The most important factor in the identification of eating disorders in generalist settings is for the practitioner to consider the possibility of an eating disorder and to be prepared to inquire further in an empathic and non-judgmental manner. The history is paramount and special investigations are not normally required to make a diagnosis.
5.2.4.1. Anorexia nervosa
The first contact with health care services is often made by a worried family member, friend or schoolteacher rather than the patient. Concerns expressed may be related to weight loss, food-related behaviours such as skipping meals, hiding food or adopting a restrictive diet. There may be a change in mood, sleep patterns and increased activity. Typical psychopathological features are fear of gaining weight or becoming fat despite being underweight, disturbance in evaluating or experiencing body weight or shape, undue influence of eating or changes in body weight on self-evaluation and preoccupation with shape or weight-related matters. These features may not all be present, easy to elicit or they may be denied. However, denial of the seriousness of the weight loss or consequences, both physical and psychological is usually present.
Established anorexia nervosa with signs of emaciation is usually obvious. However, patients may present initially in primary care with non-specific physical symptoms such as abdominal pain, bloating, constipation, cold intolerance, light headedness, hair, nail or skin changes. Amenorrhoea, combined with unexplained weight loss, in the population at risk should always prompt further enquiry. Apparent food allergy/intolerance and chronic fatigue syndrome sometimes precede the development of an eating disorder and may cause diagnostic confusion. In children, growth failure may be a presenting feature.
In practice, typical cases should cause little difficulty when the time is taken to explore the history including corroborative information and the patient’s attitude to the weight loss. Indeed, diagnosis is often delayed when doctors inadvertently collude by over-investigating and referring to other specialties rather than confronting the possibility of an eating disorder.
Diagnostic criteria
These are outlined in the introduction (see Section 2.1.2).
In children and adolescents under 18, the use of BMI centile charts should be encouraged (Cole, Bellizi et al., 2000) with a cut off less than the 2.4th centile of the reference population indicating underweight.
Centile charts for weight and height are also helpful in showing failure to progress over time.
The list of potential differential diagnoses of weight loss or amenorrhoea is large, but in practice, typical cases should cause little difficulty when the time is taken to explore the history including corroborative information and the patient’s attitude to the weight loss. The following factors need to be considered:
Risk factors – family history of eating disorder, Type 1 diabetes, previously overweight, occupation (e.g. athlete, dancer, model). Although adolescent girls and young women constitute the principal population at risk, it should be remembered that eating disorders also occur in ethnic minorities, men and children.
Differential diagnosis of weight loss – includes malabsorbtion (e.g. coeliac disease, inflammatory bowel disease), neoplasm, illicit drug use, infection (e.g. TB), autoimmune disease, endocrine disorders (e.g. hyperthyroidism).
Differential diagnosis of amenorrhoea – includes pregnancy, primary ovarian failure, poly cystic ovary syndrome, pituitary prolactinoma, uterine problems and other hypothalmic causes.
Psychiatric differential diagnosis – includes depression, obsessive-compulsive disorder, somatisation and, rarely, psychosis.
Initial physical assessment
The rationale for physical assessment is more to determine the presence and severity of emaciation and secondary physical consequences of the anorexia nervosa than to ascertain the primary diagnosis.
It should include as a minimum:
The following may also be helpful to assess the risk of physical instability:
Core temperature (this is easily done by ear thermometer)
Examination of peripheries (circulation and oedema)
Cardiovascular examination including postural hypotension
Laboratory investigations
Extensive laboratory investigation is not usually required in the diagnosis or assessment of anorexia nervosa in a primary care setting. Many tests remain normal even with extreme weight loss and are a poor guide to physical risk. The diagnosis is always made on the basis of the clinical history.
Investigations
The following would represent a reasonable initial screen in primary care if there are no other indications or diagnostic concerns:
Full Blood Count, ESR, Urea and Electrolytes, Creatinine, Liver Function Tests, Random Blood Glucose, Urinalysis.
ECG: This should be considered in all cases and is essential if symptoms/signs of cardiac compromise, bradycardia, electrolyte abnormality or BMI less than 15 kg/m2. (Or equivalent on centile chart.)
Further tests may be required in more severe cases or to assess complications: Calcium, Magnesium, Phosphate, Serum Proteins, Creatine Kinase (CK or CPK).
Tests that may be needed in the differential diagnosis of amenorrhoea and weight loss:
Thyroid Function Tests, Follicle Stimulating Hormone, Lutenising Hormone, Prolactin, Chest X-Ray.
A DXA scan may be considered for identification of osteopenia/osteoporosis, which may occur after six to 12 months of amenorrhoea. Although this is not necessarily a primary care level investigation, it has been suggested that it may be helpful in encouraging motivation for change in those not yet ready to accept referral, by demonstrating the real physical consequences of anorexia nervosa.
5.2.4.2. Bulimia nervosa
Identification
The patient with bulimia nervosa is more likely to be older and to consult alone than a patient with anorexia nervosa. There may be a history of previous anorexia nervosa or of unhappiness with previous weight and attempts to diet. Appropriate questioning (see screening section above) may reveal patterns of restriction, binge eating and purging and psychopathology that make the diagnosis clear. Not infrequently, physical symptoms are presented which may be related to or consequences of purging or laxative use. These symptoms, particularly in a young woman should be a ‘red flag’ in prompting the practitioner to consider further enquiry.
Where the patient does not disclose bulimia nervosa, a range of symptoms may present which should raise the index of suspicion. These include requests for help with weight loss, menstrual disturbance and the physical consequences of vomiting and laxative and diuretic use. Non-specific symptoms may include fatigue, lethargy. Gastrointestinal disorders may be present including bloating, fullness, abdominal pain, irritable bowel syndrome type symptoms, constipation, diarrhoea and rectal prolapse as well as oesophagitis and gastrointestinal bleeding. Oropharyngeal symptoms may include a sore throat, parotid swelling and dental enamel erosion.
Physical examination and investigation
In bulimia nervosa and related conditions, characteristic physical signs have been described (for example, parotid enlargement, Russell’s sign (callus formation on the dorsum of the hand) and dental enamel erosion, which are usually manifestations of purging. In practice these are not seen in the majority of patients presenting in primary care with bulimic disorders, although electrolyte abnormalities are reasonably common, so urea and electrolytes should be routinely obtained. These are covered in Section 7.5.2.
