Discussions that mention synthroid

Thyroid Disorders board


Fasting is not needed for any thyroid test. If you're having something else tested with the same blood draw, like cholesterol or blood glucose, then you must.

If you take a levothyroxine-only med, and if you are having your free T4 measured, it's better to take the med after the blood draw in order to get an accurate measure.

To repeat what I've said before ~

If you are taking Synthroid or any other brand of levothyroxine within 8 hours before a blood test, it will falsely elevate the result of your FreeT4 test, but not Total T4, Free T3, Total T3, T3 Uptake or TSH.

If you are taking Armour thyroid (or any combination of T3 and T4) within 8 hours before a blood test, it will falsely elevate the result of your Free T3 and Free T4, but shouldn't have an effect on Total T3, Total T4, T3 Uptake, or TSH.

If you are taking Cytomel within 8 hours before a blood test, it will falsely elevate the result of your FreeT3 test, but not Total T3, Free T4, Total T4, T3 Uptake or TSH.