Thyroid Function (TSH, Free T3, and Free T4) Blood Test

Measures thyroid stimulating hormone, free T3 and free T4.

Measures

Thyroid stimulating hormone, free T3 and free T4.

Why it matters

TSH is the pituitary's signal to the thyroid; free T4 is the main hormone the thyroid releases; free T3 is the more active form that T4 converts into.

Reading the three together is what makes thyroid assessment work — TSH alone describes the signal without the response, and the relationship between signal and hormones is the informative part.

Before you collect

TSH varies across the day and is typically highest in the early morning. Morning collection, consistently, if you're comparing over time. If you take thyroid medication, discuss collection timing relative to your dose with your practitioner. Biotin supplements can interfere with thyroid assays — stop for 48 hours beforehand unless advised otherwise.

Suits

People assessing thyroid function with a practitioner.

Your next step

Once you have your results, book with a Canwell naturopath, nutritionist or practitioner to talk them through and build a wellness plan that suits you. Book with Canwell