Structure
L-Thyroxine, also known as levothyroxine, is a synthetic form of the thyroid hormone thyroxine (T4) with a tyrosine backbone and four iodine atoms.
Chemical Formula: C₁₈H₁₉I₄NO₄
Mode of Action
Thyroid Hormone Replacement: Mimics endogenous thyroxine, binding to thyroid hormone receptors in the nucleus of target cells.
Metabolic Regulation: Enhances basal metabolic rate by increasing oxygen consumption and heat production.
Growth and Development: Essential for normal growth, neurological development, and differentiation in various tissues.
Cardiovascular Effects: Increases heart rate, cardiac contractility, and enhances cardiac output.
Uses
Hypothyroidism: Replaces deficient thyroid hormones to restore normal metabolic function.
Myxedema Coma: Emergency treatment of severe hypothyroidism with life-threatening symptoms.
Goiter: Manages thyroid enlargement by providing negative feedback on thyroid-stimulating hormone (TSH) secretion.
Thyroid Cancer: As part of adjuvant therapy to suppress TSH and inhibit tumor growth.
Scholarly Use: Employed in studies investigating thyroid hormone physiology and metabolism.