Dose Conversion from NP Thyroid to Armour Thyroid
When switching from NP Thyroid to Armour Thyroid, a 1:1 dose conversion is recommended as both are natural desiccated thyroid products with similar T4:T3 ratios of approximately 4.22:1.
Understanding Natural Desiccated Thyroid Products
- Both NP Thyroid and Armour Thyroid are natural porcine-derived thyroid supplements containing both T4 (thyroxine) and T3 (triiodothyronine) 1
- These products have a T4:T3 ratio of approximately 4.22:1, which differs from the body's natural secretion ratio of approximately 11:1 1
- The standardization of these products is based on their USP (United States Pharmacopeia) thyroid units, which allows for direct milligram-to-milligram conversion 2
Conversion Protocol
- Convert NP Thyroid to Armour Thyroid using a 1:1 ratio (e.g., 60 mg of NP Thyroid equals 60 mg of Armour Thyroid) 1, 2
- After switching, monitor thyroid function tests (TSH and free T4) after 6-8 weeks to assess response and make any necessary dose adjustments 3
- If TSH remains above the reference range after switching, consider increasing the dose by 12.5 to 25 mcg equivalent 4
Monitoring Recommendations
- Check thyroid function tests (TSH, free T4, and possibly free T3) 6-8 weeks after switching medications 3
- Once the appropriate maintenance dose is established, continue monitoring thyroid function annually or sooner if clinical status changes 3
- Monitor for symptoms of both hypothyroidism (fatigue, weight gain, cold intolerance) and hyperthyroidism (palpitations, heat intolerance, anxiety) 5
Special Considerations and Precautions
- For elderly patients (>70 years) or those with cardiac disease, use smaller incremental adjustments if needed after the initial conversion 3
- Be aware that natural desiccated thyroid products may cause T3 levels to rise transiently after administration due to their T3 content, potentially causing palpitations in sensitive individuals 6
- Patients with known coronary artery disease should be monitored more closely when using desiccated thyroid products due to potential cardiovascular effects of T3 7
- Avoid self-administration or adjustment of thyroid medication without physician supervision, as this can lead to serious adverse effects 7
Common Pitfalls to Avoid
- Do not assume bioequivalence between different manufacturers' products, even at the same labeled dose; monitor closely after switching 6
- Avoid allowing TSH to fall below 0.2 mIU/L as this may increase risk of atrial fibrillation and bone loss 6
- Do not make dose adjustments more frequently than every 6 weeks, as this is the time needed to reach a new equilibrium 6
- Be cautious about claims that desiccated thyroid products are superior for all patients; evidence is limited and individualized assessment is necessary 2