Anorexia nervosa

General paediatrics, Mental health, Nutrition

Eating disorders categorised as:

  • Anorexia Nervosa (IDC-10, DSM-IV)
  • Bulimia Nervosa (IDC-10, DSM-IV)
  • Eating Disorder not otherwise specified (EDNOS)
  • Binge Eating Disorder (without the compensatory behaviours of bulimia eg vomiting, exercise)
  • Selective/Restrictive Eating

DSM-IV Criteria for Anorexia Nervosa

  • Body weight at or below 85% of that expected
  • Fear of gaining weight or becoming fat, even though underweight
  • Disturbed perception of body weight or shape
  • Amenorrhea, at least 3 consecutive cycles
  • Disturbance in way one’s body shape is experienced (?)

ICD-10 adds a couple of things:

  • BMI < 15
  • Weight loss caused by food avoidance, self induced vomiting, purging, excessive exercise (not in DSM)
  • loss of libido in men
  • Pubertal delay if early onset

For children, these strict criteria can overlook significant disordered eating – wide variation in weight and height gain through puberty; menses not present else irregular.  Levels of cognitive development obviously vary.  Abnormal food behaviours eg slow eating, hiding may have been present from a young age. One type of eating disorder can change into another.

Interest in healthy eating and exercise may initially give impression that child is well. Dieting is miserable for most people, but for some it appears to relieve anxiety, which can lead to a vicious cycle. Sometimes it is specific foods that are feared.

BMI <2nd centile prob more useful for kids.  GOSH Criteria (Nicoles, Chater & Lask 2000) talks about determined wt loss, abnormal cognitions about weight/shape but also morbid preoccupation.  Similarly, Bulimia Nervosa defined as Recurrent binges and purges, Sense of lack of control, Morbid preoccupation with weight or shape. Purging is any behaviour to prevent weight gain including self induced vomiting, fasting, dieting, excessive exercise, misuse of medicines such as diuretics or laxatives.

Questions:

  • What did you eat yesterday? Are there foods you don’t eat any more?
  • Are you more interested in food and cooking?
  • Are you trying to cut back?
  • Does it ever feel like your eating gets out of control?
  • What happens if you can’t exercise?
  • Have you been making yourself sick? Do you drink water to prevent hunger?
  • What do you see when you look in the mirror? (Body dysmorphia = perception of shape, size that is unrelated to reality). Is there a weight you would like to be? What sort of things do you look at online?
  • Explore mood and risk of self harm.  Anhedonia (inability to enjoy anything) common. Ask direct questions about abuse or neglect (explain this is routine).

Clinical features:

  • short stature,
  • hypothermia,
  • dry lips/mouth,
  • ketosis,
  • scaphoid abdomen,
  • pallor/carotenaemia/acrocyanosis,
  • lanugo, thinning of scalp hair,
  • dry skin and brittle nails,
  • evidence of self harm,
  • Flat affect, mood changes, impaired concentration/memory,
  • hypotension, orthostatic HR/BP changes,
  • SUSS test – stand, squat, stand (without using upper limbs); sit up from lying
  • cardiac failure,
  • peripheral neuropathy.
  • Callus on back of hand (Russell’s sign) in bulimia

Associated with depression, anxiety, obsessive/compulsive disorder and alcohol misuse.

Differential

Beware diabetes, hyperthyroidism, Addison’s, coeliac, malignancy.

Treatment

Early intervention associated with better outcomes.  Poor outcome in anorexia if patient does not receive effective treatment in first 3 years. 

Principles –

  • Give diagnosis – may not be appreciated. Anosognosia = inability to see weight loss or failing health (and therefore others with that viewpoint are irrational or unkind)
  • Strengthening family relationships away from food (in many families tends to be around meals, snacks, eating out, and many conversations around favourite foods etc)
  • Conceptualising the eating problem as being separate from the young person.  Eating problem as “bullying voice”. Avoid discussions of weight or body image (“you look healthier” can be misinterpreted as “you look fat” by eating problem).
  • Not a choice, not rational. Alexithymia (inability to express feelings) common. Genetic heritability accounts for approximately 50–80% of the risk of developing an eating disorder, often pre-existing tendencies towards anxiety, inflexibility, difficulties with emotional regulation, enhanced sensitivity towards punishment. [Proposed mechanism here]
  • Families are not to blame!
  • Food is medicine. Enforcing regular, balanced meals and snacks (3 of each daily) as a family improves mood, behaviour as well as physical symptoms. Terrifying at first, of course. Metabolism often ramps up once refeeding begins, so a huge increase in intake is often required to achieve restoration of healthy weight (and catch up growth) in anorexia. For bulimia, regular pattern of eating more important.
  • Don’t allow meal choices or negotiation, discourage involvement in or observation of food preparation, which reinforces disordered thinking. Reduces anxiety when not required to make “difficult” choices about problem foods.
  • Avoid regular weighing and other forms of body checking
  • Full recovery is possible, especially when detected early eg months rather than years.

Can be helpful to offer option not to be told weight.  Beware concealing weights on body, water loading before weighing day.  Praise honesty, highlight confidentiality, agree sharing of information with parents.

Parents can become used to “new normal” of disordered eating, and might not appreciate risks.  Alternatively, young person might feel threatened by alliance between doctor and parents.

Target weight is tricky – what is required for normal bodily function? What was growth/puberty trajectory before eating restricted? So healthy thoughts about food, normal periods (often 9 months or more), return of premorbid personality etc. Fluctuating weight gain may be due to metabolism, fluid shifts, concealed weights or water loading, concealed purging (silent exercise eg crunches in bed).

