Is FT3 useful for Fruchtbarkeit?

Whether FT3 (free triiodothyronine) is useful for fertility requires a nuanced answer. Thyroid hormones are critical for reproductive function in both sexes. Imbalances can disrupt menstrual cycles, reduce egg quality, and impair sperm parameters. However, FT3 alone is not a standard fertility marker. Clinical guidelines typically recommend TSH, fT4, and thyroid antibodies. FT3 may be elevated in subclinical hyperthyroidism or thyroid hormone resistance, which can affect fertility. Low FT3 in the context of non-thyroidal illness (euthyroid sick syndrome) has been linked to poorer IVF outcomes. The evidence is moderate: some studies show associations, but routine FT3 testing is not strongly supported. A full thyroid panel is more informative. Caveat: self-prescribing T3 is risky and should only be done under medical supervision.