Adjusting Armour Thyroid When TSH is Elevated
When TSH is elevated on Armour Thyroid, increase the dose by 15 mg every 2-3 weeks until TSH normalizes, then recheck TSH 4-8 weeks after each adjustment. 1
Dose Adjustment Protocol
The FDA-approved dosing strategy for Armour Thyroid is straightforward and algorithmic 1:
- Standard increment: Increase by 15 mg every 2-3 weeks
- Timing of lab reassessment: Check TSH 4-8 weeks after each dose change 2
- Target maintenance range: Most patients require 60-120 mg daily 1
- Maximum threshold: Failure to respond to 180 mg suggests non-compliance or malabsorption 1
Special Populations Requiring Caution
Elderly or Cardiac Disease
For patients over 50-60 years or those with known coronary heart disease, use smaller increments of 12.5 mg and monitor closely for anginal symptoms 2. The appearance of angina mandates immediate dose reduction 1.
Long-standing Hypothyroidism
Patients with severe, long-standing myxedema require extreme caution with slower titration, particularly if cardiovascular impairment is suspected 1.
Monitoring Strategy
Recheck TSH and free T4 levels 4-8 weeks after each dose adjustment 2. This timing is critical because:
- Smaller dose changes may require 8 weeks or longer before TSH plateaus 2
- Adequate therapy typically normalizes TSH and T4 within 2-3 weeks of reaching the optimal dose 1
Once stable, monitor TSH at 6-month intervals, then annually 2.
Common Pitfalls to Avoid
Non-compliance vs. True Resistance
Before escalating doses beyond 180-200 mg daily, always investigate compliance and absorption issues first 2. Persistently elevated TSH on high doses most commonly reflects:
- Non-compliance (most common) 2
- Malabsorption from food or drug interactions 2
- Medications interfering with absorption (see below)
Absorption Interference
Armour Thyroid should be taken 30-60 minutes before breakfast or 4 hours after the last meal 2. Key interfering substances include 2:
- Calcium supplements
- Iron supplements
- Proton pump inhibitors
- Soy products
- High-fiber foods
Variable T4:T3 Ratio
Important caveat: Desiccated thyroid preparations like Armour Thyroid contain a fixed T4:T3 ratio of approximately 4:1 by weight, which differs from physiologic production 2. The T3 content may cause transient supraphysiologic T3 levels even when TSH is elevated, complicating interpretation.
When to Suspect Problems
If TSH remains elevated despite doses >180 mg daily 1:
- Verify compliance through direct questioning and pill counts
- Review timing of medication relative to meals
- Check for interfering medications added since last stable dose 2
- Consider malabsorption (celiac disease, atrophic gastritis, inflammatory bowel disease)
- Evaluate for adrenal insufficiency if TSH elevation persists with normal free T4 2
Guideline Perspective on Desiccated Thyroid
Critical note: The 2012 AACE/ATA guidelines explicitly state there is no evidence supporting desiccated thyroid hormone over levothyroxine monotherapy and recommend against its use (Grade D recommendation) 2. However, for patients already established on Armour Thyroid with elevated TSH, the dose adjustment principles above remain valid based on FDA labeling 1.