Weight-Based Levothyroxine Dose Calculator
Estimates starting levothyroxine dose for hypothyroidism based on lean body weight and severity. Target dose for primary hypothyroidism: 1.6 mcg/kg/day. Lower in elderly (0.8–1.0 mcg/kg) and cardiac disease (12.5–25 mcg start).
Score interpretation
Weight-based levothyroxine dose calculated
→ Full replacement dose = weight × dose factor above. Start at 25–50 mcg in elderly/cardiac; 50–75 mcg in standard adults. Titrate every 6–8 weeks based on TSH. Target TSH: 0.5–2.5 mIU/L for most adults; TSH <0.1 for post-thyroid cancer suppression. Monitor FT4 in central hypothyroidism. Recheck TSH 6–8 weeks after dose change. Avoid taking within 4 hours of calcium, iron, antacids.
Interpretation bands for the Levothyroxine Dose. Apply clinical judgement and local guidance.
References
- Jonklaas J et al. Guidelines for the Treatment of Hypothyroidism: Prepared by the American Thyroid Association Task Force. Thyroid. 2014;24(12):1670–1751.
Related
Curated clinical cross-links plus same-class fallbacks.
- Levothyroxine · Thyroid Hormone
- Levothyroxine sodium · Thyroid hormone (T4)
- Levothyroxine (Elderly) · Thyroid Hormone
- Enoxaparin (VTE in Pregnancy) · Low Molecular Weight Heparin (LMWH) — VTE Prophylaxis/Treatment
- Low Molecular Weight Heparin (Pregnancy VTE) · Anticoagulant — VTE Treatment and Prophylaxis in Pregnancy
- Dalteparin · Low Molecular Weight Heparin — VTE Treatment / Cancer-Associated Thrombosis
- 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
Decision support only — verify against a current formulary, NICE, or your local guideline before clinical use.