Free T4 (Thyroxine)
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Evaluation of thyroid function independent of binding protein status. Free T4 levels correlate with T4 secretion and metabolism. In hypothyroidism, FT4 is depressed and conversely, FT4 is raised in hyperthyroidism. Evaluating free T4 levels is useful when altered levels of total T4 occur due to changes in T4 binding proteins, especially TBG.
0.76 - 1.70 ng/dL
* Reference ranges may change over time. Please refer to the original patient report when evaluating results.