What to watch with FT4 and Stress?

FT4 (free thyroxine) is a thyroid hormone that can be affected by stress. Chronic stress activates the HPA axis, which may suppress thyroid function, leading to a condition called 'euthyroid sick syndrome' or low T3 syndrome. In such cases, FT4 may appear normal or slightly elevated while T3 drops. A single FT4 measurement without context (TSH, T3, stress levels, time of day) is of limited value. The provided knowledge context does not contain specific data on FT4 and stress; it focuses on DNA tests and cortisol. Therefore, the evidence level is unclear. Caution: stress can also arise from poor sleep, diet, or mental strain. An abnormal FT4 should always be evaluated by a physician to rule out hyper- or hypothyroidism. MyBody-X tests include FT4 in hormone panels, but interpretation requires medical guidance. Do not rely on a single biomarker; instead, address stress management, sleep, and nutrition holistically.