Does taking Armour Thyroid (desiccated thyroid) in the morning affect thyroid blood test results?

Taking Armour Thyroid Before Thyroid Blood Tests

Yes, taking Armour Thyroid (desiccated thyroid) in the morning before a thyroid blood test will significantly affect the results and should be avoided.

Impact on Thyroid Blood Test Results

• Taking Armour Thyroid before a blood draw can cause falsely elevated T3 levels, as serum T3 frequently rises to supranormal values in the absorption phase after taking desiccated thyroid preparations 1
• Desiccated thyroid contains both T4 and T3, and the T3 component has a short half-life with peak serum levels occurring approximately 2 hours after ingestion 2
• The FDA label for thyroid medications indicates that periodic assessment of thyroid status requires appropriate laboratory tests, which can be affected by the timing of medication administration 3

Proper Testing Protocol

• For accurate thyroid function assessment, blood samples should ideally be drawn before the patient takes their morning dose of Armour Thyroid 3
• Morning hormone levels (around 8 am) are preferred for thyroid function testing, particularly when evaluating TSH, free T4, and other thyroid parameters 4
• Laboratory confirmation of thyroid status is most accurate when medication effects are at their lowest point (trough levels), which occurs before the next scheduled dose 4

Clinical Implications

• Inaccurate test results due to improper timing can lead to:
  • Inappropriate medication adjustments
  • Overtreatment or undertreatment of hypothyroidism
  • Difficulty achieving optimal thyroid hormone balance 1

Special Considerations with Armour Thyroid

• Unlike synthetic levothyroxine (T4 only), Armour Thyroid contains both T4 and T3, making the timing of blood tests even more critical 1
• The T3 component in Armour Thyroid has a much shorter half-life than T4 and causes more pronounced fluctuations in serum levels 2
• A bioavailability study showed that peak Free T3 Index occurs approximately 2 hours after taking T3-containing preparations, compared to 2 days for T4-only preparations 2

Recommendations for Accurate Testing

• Schedule blood draws before taking the morning dose of Armour Thyroid 3
• If the blood test has already been scheduled for later in the day, consider:
  • Postponing the morning dose until after the blood draw
  • Rescheduling the blood test for early morning before taking medication
• Maintain consistency in the timing of blood tests relative to medication administration for reliable trend monitoring 4

Potential Pitfalls

• Inconsistent timing of blood tests relative to medication can lead to misinterpretation of thyroid function 3
• Failure to account for medication timing may result in unnecessary dose adjustments 1
• Some patients taking desiccated thyroid preparations may have thyroid test results that don't correlate well with clinical symptoms, making proper testing protocol even more important 5

Remember that accurate assessment of thyroid function is essential for proper management of hypothyroidism and optimal patient outcomes.