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Free Thyroxine (Free T4)

Free Thyroxine (Free T4)

The main hormone made by the thyroid — confirms an under- or over-active thyroid with TSH.

Free T4 is the free, active part of the thyroxine hormone. Low Free T4 with high TSH confirms an underactive thyroid; high Free T4 with low TSH points to an overactive one.

It is also used to follow thyroid treatment doses every few months.

Preparation before the test

No fasting needed; it can be done any time.
Stop biotin (B7) supplements 48 hours before; it affects the result.

This information is for awareness only and is not a substitute for medical advice — your treating doctor interprets the result for your case.

Related tests

Thyroid & HormonesTSH

Thyroid Stimulating Hormone (TSH)

The first thyroid test: picks up an under- or over-active thyroid before symptoms are obvious.

Blood sample
No fasting
Within 6 hours
Available at home

220 EGP

Thyroid & HormonesFT3

Free Triiodothyronine (Free T3)

The most active thyroid hormone, important in diagnosing an overactive thyroid.

Blood sample
No fasting
Within 6 hours
Available at home

230 EGP

Thyroid & HormonesPRL

Prolactin

A high level can affect periods, ovulation and fertility in women and men.

Blood sample
No fasting
Within 24 hours
Available at home

260 EGP