Free T3 Test

Why is Free T3 tested instead of Total T3?

Free T3 measures only the biologically active hormone that isn't bound to carrier proteins, giving a more reliable picture that isn't distorted by changes in protein levels (which can happen during pregnancy or with certain medications).

Can Free T3 be abnormal while TSH is normal?

This is uncommon but can occur in certain situations, which is why doctors typically evaluate TSH, Free T3, and Free T4 together rather than relying on any single value.