Investigations

• gonadotrophins - low FSH, LH
• prolactin reduced during sleep but normal day time levels
• T3 - low; but do not treat for hypothyroidism as the low level is secondary to low body weight
• T4, TSH - normal
• growth hormone - raised, secondary to reduced carbohydrate intake
• cortisol levels are high-normal or supranormal
• ESR - normal or low; an elevated ESR is suggestive of organic disease
• other tests include full blood count, urinalysis, creatinine levels, liver function tests, and random blood glucose
• Electrolyte disturbance may be present in those who are believed to be engaging in compensatory behaviours, such as vomiting, taking laxatives or diuretics, or water loading. Metabolic imbalances such as hypokalaemia should be excluded.
• assess whether ECG monitoring is needed in people with an eating disorder, based on the following risk factors:
  • rapid weight loss
  • excessive exercise
  • severe purging behaviours, such as laxative or diuretic use or vomiting
  • bradycardia
  • hypotension
  • excessive caffeine (including from energy drinks)
  • prescribed or non-prescribed medications
  • muscular weakness
  • electrolyte imbalance
  • previous abnormal heart rhythm.

Note: a reduction in bone mass is an important complication of anorexia nervosa and the guidance regarding assessment is linked.

Reference:

• (1) NICE (May 2017). Eating disorders: recognition and treatment
• (2) Prescribers' Journal (1999), 39 (4), 227-233.