Preferred amount: 1.0 mL Serum
Minimum amount: 0.5 mL Serum
24hrs; Also offered STAT at an additional charge
Centrifuge required?: Yes
In combination with T3 Uptake, T4 is used to help evaluate thyroid gland function; to help diagnose hypothyroidism or hyperthyroidism. T4 is also used to screen for hypothyroidism in newborns.