Definition - Disease characterised by:
- recurrent episodes of binge eating
- behaviours aimed at compensating for the binge
- Binge-eating episodes are characterised by:
- eating an amount of food that is definitely larger than most people would eat
- at least twice the normal amount of food ingested
- over a discrete period of time
- it must be ingested more quickly than normally
- Binges are accompanied by a sense of lack of control over eating during the episode
- Recurrent inappropriate compensatory behaviours occur in order to prevent weight gain
- Self-induced vomiting
- Fasting
- Excessive exercise
- Misuse of laxatives, diuretics, enemas, or other medication
- Binge-eating episodes typically occur, on average, at least twice-weekly for 3 months
Risk Factors - Female sex
- 90% of patients are female
- Personality disorder
- Association reported between negative emotionality, perfectionism, drive for thinness, poor interoceptive (body stimuli) awareness, a perception of ineffectiveness in one's life, and obsessive-compulsive personality traits.
- OCD predicts a poorer outcome if it is not treated
- Histrionic personality traits and self-directedness predict a more favourable course and/or outcome
- Body-image dissatisfaction
- Common in those with bulimia nervosa, as well as in the mothers of people with bulimia
- Body-image dissatisfaction is often reduced after improvement in bulimia nervosa
- Hx of sexual abuse
- Sexual abuse before puberty can cause severe body image dissatisfaction and increase the risk of bulimia nervosa
- However, about one third of women have a history of sexual abuse
- Impulsivity
- Impulsivity and self-injurious behaviour are increased in bulimia nervosa according to cross-sectional studies
- Cause and effect are unclear
- FHx alcoholism
- Alcoholism is more common in the family history of those with bulimia nervosa than in those with anorexia nervosa
- Alcoholism may be a marker for other psychiatric or social abnormalities
- FHx depression
- Depressive symptomatology is common in bulimia nervosa
- Major depressive disorder can worsen the course of bulimia
- FHx eating disorder
- Excessive concern about weight and shape is common in such families
- Childhood overweight or obesity
- Being obese or overweight in childhood increases the risk of bulimia nervosa
- Exposure to media pressure
- Idealisation of body shape and eating has a strong effect on the development of bulimia nervosa
- Early onset of puberty
- Early onset of puberty is associated with early onset of bulimia nervosa
- Urbanisation
- Bulimia nervosa is more common in urban areas, as are schizophrenia and depression
- By contrast, prevalence of anorexia nervosa is no different in rural and urban areas
- Bulimia is highly related to societal and cultural pressures
- Anorexia is more likely to depend on specific genetic predisposition and triggered by weight loss
- FHx obesity
- Weak predictor of bulimia.
Differential diagnosis Epidemiology - Prevalence varies worldwide
- For example, lifetime prevalence in women in Australia is 2.9%
- Lifetime prevalence estimates of DSM-IV-defined bulimia nervosa in the US are 1.5% in women and 0.5% in men
- Higher lifetime prevalence has been found in white women than in black women
- This range of prevalence may reflect imperfect case-finding or differences in populations
Aetiology - The aetiology of bulimia nervosa is uncertain
- A biopsychosocial theory of causation posits a combination of coexisting biological (genetic abnormalities in receptors or neurotransmitters), psychological, and social factors
- Risk factors that are strongly associated with bulimia nervosa include:
- female sex
- perfectionism
- body dissatisfaction
- impulsivity
- history of sexual abuse
- family history of alcoholism, depression, or eating disorder
- past obesity
- exposure to media pressure
- An association with urbanisation has been reported
- Family history of obesity is considered a weak predictor of bulimia
- Early onset of puberty is associated with early onset of bulimia nervosa
Clinical features - Recurrent episodes of binge eating
- Necessary for diagnosis.
- Binge eating must:
- occur within a discrete period of time (e.g., 2 hours)
- involve an amount of food that is definitely larger than most people would eat during a similar period of time and under similar circumstances
- A sense of lack of control must be present during the episode
- e.g., a feeling that one cannot stop eating or control what or how much one is eating
- Occurs, on average, at least twice a week for 3 months
- Recurrent inappropriate compensatory behaviour
- There must always be some form of compensatory behaviour to attempt to burn off calories
- This may be:
- purging (vomiting, laxatives, enemas, suppositories)
- non-purging (exercise, fasting).
- Occurs, on average, at least twice a week for 3 months
- Eating disturbance not exclusively during periods of anorexia nervosa
- Confirmation of an eating disturbance that does not occur during periods of anorexia nervosa is a diagnostic requirement in DSM-IV
- Depression and low self-esteem
- Patients usually have low self-esteem, lack of confidence, and depressive thoughts
- Treatment of concurrent depression improves outcome
- Concurrent depression may be related to drug or alcohol abuse
- Should be monitored and addressed in treatment
- Concern about weight and body shape
- Nearly always present, although it may be denied initially
- Self-evaluation is unduly influenced by body shape and weight
- Dental erosion
- Erosion of adult teeth is permanent and can be extremely costly to correct
- Dental changes often reduce self-esteem and can make it painful and difficult to chew hot or cold food.
- It is important to prevent and treat dental erosion.
- Better appearance is also a motivational tool.
- Focusing on the changes in gums and teeth that point to a progression of tooth loss can motivate patients to accept treatment
- Parotid hypertrophy
- The parotid glands are bilaterally enlarged but are usually not tender unless the purging is frequent
- Russell's sign
- Scarring over the dorsum of the hands.
