What role does FT4 play in menopause?

FT4 (free thyroxine) is the active thyroid hormone regulating metabolism. During menopause, declining estrogen levels can indirectly affect thyroid function: estrogen increases thyroxine-binding globulin (TBG), so with less estrogen, TBG decreases, potentially causing a transient rise in FT4 or a shift in the free hormone balance. At the same time, the risk of subclinical hypothyroidism increases because the thyroid becomes less responsive to TSH. However, evidence is mixed: many studies find no consistent change in FT4 across menopause, and symptoms of thyroid dysfunction (fatigue, weight gain) overlap with menopausal symptoms, complicating diagnosis. Routine FT4 screening without clinical signs is not recommended. Caveat: FT4 alone is insufficient – TSH and possibly fT3 should be measured. The evidence is based on observational studies and physiological reasoning, not large RCTs. If symptoms are present, clinical evaluation is warranted.