studies have linked increases in eating disorders to western media exposure and ideals
Aetiology - The specific cause is unknown at present
- Several neurotransmitters have been implicated in the aetiology of AN
- However studies have been generally difficult to interpret
- Changes seen may be a consequence of semi-starvation, rather than the cause of semi-starvation
- Evidence suggests that genetic factors are important in the development of AN
- Heritability estimates range from 50% to 75% using a wide variety of assessment strategies
Clinical features - Weight loss
- <85% of normal weight for height and age.
- BMI is usually <17.5 kg/m^2
- Fear of gaining weight
- Avoids and refuses intervention to gain weight
- Disturbed body image
- Indicates either abnormally large size of certain body parts or failure to acknowledge overall thinness
- Calorie restriction
- In restrictive type, calorie intake is lowered to 300 to 700 kcal a day
- Bingeing and/or purging
- May exist as part of bingeing and/or purging subtype
- May conceal this detail in history
- Physical signs of dental erosion and hand calluses must be relied upon
- Misuse of laxatives, enemas, and/or diuretics
- Part of bingeing and/or purging subtype
- Amenorrhoea
- Whether patient is taking oral contraceptives should be determined
- Decreased subcutaneous fat
- Bony structures may protrude due to the extreme lack of body fat
- Fatigue and weakness
- Specifically related to weight loss
- Poor concentration
- Specifically related to weight loss
- Fainting
- Often related to orthostatic hypotension and bradycardia
- Constipation
- Due to a decrease in gastrointestinal motility related to decreased consumption of calories
- Lanugo body hair
- Development of fine body hair
- Orthostatic hypotension
- Low fluid status may result in slow re-equilibration from sitting to standing
- May result from hypovolaemia and/or low cardiac output
- Bradycardia
- Due to an adaptive response to weight loss and negative energy balance
- Dehydration
- Due to an inadequate intake of fluids
- Cardiac arrhythmias
- May be due to a decreased heart size as a result of weight loss
- Hair loss
- Occurs due to inadequate nutrition
- Shorter stature
- A sign of poor growth and nutrition in adolescents
- Hypothermia
- Eroded dental enamel
- Sign of bingeing and/or purging
- May be associated dental abscesses or caries
- Scars on dorsum of hand
- Repetitive forcing of the hand down back of the throat may cause scars
- Dependent oedema
- May be due to low protein stores, resulting in fluid shift
- Increased fractures
- More common in affected people in their 20s
Pathophysiology - The pathophysiology is currently unknown
- A susceptible person, whether through biology, societal patterns, or behavioural makeup, begins dieting
- 35% of those dieting progress to pathological eating habits
- 20% to 25% go on to partial or full-blown eating disorders
- Weight loss gives positive reinforcement to continue avoidance of food, intense exercise, or bingeing and/or purging behaviours
- The effect of low weight and starvation leads to nutritional imbalances and psychological changes
- Due to the patient's tendency towards obsessive behaviours and rigid thought patterns, the patient maintains the anorexic cycle
- The act of starvation and weight loss may provide a sense of pride and positive drive for the patient
- Any life stresses, often interpersonal in nature, are avoided with the obsessive focus on food and weight management
- A sense of controllable satisfaction and success prompts continuation
- The patient gains confidence and resists walking away from the safety of routine
- Psychologically speaking, AN relieves generalised anxiety, which takes the form of an easy-to-identify fear of food
- The fear of gaining weight leads to avoidance of food, which leads to relief of anxiety through weight loss
- Additionally, physiological changes propagate the disease and continual relapses
- Corticotrophin-releasing hormone, released during starvation
- Promotes appetite suppression
- Also increases cortisol levels, which in turn increases the risk for osteoporosis
- Vasopressin is high and oxytocin low in cerebrospinal fluid
- Hypothesised to promote the unhealthy thought patterns
Investigations- FBC
- normocytic normochromic anaemia
- mild leukopenia
- thrombocytopenia
- Serum chemistry
- metabolic alkalosis and hypokalaemia (vomiting)
- metabolic acidosis, hyponatraemia and hypokalaemia (laxatives)
- hypomagnesaemia
- hypophosphataemia
- hypocalcaemia
- hypoglycaemia
- elevated urea levels
- TFTs
- T3 low, T4 normal, TSH normal
- LFTs
- elevated ALT
- elevated AST
- decreased ALP
- urinalysis
- urine pregnancy test
- to rule out pregnancy as cause for amenorrhoea
- ECG
- conduction defects
- prolongation of QT interval
- bone densitometry
- oestradiol (in females)
- testosterone (in males)
Managementa) conservative - structured eating plan with oral nutrition
- psychotherapy
- behavioural family systems therapy
- cognitive analytical therapy
- conjoint family therapy
- cognitive therapy
- dietary counselling
- educational behavioural therapy
- ego-oriented individual therapy
- focal analytical therapy
- family therapy
- interpersonal therapy
- individual therapy
- non-specific supportive clinical management
- separated family therapy
b) medical- potassium repletion
- oral, enteral or parenteral nutrition
- fluid intake correction
- magnesium repletion
- calcium repletion
- sodium repletion
- selective serotonin reuptake inhibitors (SSRIs)
c) surgical
Prognosis- In those who are 9.1 to 13.6 kg underweight, weight gain averages between 0.9 and 1.4 kg a week
- May require inpatient care for 2 to 3 months
- Relapse rates are higher for patients discharged while underweight, putting inordinate pressure on families
- Full remission can occur only when care continues as an outpatient
- Patients who are treated early in adolescence and reside with their nuclear family have a good prognosis if treated by experienced personnel
- About 70% of these patients have a full and lasting recovery
- Time to recovery is 3 to 5 years
- Older patients are prone to relapse
- Considering AN in these patients as a chronic disease can promote a more effective management.
- Long-term outcome
- After 10 to 15 years of investigation, one study showed that over 75% of patients recovered completely
- Study results showed 4 main predictors of negative long-term outcome:
- sexual problems
- impulsivity
- protracted duration of anorexia
- long inpatient treatment
- Mortality remains high at 12%
- Deaths are mainly due to suicide, or medical complications
- Anorexia has the highest mortality among psychiatric diagnoses
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