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T4


Formal name: thyroxine
Related tests: TSH; T3; FT4; FT3

At a Glance

Why Get Tested?

To diagnose hypothyroidism or hyperthyroidism in adults

When to Get Tested?

It has largely been replaced by measurement of FT4 but may still be is measured in response to an abnormal TSH test result

Sample Required?

A blood sample taken from a vein in the arm