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)

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