Adolescent anorexia nervosa — medical risk, FBT and refeeding (MEQ)

(i) Definition and differentials. AN (DSM-5): energy restriction leading to significantly low weight/growth failure; intense fear of weight gain or persistent behaviour interfering with weight gain; body weight/shape disturbance or undue influence on self-evaluation or persistent lack of recognition of seriousness. Amenorrhoea not required. Here: marked loss, restriction, driven exercise, medical sequelae. Differentials: organic (coeliac, IBD, hyperthyroid, diabetes, malignancy), depression, OCD contamination, psychosis, ARFID (no weight phobia), substance misuse. Discriminators: weight/shape overvaluation, fear of fatness, ritualised restriction vs systemic red flags.[5][2]

(ii) Medical risk and admission. Assess HR, orthostatic BP, temperature, hydration, ECG (bradycardia/QTc), electrolytes (K, phosphate, Mg), glucose, rate of loss, ability to eat safely at home, suicide risk. This case shows bradycardia, orthostasis, hypothermia, hypokalaemia, syncope — high medical risk. SAHM-style and Junior MARSIPAN-informed pathways support paediatric medical admission for monitoring and refeeding rather than outpatient hope alone. Do not discharge because she says she is “fine.”[2]

(iii) Refeeding. Protocolised nutrition (local paediatric dietetic pathway); thiamine; frequent phosphate/K/Mg; vitals and ECG as indicated; watch for oedema and arrhythmia. Refeeding syndrome = insulin-driven intracellular electrolyte shifts after carbohydrate reintroduction. StRONG: higher-calorie refeeding achieved faster weight gain without increased refeeding adverse events under monitoring versus lower starts — still requires protocol, not improvisation.[3][6]

(iv) FBT for parents. Externalise AN (illness, not bad parenting). Phase 1: parents take charge of meals/refeeding; unite against illness; stop negotiation with AN rules. Phase 2: gradual return of control as weight restores. Phase 3: adolescent development and relapse prevention. Evidence: Lock RCT FBT superior to AFT at follow-up for remission. Address parental guilt directly — FBT is empowerment, not blame.[1][5]

(v) SSRIs and capacity/legal. Fluoxetine is not indicated as AN weight-restoration or post-weight-restoration relapse prevention drug (Walsh RCT negative). Treat comorbid depression/anxiety later with caution once medical risk addressed. Capacity is decision-specific; starvation and overvalued ideas may impair weighing of medical risk. For minors, parental responsibility and best interests usually guide; if life-saving treatment refused and incapacitous, use local compulsory frameworks (Mental Health Act / child protection / court) — name jurisdiction, do not invent foreign section numbers. Prefer voluntary collaborative care when safe.[4][5]