How are FT3 and Haut related?

FT3 (free triiodothyronine) is the active thyroid hormone that regulates metabolism and has direct and indirect effects on the skin. Imbalances in thyroid hormones – both hyperthyroidism and hypothyroidism – can lead to skin changes. In hypothyroidism, the skin often becomes dry, rough, cool, and pale, while hyperthyroidism tends to cause moist, warm, thin skin and increased sweating. Hair loss, brittle nails, and delayed wound healing are also associated with thyroid disorders. However, the TSH self-test offered by MyBody-X only measures thyroid-stimulating hormone, not FT3 or FT4 directly. An abnormal TSH level may indicate thyroid dysfunction that could affect the skin, but a single TSH measurement is insufficient for a skin diagnosis. The evidence for the FT3–skin link comes from clinical endocrinology and is well-established (human-moderate), but no specific studies or PMIDs are provided in the given context. For unexplained skin issues, a physician should perform a comprehensive thyroid evaluation.