Bulimia nervosa
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
Eating disorder not otherwise specified (EDNOS)
Anorexia nervosa, binge-eating/purging subtype
Binge-eating disorder
Kleine-Levin syndrome
Other psychiatric disorders, including borderline personality disorder
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.
Management
a) 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) surgical
n/a
Prognosis
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