A thyroid panel usually reports TSH plus Free T3 and Free T4. These values work together, so reading them as a group is more informative than looking at any one alone.
How the three tests relate
TSH (thyroid-stimulating hormone) is the signal from your pituitary telling the thyroid how hard to work. Free T4 and Free T3 are the thyroid hormones themselves.
When the thyroid is underactive, TSH typically rises as the body tries to push it harder; when overactive, TSH usually falls. That is why TSH and the thyroid hormones often move in opposite directions.
Reading the panel together
A typical TSH reference range is roughly 0.4–4.0 mIU/L, but labs differ, so compare against the range on your report. Free T4 and Free T3 ranges are reported alongside.
Because thyroid values shift gradually, tracking them across tests is especially useful for spotting a developing pattern.
Frequently asked questions
What is a normal TSH level?
A common reference range is about 0.4–4.0 mIU/L, but ranges vary by lab. Always compare against the range printed on your own report.
Why test T3 and T4 if TSH is normal?
TSH is a sensitive first signal, but Free T3 and Free T4 show the actual hormone levels. Reading all three together gives a fuller picture.
Can thyroid results change over time?
Yes. Thyroid function can drift gradually, so tracking TSH, Free T3, and Free T4 across several tests helps reveal a trend.