**NOTE: All laboratory testing requires an authorizing physician. DHA Laboratory offers a patient direct program that partners you with an authorizing physician. If you have any additional questions regarding the availability of testing, please contact our laboratory by telephone or email.**
This test is used when Free T4 may be indicated when TBG (thyroxine binding globulin) problems are suspected. It can also be used to diagnose thyroid disease and screen for hypothyroidism in newborns.