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The dose of levothyroxine (L-T4) depends on the severity of hypothyroidism, etiology, age, special conditions, weight, and individual differences. This calculator provides a basic reference for the L-T4 treatment dose for hypothyroid patients. More precise medication adjustments need to be combined with thyroid function reports and clinical manifestations.
Oral, preferably taken on an empty stomach in the morning (at least half an hour before breakfast) or before bedtime, once a day.
| Patient Type | Starting Dose | Full Replacement Dose |
|---|---|---|
| Adults | Starting 25~50 μg/d, increasing by 25 μg every 3~7 days until the treatment target is reached | 1.6~1.8ug·kg-1·d-1 |
| Elderly, with heart disease | Starting with a small dose of 12.5 μg/d, increasing by 12.5 μg every 1~2 weeks, slowly increasing the dose | 1.0ug·kg-1·d-1 |
| Children | Starting 12.5-50μg/d | 2.0ug·kg-1·d-1 |
| Pregnant women | Starting with the full replacement dose or increasing to the treatment dose as soon as possible | 20%-30% higher than pre-pregnancy |
Mainly symptoms of hyperthyroidism caused by drug overdose, such as palpitations, tachycardia, tremors, sweating, insomnia, weight loss, etc. If adverse reactions occur, the dose should be reduced or discontinued until the symptoms disappear, and then restarted at a lower dose. Serum FSH and FT4 should be measured after 4~6 weeks to determine if the treatment target is reached.
1. Chinese Medical Association, Guidelines for Rational Drug Use in Primary Hypothyroidism [J]. Chinese Journal of General Practitioners, 2021, 20(05):520-522.
2. National Medical Products Administration Center for Drug Evaluation. Technical Guidelines for Bioequivalence Studies of Narrow Therapeutic Index Drugs. 2020 No. 62.
3. Compilation of Literature on Narrow Therapeutic Index Drugs. Shanghai Medicine. 2020;41(Supplement 2):22-24.
4. Lillevang-Johansen M, et al. Thyroid. 2018 May;28(5):566-574.
5. Flynn RW, et al. J Clin Endocrinol Metab 2010,95(1):186-93.
6. Dan Zhongyan, Teng Weiping. Thyroid Hormones - 70 Years of Clinical Application [J]. Chinese Journal of Endocrinology and Metabolism, 2020(05):365-370.
7. Benvenga S, Carlé A. Adv Ther. 2019 Sep;36(Suppl 2):59-71.