From the Research
The equivalent Armour Thyroid dose for someone previously taking 75 mcg of levothyroxine would be approximately 45-60 mg (typically starting with 45 mg or 3/4 grain). When switching from levothyroxine to Armour Thyroid, it's essential to understand that Armour contains both T4 (levothyroxine) and T3 (liothyronine) hormones, while levothyroxine contains only T4. The conversion is not exact, but generally, 100 mcg of levothyroxine is roughly equivalent to 60 mg (1 grain) of Armour Thyroid, as supported by a study published in 2021 1.
Key Considerations
- The transition should be monitored with thyroid function tests after 6-8 weeks to ensure proper dosing.
- Patients may experience different symptoms during the transition as the body adjusts to receiving both T3 and T4 directly rather than converting T4 to T3 naturally.
- Take Armour Thyroid in the morning on an empty stomach, at least 30-60 minutes before eating, and separate it from calcium, iron supplements, and certain medications that can interfere with absorption.
- Some patients may require dose adjustments based on symptoms and lab results, as indicated by a systematic review and meta-analysis published in 2024 2.
Evidence-Based Recommendations
The most recent and highest quality study, published in 2024 2, suggests that combined therapy with T4 and T3, or desiccated thyroid, may lead to higher T3 and lower T4 levels compared to T4 monotherapy in hypothyroidism. However, no significant effects on heart rate, lipid profile, or quality of life were noted. Given the heterogeneity of results, personalized treatment approaches are recommended.
Clinical Implications
In clinical practice, the decision to switch from levothyroxine to Armour Thyroid should be based on individual patient needs and responses to treatment, as supported by a study published in 2021 1. Patients who remain symptomatic on levothyroxine therapy may benefit from a trial of combination therapy with LT4+LT3, as recommended by clinical guidelines 3.