Díaz Lab Testing Store › Free T3 | Serum (Quest) Image 1 of 1 Free T3 | Serum (Quest) $57.00 The active thyroid hormone — often normal when TSH looks fine but symptoms persist. Add To Cart Added! The active thyroid hormone — often normal when TSH looks fine but symptoms persist. Add-on | Interpretation for Individual Markers $17.00 Add Added!