Which of the following human hormones contains iodine?

Thyroxine, also known as T4 hormone, is the only human hormone that contains iodine in its chemical structure. It is produced and secreted by the thyroid gland, a butterfly-shaped gland located in the front of the neck. Every student must clearly remember that iodine is not just important — it is absolutely essential for the synthesis of thyroxine. Without adequate iodine intake through diet, the thyroid gland simply cannot produce this hormone, leading to serious health problems. Thyroxine plays a central role in regulating the body's metabolism, energy production, and overall growth and development throughout life. This is exactly why iodised salt is strongly recommended in daily diet across the world.

• Iodine Content: Each thyroxine molecule contains exactly four iodine atoms, which is why it is also called T4
• Thyroid Gland: Thyroxine is exclusively synthesised in the thyroid gland using iodine absorbed from food and water
• Metabolic Role: Directly controls basal metabolic rate, body temperature, heart rate, and overall energy levels
• Deficiency Effects: Iodine deficiency leads to hypothyroidism, goitre, stunted growth, and poor brain development in children
• Iodised Salt: Regular consumption of iodised salt ensures adequate iodine supply for healthy thyroxine production