Medically unstable anorexia nervosa in a 15-year-old
A 15-year-old girl is brought to the emergency department by her parents after fainting at school. Over 7 months she has lost 11 kg, now weighs 38 kg at 165 cm (BMI 14.0), and has been eating only 'safe' foods, exercising secretly, and vomiting after meals. She has lanugo hair, cold peripheries, and a pulse of 46/min. Blood pressure is 88/56, temperature 35.8°C, and capillary refill is delayed. Potassium is 2.9 mmol/L, sodium 132, phosphate 0.9 mmol/L, and creatinine is mildly raised. Her parents refuse admission because they believe 'she will eat at home' and fear stigma from relatives. The girl says she feels fat and does not want to be admitted, but she can explain the risks and says she wants to 'feel better.' The team has a bed in a medical ward with psychiatric liaison input.
1. Does she need medical admission, and what findings drive that decision?
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Yes. She meets criteria for medically unstable anorexia nervosa and needs admission to a medical or specialist eating-disorder bed with psychiatric liaison, not outpatient management. The decision is not based on weight alone; it is based on physiological compromise.
Key drivers:
- Bradycardia of 46/min, hypotension and delayed capillary refill indicate poor perfusion.
- Hypothermia at 35.8°C.
- Hypokalaemia of 2.9 mmol/L with purging is a risk for arrhythmia.
- Dehydration and mildly raised creatinine.
- Low phosphate at 0.9 mmol/L, which raises concern for refeeding syndrome once nutrition is started.
- Rapid weight loss of 11 kg over 7 months and BMI 14.0.
- Fainting suggests syncope, possibly from orthostasis or arrhythmia.
She also has purging, secret exercise and body-image distortion, which increase the risk of deterioration. She does not need to be at a very low BMI to be medically unstable; the combination of bradycardia, hypotension, hypokalaemia and syncope is enough. The parents' preference and stigma concerns are important but do not override immediate medical risk. Explain that admission is for physical stabilisation, not punishment, and that the team will work with the family. If the parents continue to refuse, child protection and the legal framework for treatment of a minor should be used promptly.
2. How do you assess her capacity and handle consent and the family's refusal?
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Capacity in a 15-year-old is assessed functionally, not by age alone. Ask whether she can understand the risks of continued starvation and purging, retain the information, weigh it, and communicate a choice. She can explain some risks and says she wants to feel better, but anorexia nervosa can distort the weighing process, especially around food and weight. A structured conversation, repeated when she is medically stable, is better than a single judgement. Document examples of her reasoning.
Even if she has capacity, this does not settle the matter. A minor's consent and refusal exist within a legal framework that also involves parental responsibility and, where refusal risks death or serious harm, child protection. The team should:
- Explain the medical findings to the parents in plain language and separate stigma from risk.
- Offer family-based support and involve a trusted relative or community figure if that helps.
- Be clear that treatment can begin while consent discussions continue, if the law permits emergency treatment for life-threatening risk.
- Escalate to the designated child protection lead and, if necessary, the courts or statutory authority.
- Avoid framing the parents as adversaries; aim for a shared plan with clear boundaries.
The judgement is that her refusal and the parents' refusal do not justify discharge when she is medically unstable. If she has capacity, her views should be heard, but the legal and ethical duty to prevent serious harm may still permit treatment over objection under the applicable framework.
3. Outline the first 72 hours of nutritional and psychiatric management, including refeeding risk.
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The first 72 hours should prioritise safety, electrolytes and a cautious start to nutrition.
Medical:
- Continuous cardiac monitoring if bradycardic or hypokalaemic; correct potassium and magnesium cautiously and recheck frequently.
- Check phosphate, calcium, magnesium, renal function, glucose and ECG (QTc).
- Start oral or enteral nutrition at a low rate because she is at high risk of refeeding syndrome: approximately 5–10 kcal/kg/day in the first 24 hours, with slower advancement in severe risk. Do not aim for rapid weight gain.
- Give thiamine before or with feeding, and monitor for refeeding syndrome: falling phosphate, potassium, magnesium, fluid overload, confusion, weakness and arrhythmia.
- Restrict strenuous activity; monitor pulse, blood pressure and temperature. Treat hypoglycaemia and hypothermia.
Psychiatric:
- Engage her with a supportive, non-judgemental stance; explain that the team is treating the physical consequences first.
- Start psychoeducation about anorexia nervosa and the function of the symptoms, but do not force a full psychotherapy contract in the first 72 hours.
- Involve the family in a structured way, preferably with a family-based approach after medical stabilisation.
- Assess for depression, anxiety, OCD, trauma and suicide risk; do not start antidepressants routinely for weight-related symptoms alone.
- Avoid coercive feeding unless life-saving and legally authorised. Use clear boundaries, meal supervision and a behavioural plan.
The reasoning is that refeeding too fast can kill her, while continued starvation can also kill her. The safest course is a monitored medical admission with slow refeeding and early psychiatric engagement.