Coupon Codes not valid for this testing. Fasting Required: No Specimen: Blood Lab: Quest Diagnostics Results: Average processing time 2-3 days Note: Result turnaround times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance. Tests Include: T3, Free: Triiodothyronine (T3) - This test is used to evaluate thyroid function. It is primarily used to diagnose hyperthyroidism. It is also used to assess abnormal binding protein disorders and to monitor thyroid replacement and suppressive therapy. T4, Free: Thyroxine T4 (Free) This test is used to evaluate thyroid function in individuals who may have protein abnormalities that could affect total T4 levels. It is used to evaluate thyroid function and monitor replacement and suppressive therapy.