What to watch with FT4 and Haut?

FT4 (free thyroxine) is a key thyroid marker. The skin is sensitive to thyroid hormones: elevated FT4 (hyperthyroidism) often causes warm, moist, flushed skin, increased sweating, and acne. Low FT4 (hypothyroidism) leads to dry, rough, pale, cool, scaly skin, with more wrinkles and delayed wound healing. Hair loss and brittle nails are also common. Important: FT4 alone is insufficient for diagnosis – TSH and possibly T3 should be included. Skin changes can have other causes (e.g., eczema, allergies, medications). A MyBody-X test measures FT4 in blood, but interpretation must be done by a physician. The evidence for FT4–skin links is based on clinical practice and endocrine guidelines, not large RCTs. Caveat: reference ranges vary by lab; individual symptoms matter more than isolated lab values.