Question

Which of the following statements is not true about thyroxine?
A. Iron is essential for the synthesis of thyroxine
B. It regulates carbohydrates. protein and fat metabolism in the body
C. The thyroid gland requires iodine to synthesize thyroxine
D. Thyroxine is also called thyroid hormone

Answer 1

Hint: Thyroxine is a hormone secreted by the thyroid gland which mainly regulates overall metabolic processes such as carbohydrate and fat metabolism. The thyroxine and triiodothyronine are the only hormones within the body that require iodine for synthesis.

Complete answer:
The thyroid gland situated in the lower portion of the neck produces two major hormones, thyroxine (T-4) and triiodothyronine (T-3). These enzymes play a role in the overall metabolic activity of the body. Thyroxine and triiodothyronine are the only enzymes that require iodine for synthesis. Thyroxine is the more predominant enzyme present within the blood and is secreted 14 times more than triiodothyronine. The major function of the thyroxine enzyme is regulating metabolism. This enzyme acts on every single cell within the body. It is required to increase the metabolic rate which includes, increased protein synthesis, metabolism of carbohydrates and fats, enhanced cellular growth, aid cell division, increased bone growth, and much more.

This hormone also is responsible for improved neural connections within the brain and can also regulate the neural signalling and enhances the activity of chemicals such as dopamine, adrenaline, etc.
Disorders in thyroxine production may cause hyperthyroidism (Grave’s disease) and hypothyroidism (Hashimoto disease), clinical depression, hair loss, and neurodevelopmental disorders.

Thus, the correct answer is option A.

Note: Iron is a crucial component in the production of red blood cells and not in the synthesis of thyroxine. The thyroxine hormone consists of 4 iodine molecules. Hyperthyroidism is a condition where there is excessive production of thyroid hormones and vice versa for hypothyroidism.