Thyroid hormone (T3)
Liothyronine sodium (T3)
Brand names: Cytomel, Tertroxin
Adult dose
Dose: Hypothyroidism (rare indication): 10–20 micrograms/day initially, increase. Myxoedema coma: 5–20 micrograms IV every 12h with hydrocortisone
Route: PO/IV
Frequency: OD-BD
Clinical pearls
- Myxoedema coma (specialist); occasional adjunct with levothyroxine in selected hypothyroid patients (controversial)
- Short half-life — divided dosing; avoid evening doses (insomnia)
Contraindications
- Untreated thyrotoxicosis
- Untreated adrenal insufficiency
- Severe ischaemic heart disease (caution)
- Recent MI
Side effects
- Tachycardia
- Atrial fibrillation
- Heat intolerance
- Weight loss
- Bone loss
- Angina
Interactions
- Warfarin (raised INR)
- Insulin/sulfonylureas (altered glucose)
- Iron / calcium / antacids (separate)
Monitoring
- TFTs (free T3 alongside TSH)
- HR
- ECG
Reference: BNF; BTA position statement; https://bnf.nice.org.uk/drugs/liothyronine-sodium/. Verify against your local formulary and the latest BNF before prescribing.
Related
Curated clinical cross-links plus same-class fallbacks.
Calculators
- Corrected Sodium (Hyperglycaemia) · Electrolytes
- Thyroid Function Interpreter · Thyroid
- Burch-Wartofsky Point Scale for Thyrotoxicosis · Thyroid
- Weight-Based Levothyroxine Dose Calculator · Thyroid
- Burch-Wartofsky Score (Thyroid Storm) · Thyroid Crisis
- Thyroid Function Test Interpretation · Thyroid Disease
Pathways
- Diabetic Ketoacidosis (DKA) · JBDS 2013 / Joint British Diabetes Societies; NICE NG17
- Adult Hypoglycaemia (Treated Diabetes) · JBDS-IP (2023): Hospital Management of Hypoglycaemia
- Adrenal Crisis · Society for Endocrinology Emergency Guidance (2024)
- Type 2 Diabetes Management · NICE NG28 2022
- Hyperthyroidism Management · BTA / ETA 2018
- Adrenal Insufficiency · Society of Endocrinology / ESE 2016