When you’re scheduled for a
thyroid function test (like
TSH, T3, or T4), it is generally advised not to take your thyroid medication before the blood test. This is because the medication can temporarily raise your thyroid hormone levels and may not provide an accurate reflection of your thyroid function.
It’s usually recommended to take your thyroid medication after the blood draw. If your doctor has specific instructions that differ from this general advice, it’s best to follow their guidance.
For the most accurate results, it’s also often recommended to do the blood test first thing in the morning, before you take any medication.