Use

Measuring free T3 (triiodothyronine) is essential for effective hormone management and health optimization, as it provides a more accurate picture of active thyroid function than TSH or total T3 alone. Free T3 is the most biologically active thyroid hormone, directly influencing metabolism, energy production, temperature regulation, and overall well-being. Since T3 is converted from T4, testing free T3 can help identify conversion issues that may not be apparent in a standard thyroid panel. This is particularly important for individuals experiencing symptoms of hypothyroidism, such as fatigue, brain fog, weight gain, depression, and poor temperature regulation, despite having normal TSH or T4 levels.

For hormone management, free T3 testing is crucial in optimizing thyroid therapy, especially for patients on T4-only medications (like levothyroxine), as some may struggle to convert T4 into the active T3 form efficiently. This test helps guide personalized treatment, whether through adjusting T4 doses, adding liothyronine (T3), desiccated thyroid extract, or addressing nutrient deficiencies (such as selenium and zinc) that affect T4-to-T3 conversion. In functional medicine and anti-aging approaches, optimizing free T3 levels is also linked to better cognitive function, improved metabolism, and overall vitality, making it a key marker for those aiming to enhance long-term health and quality of life.

Preparation 

Patients should be cautioned to stop biotin consumption at least 72 hours prior to the collection of a sample.