**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 in the evaluation of thyroid function. Thyroxine is a hormone that plays an integral part in growth and metabolism. It is usually used as a follow-up if one’s TSH results come back as being abnormal.
Patient Preparation: Discontinue any supplements containing Biotin for 72 hours prior to specimen collection.