II. Indications
- Not generally recommended (no proven benefit and associated risk)
- Levothyroxine alone is preferred instead
- Levothyroxine (T4) is converted in peripheral tissues to Liothyronine (T3)
- May be used as an adjunct to Levothyroxine in Hypothyroidism
- Consider in lethargy or memory deficits despite normal TSH
III. Mechanism
IV. Medications
- Liothyronine (Cytomel): 5 mcg, 25 mcg and 50 mcg
-
Levothyroxine AND Liothyronine (Liotrix) combined tabs (T4/T3): 12.5/3.1 mcg, 25/6.25 mcg, 50/12.5 mcg, 100/25 mcg, 150/37.5 mcg
- Rare indications, but if used typically started in adults at 12.5/3.1 or 25/6.25 and titrated every 2 weeks
V. Dosing: Adults
- Combined with Levothyroxine
- Start: 1:14 ratio of Liothyronine to Levothyroxine
- Example: 5 mcg Liothyronine to 75 mcg Levothyroxine
- Typical Dose Range: 12.5 to 25 mcg orally daily
- Elderly: Start at 5 mcg/day (and titrate at 5 mcg/kg increments every 1 to 2 weeks)
- Maximum: 100 ug orally daily
VI. Adverse Effects
- Risk of Cardiovascular Risks when combined with Levothyroxine
- See Levothyroxine
VII. Safety
- Pregnancy Category A
- Unknown safety in Lactation
VIII. Efficacy
- May improve neuropsychiatric symptoms
- Changes after replacing T3 and T4
- Improved mood and energy
- Decreased confusion, fear, and irritability
- No difference in TSH normalization
- Studies suggests no benefit
IX. Resources
X. References
- (2017) Presc Lett 25(1): 4
- Bunevicius (1999) N Engl J Med 340:424 [PubMed]
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Related Studies
| liothyronine (on 12/21/2022 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| LIOTHYRONINE SOD 25 MCG TAB | Generic | $0.37 each |
| LIOTHYRONINE SOD 5 MCG TAB | Generic | $0.29 each |
| LIOTHYRONINE SOD 50 MCG TAB | Generic | $0.53 each |
| cytomel (on 1/1/2023 at Medicaid.Gov Survey of pharmacy drug pricing) | ||
| CYTOMEL 5 MCG TABLET | Generic | $0.29 each |