On the Fundamental Efficacy of Thyroid-Hormone Therapy in Eating Disorders: Review of Mechanisms and Case Study

Context: Calorie restriction reduces circulating triiodothyronine (T3) – the most active thyroid hormone – inducing hypothyroidism, constipation, and reduced appetite that inhibit eating, acting to sustain and sometimes precipitate eating disorders. Thyroid-hormone treatment can be effective but is rarely employed. Case description: A 12-year-old girl experienced chronic nausea and constipation after antibiotics for strep throat, resulting in restricted eating. Energy decreased for 2 months as anxiety and depression increased, culminating in withdrawal and school refusal. Blood tests were normal except for below-range free T3. She began a trial of incremental, 1-μg dose increases of T3 every 3 days using sustained-release capsules added to her established triiodothyronine–levothyroxine (T3–T4) protocol for hypothyroidism. Her energy and mood began improving after 10 days and depression resolved after 7 weeks. An 18-day stay in a hospital eating-disorders unit helped her regain some weight and strength. To address nausea and anxiety, the extended medical team then tried two antidepressants and cyproheptadine – each caused increased nausea and reduced eating – and a 5-day prednisone burst for possible neuroinflammation; all were ineffective and discontinued. After 14 weeks without improvement, we resumed adjusting thyroid-hormone dose. Anxiety, energy, food intake, and weight improved for 5 months. She began attending a new school, developed new friendships, and started menses. The major illness lasted 21 months. T3 intake increased from 5 to 27 μg, T4 from 50 to 110 μg, weight from 36.4 to 52.7 kg, and height from 1.63 to 1.71 m. Conclusions: Thyroid hormones should be studied further as fundamentally effective treatment for eating disorders.