- This results from pressing fingers against the teeth inserted into the mouth to induce vomiting
- Arrhythmia
- More common in presence of hypokalaemia or hypomagnesaemia.
- Loss of consciousness, fainting, ventricular arrhythmias, and arrhythmias lasting more than a few minutes are rare.
- Menstrual irregularity
- Occasional missed or abnormal menstrual periods can occur.
- Important for counselling, particularly because contraceptive pills may be purged.
- A skipped period may be due to pregnancy or to the bulimia itself
- This contrasts with anorexia nervosa, where menstrual irregularity is a required component of the disease
- Drug-seeking behaviour
- Physicians should be aware that abuse of laxatives and drug-seeking behaviour for laxatives and appetite suppressants is common.
- In addition, medications may be collected to use for suicide
- Deliberate misuse of insulin
- Patients with diabetes may skip insulin to control their weight.
- This leads to marked fluctuations in blood sugar and rapid onset of diabetic microvascular complications
- Self-injurious behaviour
- Patients will usually not mention such behaviour.
- Therefore, their skin should be examined
- GI symptoms
- Oesophageal reflux, diarrhoea, constipation, and abdominal pain are frequent in bulimia nervosa.
- These result from volume depletion and deficiencies of vitamins and minerals arising from bingeing on large volumes of food, with erratic eating in between vomiting
- Hx of dieting
- Patients with bulimia nervosa are often ashamed to admit they have the disease.
- Therefore, a high index of suspicion is important.
- A history of dieting would raise suspicion for the condition
- Marked fluctuations in weight
- A history of dieting along with a high index of suspicion would raise the possibility of the condition
- Needle marks on skin
- Patients may self-phlebotomise as a form of purging, but rarely give this history.
- Anaemia and the presence of needle marks may be the only clues
Pathophysiology - The pathophysiology of bulimia nervosa is unknown
- However, evidence suggests that people may binge and purge when:
- they have low self-esteem
- when they are pressured to conform to eating or to adhere to a specific weight and shape
- when they are knowledgeable about bingeing and purging
- Compensatory behaviours such as vomiting, use of laxatives, or exercise may result in large fluctuations in weight that reinforce the behaviour
- These behaviours can result in:
- erosion of the teeth
- parotid and submandibular gland hypertrophy
- oesophageal reflux, dysmotility, or spasm
- gastric dysmotility
- bowel irregularity
- volume depletion
- cardiac arrhythmia
- metabolic abnormalities such as hypokalaemia or hypomagnesaemia
Investigations- Serum electrolytes
- Hypokalaemia may be accompanied by other electrolyte disorders for which there are no ready explanations.
- Elevated serum bicarbonate in bulimia nervosa usually indicates an alkalosis due to emesis of gastric acid
- Electrolytes must be combined with ABG measurement to definitively diagnose an acid-base abnormality
- Serum creatinine
- May reflect azotaemia due to volume depletion
- Serum magnesium
- Total body magnesium depletion frequently occurs with normal serum magnesium levels
- If serum magnesium is low, the total body levels are always low.
- Serum magnesium should be ordered separately from serum electrolytes
- Urine pregnancy test
- The possibility of pregnancy should always be considered with a change in symptoms
- Serum LFTs
- Drug overdose, alcohol ingestion, or excess exercise may elevate aminotransferases
- Serum creatine kinase
- Drug overdose, alcohol ingestion, or excess exercise may elevate CK
- FBC
- Patients may self-phlebotomise as a form of purging, but rarely give this history.
- Anaemia and the presence of needle marks may be the only clues
- Urinalysis
- Patients with comorbid diabetes mellitus may have poor glycaemic control.
- Some patients may skip insulin to control their weight
- ECG
- If there is a deficiency of potassium or magnesium, or a history of anorexia nervosa, there can be a prolonged QTc interval or arrhythmias
- If the QTc is >440 milliseconds, or rhythm or conduction is abnormal, urgent evaluation is required.
- Serum ferritin
- To evaluate presenting symptoms such as menstrual irregularity or abdominal symptoms
- Ferritin may be low, reflecting low iron levels.
- Serum B12
- Nutritional deficiencies including B12 (or, rarely, thiamine, niacin, copper, and riboflavin) may be present
- Bulimia should be considered in a young woman who presents with such a deficiency.
- Serum RBC folate
- May be seen in nutritional folate deficiency.
- DEXA scan for bone density
- Commonly normal unless there is a prior history of anorexia nervosa.
- Bone density is often decreased in anorexia nervosa.
- Low bone density
correlates with low total body fat and amenorrhoea, neither of which is
common in bulimia nervosa.
Managementa) conservative- cognitive behavioural therapy (CBT)
- nutritional and meal support
- other types of supportive psychological therapy
b) medical - glycaemic control
- SSRI or serotonin-norepinephrine reuptake inhibitor (SNRI)
c) surgicalPrognosis- Bulimia nervosa has an average onset at an age of about 18 years
- However bingeing and purging to a lesser degree is much more common
- Many, if not most patients, who meet the diagnostic criteria for bulimia do not access medical help.
- Of those who do:
- 45% to 75% recover completely
- 27% improve considerably
- 23% have a chronic course
- The crude mortality rate is approximately 0.32% to 3.9%
- Most patients with bulimia nervosa continue an active life despite the disorder
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