The FT4 test measures the level of free thyroxine, the active thyroid hormone that helps regulate metabolism, energy, and overall body function. Unlike total T4, this test focuses on the hormone not bound to proteins in the blood.
It’s commonly used to diagnose hypothyroidism or hyperthyroidism, and to monitor thyroid treatment.
• No fasting required.
• Do not take Biotin (Vitamin B7) for 8 hours prior to extraction.
• For patients taking medicines to lower cholesterol (D-T4), medication should be discontinued for 4-6 weeks prior to collection (please consult your doctor before following this preparation)