How are FT3 and menopause related?

The relationship between free triiodothyronine (FT3) and menopause is complex and not fully established. During menopause, estrogen levels decline, which can influence the hypothalamic-pituitary-thyroid axis. Some studies report a slight increase in FT3 during perimenopause, others a decrease or no significant change. Individual variability is high, influenced by age, BMI, thyroid autoimmunity (e.g., Hashimoto's), and lifestyle. Additionally, the conversion of T4 to T3 changes with age. A direct causal link between FT3 and menopausal symptoms is not proven. MyBody-X hormone tests provide a snapshot but do not replace medical evaluation for symptoms. The evidence level is moderate – human studies exist but no uniform guidelines.