Thyroxine (T4)

Fasting Required: No

Specimen: Blood

Results: 1-2 Business Days

Description:
A T4 test measures the blood level of the hormone T4, also known as thyroxine, which is produced by the thyroid gland and helps control metabolism and growth. The T4 test is performed as part of an evaluation of thyroid function. T4 measures the entire amount of thyroxine in the blood, including the amount attached to blood proteins that help transport the hormone through the bloodstream.

Methodology:
Immunoassay (IA)

Limitations:
Nonthyroidal chronic diseases, nicotinic acid and nutrition may decrease results. Thyrotoxicosis may not always cause abnormal results. Binding protein variations may cause variations in results. Increases may be associated with pregnancy or oral contraceptive use.

Reference Range(s):
4.5-12.0 mcg/dL

Clinical Significance:
For diagnosis of hypothyroidism and hyperthyroidism.

Note: Result turn around 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.