was ist ft3 und ft4 — when to see a doctor?

FT3 (free triiodothyronine) and FT4 (free thyroxine) are the active thyroid hormones circulating in the blood. FT4 is secreted by the thyroid gland and converted to FT3 in peripheral tissues; FT3 is the more potent form. You should see a doctor if you experience symptoms like unexplained fatigue, weight changes, palpitations, cold or heat intolerance, or mood disturbances. Also, if a home test (e.g., from MyBody-X) shows abnormal TSH, follow up with a physician for FT3/FT4 measurement. Reference ranges vary by lab, so self-interpretation is unreliable. MyBody-X tests are lifestyle-oriented and not diagnostic. Medical consultation is essential for diagnosis and treatment, especially during pregnancy, when planning pregnancy, or if you have a known thyroid condition.