Triiodothyronine.reverse

Reverse T3 (rT3) is an inactive thyroid hormone produced alongside active T3. Your body converts thyroid hormones (T4 and T3) into either active T3 or inactive rT3, depending on your metabolic needs and stress. High reverse T3 can indicate that your thyroid hormones are being shunted away from active forms, potentially causing fatigue and metabolic slowdown despite normal TSH and T4 levels. This test is useful for investigating persistent thyroid symptoms and understanding how your body is utilizing thyroid hormones during stress, illness, or metabolic imbalance.