Thyroxine (T4), Free, Dialysis/Mass Spectrometry (Endocrine Sciences) Labcorp test 501902

This test measures the precise amount of free T4, a thyroid hormone available for your body to use, using a specialized technique that filters out interfering proteins. It helps show whether your thyroid is functioning properly, particularly in complex cases where standard tests might be inaccurate due to pregnancy, severe illness, or medications.