was ist ft3 und ft4 — can a microbiome test help?

FT3 (free triiodothyronine) and FT4 (free thyroxine) are the active thyroid hormones in blood, regulating metabolism, heart rate, and body temperature. A microbiome test (e.g., stool analysis) measures gut bacteria composition, not hormones. There is emerging research on the gut–thyroid axis: certain bacteria may influence iodine/selenium absorption or T4-to-T3 conversion. However, the evidence is mostly mechanistic and insufficient to recommend microbiome testing for thyroid assessment. Clinically, FT3 and FT4 are measured via blood tests. A microbiome test might provide indirect clues but cannot replace standard thyroid diagnostics or medical advice.