What is the recommended initiation and titration protocol for Armour Thyroid (desiccated thyroid) in a patient with elevated Thyroid-Stimulating Hormone (TSH) levels?

Initiating Armour Thyroid for TSH 12

Do Not Use Armour Thyroid as First-Line Therapy

Levothyroxine (T4) monotherapy, not Armour Thyroid (desiccated thyroid extract), is the recommended first-line treatment for hypothyroidism with TSH 12 mIU/L. 1, 2

The evidence strongly supports levothyroxine as the standard of care because it provides uniform levels of both T4 and T3 without diurnal variation, whereas desiccated thyroid extract (DTE) like Armour Thyroid has an unphysiologic T4:T3 ratio of approximately 4:1 and remains outside formal FDA oversight for consistency of hormone content. 3, 4

When Desiccated Thyroid Extract Might Be Considered

Armour Thyroid should only be considered as a trial therapy for patients who remain symptomatic despite adequate levothyroxine treatment with normalized TSH levels. 4

• DTE is not recommended for newly diagnosed hypothyroidism 4
• Clinical guidelines recommend trying combination T4+T3 therapy (or DTE) only after documented failure of levothyroxine monotherapy 4
• The mean daily dose of DTE needed to normalize TSH contains approximately 11 mcg T3, though some patients may require higher doses 4

Critical Safety Considerations Before Any Thyroid Hormone Initiation

Before starting any thyroid hormone replacement, you must rule out concurrent adrenal insufficiency, as initiating thyroid hormone before corticosteroids can precipitate life-threatening adrenal crisis. 5, 1

• If central hypothyroidism or hypophysitis is suspected, always start physiologic dose steroids 1 week prior to thyroid hormone replacement 5, 1
• This applies to both levothyroxine and desiccated thyroid preparations 1

Recommended Approach: Start with Levothyroxine

Initial Dosing Strategy

For patients <70 years without cardiac disease, start levothyroxine at the full replacement dose of 1.6 mcg/kg/day. 1, 6

For patients >70 years or with cardiac disease/multiple comorbidities, start with a lower dose of 25-50 mcg/day and titrate gradually. 5, 1

• Elderly patients and those with coronary artery disease are at increased risk of cardiac decompensation, angina, or arrhythmias even with therapeutic doses 3, 2
• Starting low and titrating gradually is essential in these populations 3, 7

Monitoring and Titration

Recheck TSH and free T4 every 6-8 weeks after any dose adjustment until TSH normalizes within the reference range (0.5-4.5 mIU/L). 5, 1, 6

• If TSH remains above the reference range, increase levothyroxine by 12.5-25 mcg based on current dose and patient characteristics 5, 1
• Use smaller increments (12.5 mcg) for elderly patients or those with cardiac disease 1
• Free T4 can help interpret ongoing abnormal TSH levels during therapy, as TSH may take longer to normalize 1, 6

Once adequately treated with stable TSH, monitor annually or sooner if symptoms change. 5, 1, 6

If Considering Armour Thyroid After Levothyroxine Failure

Prerequisites for Trial

• Patient must have been on adequate levothyroxine dose with normalized TSH for at least 3-4 months 1, 8
• Patient must have persistent symptoms despite biochemical euthyroidism 4, 8
• Clear documentation of symptoms and plan to reassess benefit after 3-4 months 8

Conversion Approach

When switching from levothyroxine to DTE, reduce the levothyroxine dose by approximately 25 mcg and start DTE at a dose that provides roughly equivalent T4 content, recognizing that DTE contains additional T3. 4

• The T4:T3 ratio in DTE is approximately 4:1, which is more T3 than physiologic 4
• Monitor for transient hypertriiodothyroninemia, though doses used typically do not exceed reference range 4

Monitoring on DTE

Recheck TSH and free T4 (and consider free T3) 6-8 weeks after starting or adjusting DTE. 1, 4

• Target TSH in the lower half of reference range (0.4-2.5 mIU/L) 8
• Be aware that consistency of T4 and T3 content in DTE is monitored only by manufacturers, not FDA 4

Common Pitfalls to Avoid

Do not start with Armour Thyroid for newly diagnosed hypothyroidism—this deviates from evidence-based guidelines and standard of care. 3, 2, 4

Avoid overtreatment, which occurs in 14-21% of treated patients and increases risk for atrial fibrillation, osteoporosis, fractures, and cardiac complications. 1, 3

• Approximately 25% of patients are inadvertently maintained on doses sufficient to fully suppress TSH 1
• Prolonged TSH suppression significantly increases cardiovascular and bone risks, especially in elderly patients 1, 3

Never adjust doses more frequently than every 6-8 weeks before reaching steady state. 5, 1

If patient shows no symptom improvement after 3-4 months on DTE with normalized TSH, discontinue and return to levothyroxine monotherapy. 8

Special Population Considerations

Pregnancy

Women with hypothyroidism who become pregnant should increase their levothyroxine dose by 30% immediately (take one extra dose twice per week), followed by monthly monitoring. 2

• This applies to levothyroxine therapy; DTE is not recommended during pregnancy 2

Cardiac Disease

For patients with atrial fibrillation, cardiac disease, or serious medical conditions, consider more frequent monitoring within 2 weeks of dose adjustment rather than waiting 6-8 weeks. 1, 6

Immunotherapy Patients

For patients on immune checkpoint inhibitors with thyroid dysfunction, continue immunotherapy in most cases while treating hypothyroidism, as thyroid dysfunction rarely requires treatment interruption. 1