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Thyroid
Free T3
Measures the active form of thyroid hormone in the blood.
What it measures
It measures the amount of free triiodothyronine in the blood.
Why it is tested
It is commonly used to assess thyroid hormone activity in more detail.
Low results
Low results may be associated with an underactive thyroid or illness.
High results
High results may be associated with an overactive thyroid.
Related tests
TSH, Free T4, Thyroid peroxidase antibodies
Sources
Other markers
Disclaimer
This information is for education only and is not a substitute for medical advice. Results should be interpreted by a qualified clinician alongside your symptoms and medical history.