Where food refusal is an issue, energy dense food is required – increase fat content, avoid water or diet drinks, leave fruit/veg till after other foods eaten. Smoothies or milkshakes often better tolerated. Bloating and nausea with refeeding common initially but should improve.

Family based treatment is recommended by NICE as first line. Emphasises that parents initially take back responsibility for feeding, then gradually handing it back to the young person.  Minimisation of blame.  If ineffective then CBT.

Psychotropic medication not recommended – metanalysis found no benefit from antidepressants in anorexia.

No evidence based guidelines for re-introduction of nutrition/energy in adolescents!

For the majority of patients, 40kcal/kg/day (1200kcal/day) appears to be safe – don’t start a meal plan with less calorific content than they were receiving prior to admission, although difficult when history of the amount taken is unclear.

  • The meal plan should comply with normal macronutrient guidelines (10-15% protein, 30-35% fat, 50-60% carbohydrates).
  • Increase the meal plan by 200kcal/day until 2000kcal/day is achieved.

Fluid 50ml/kg/d for 15yr+, 55ml/kg/d 11-14yr (Shaw et al).  GOSH use standard paediatric fluid requirement calculations.

Promote weight gain 0.5kg/week (NICE 2004, Junior Marsipan 2012).  Ignores malnutrition, of course.  Percentage weight for height used, but easiest to divide BMI by median BMI for age/sex – 85% is underweight, 90% is satisfactory.

Check electrolytes, calcium, phosphate, magnesium, liver function, vit D on admission.  QTc must be calculated MANUALLY (to find end of T, draw tangent through steepest part of curve).

All patients should be prescribed prophylactic dose of Vitamin D at a dose of 800IU/day whilst waiting for Vitamin D levels to be reported.

Prophylactic phosphate should not be routinely prescribed, however it should be considered where:

  • There has been a previous history of re-feeding syndrome.
  • Multiple risk factors

Consider Thiamine where starvation has been very prolonged (e.g. greater than one year at very low weight and poor intake) or there is a concern about vitamin deficiency.

A low phosphate (<1.1 mmol/L) before initiating feeds is unusual (see below) and should be corrected as soon as is possible on the day of admission:

  • Low phosphates should be discussed with the responsible consultant.
  • Give two sandoz-phosphate tablets and commence TDS regular phosphate regime.
  • Recheck U&E in 12 hours and monitor clinically (see below).
  • Do not make any increases on the feeding regime until phosphate has been corrected.
  • If phosphate is still low at 12 hours then consider repeated double dose, or IV correction. This is unusual.
  • Other causes of low phosphate should be excluded – in particular Vitamin D deficiency and hypoparathyroidism: check PTH and Vitamin D with next set of bloods (if hasn’t already been checked). These bloods should not hold up commencing of feeding once phosphate is normalised.
  • If phosphate is significantly low (<0.5) consider IV replacement – this will generally mean transfer to a medical ward.
  • Phosphates that are potentially dangerously low (<0.3) should be managed on a medical ward/PICU and discussions should occur with the consultant and CSPs about transfer before commencing feeding.

Refeeding syndrome

Biochemical abnormalities AND cardiovascular and neurological findings.  Onset is in first 48 hours, up to first five days of initiating feeding (cases up to 18 days later described -consider at risk for up to 20 days).  Cardiac arrest has occurred.

Early finding is drop in phosphate (increased requirement as body switches back to carbohydrate metabolism, plus chronic phosphate depletion due to starvation). Potassium, Mg also fall. 

All patients considered at risk of re-feeding syndrome should be monitored for clinical signs of the re-feeding syndrome:

  • Resting tachycardia (differential for this includes anxiety).
  • Oedema or swelling, especially in the legs.
  • Confusion or altered conscious state (always check glucose in this case).

Patients should have:

  • Daily inspection for any signs of oedema (in particular peripheral oedema) for first five days.
  • Three times/day resting pulse and lying and standing blood pressure for first five days.
  • Monitor for biochemical/blood parameters of the re-feeding syndrome:
  • Daily urea, creatinine, sodium, potassium, phosphate, magnesium daily for five days. The drop in phosphate seen when re-feeding will normally occur within 48-72 hours.

[http://www.gosh.nhs.uk/health-professionals/clinical-guidelines/refeeding-guidelines-children-and-young-people-feeding-and-eating-disorders-admitted-mildred-creak]

Current GOSH study, issue may be more the degree of malnutrition than the rate of re-feeding, so perhaps guidelines excessively cautious.

Admission criteria

  • %IBW <75%
  • Dehydration
  • Electrolyte disturbance (hypokalaemia, hypocalcaemia, hypomagnesaemia)
  • Cardiac dysrhythmia (can occur even in absence of electrolyte disturbance)
  • Syncope / Seizures
  • Cardiac failure
  • Pancreatitis
  • Severe bradycardia
  • Hypotension
  • Hypothermia
  • Acute food refusal
  • Failure of OP treatment
  • Uncontrollable binging and purging
  • Suicidal ideation
  • Acute psychosis
  • Co-morbid diagnosis that interferes with treatment eg OCD

Hypokalaemia can be due to vomiting, diuretic/laxative misuse. 

“Check bloods regularly” – ? Responsibility

Multivitamin and Thiamine 100mg bd for 10/7

[BMJ 2017; 359 Helen Bould]

Junior MARSIPAN: Management of Really Sick Patients under 18 with Anorexia Nervosa.  January 2012.

Patient information