Thyroid function tests
Also written: TFT / TSH
What it measures
TSH and thyroid hormones — measures of how the thyroid is working.
Why it is ordered
Often considered with prolonged fatigue, weight change, or unexplained changes in heart rate or mood.
How to prepare
Say if you take thyroid medicine and at what time — timing affects the result.
Units
mIU/L (TSH) — convert here
What to ask
- Should I take my thyroid medicine before or after the blood draw
- When should this be repeated
- Are any additional markers needed
This page does not include reference ranges and does not say whether your number is high or low. Reference ranges differ between laboratories and between people — read yours on your own report, with your clinician.