Thyroxine-Free

What Does This Test Check?

Free T4 is the thyroid hormone available to your body's tissues, and it is the standard partner test to TSH when thyroid function is being assessed.

Lola Health lists this as an add-on biomarker at £12, posted as a home sample with results in one to four working days. It cannot be bought on its own: you pick it while ordering one of Lola's main blood tests, so it suits someone who already knows which extra marker they want.

An abnormal level may indicate an under- or overactive thyroid, and the TSH-to-T4 pattern together tells which direction. One reading can wobble with illness and timing. Whatever the reading, an out-of-range result needs a doctor who can see the whole picture, so go through it with your GP before acting on it.