Thyroid

Free T3

The unbound form of triiodothyronine available to tissues.

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About this biomarker

Free T3 measures the active thyroid hormone fraction not bound to proteins. It is commonly interpreted with TSH and free T4.

Why it matters

It can add detail in certain thyroid patterns, especially when overactivity is being evaluated.

What lower levels may suggest

Low free T3 may be seen in underactive thyroid patterns, illness, or reduced conversion from T4.

What higher levels may suggest

High free T3 may suggest an overactive thyroid pattern.

Common tests

Free T3, thyroid panel

Related biomarkers

Tsh Free T4 Glucose Total Cholesterol Ldl Cholesterol

Your trend

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Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health.