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Formal name: Free Thyroxine
Related tests: TSH; Free T3; Total T3; Total T4

At a Glance

Why Get Tested?

To diagnose hypothyroidism or hyperthyroidism in adults and to monitor response to treatment

When to Get Tested?

When you have symptoms of an underactive (hypothyroidism) or overactive (hyperthyroidism) thyroid gland

Sample Required?

A blood sample taken from a vein in the arm

Test Preparation Needed?

No test preparation is necessary