Hyperthyroidism is defined as which?

• A. Autoimmune destruction of the thyroid causing hypothyroidism.
• B. Underproduction of thyroid hormones.
• C. Pituitary tumor causing hyperprolactin.
• D. Overproduction of thyroid hormones with increased metabolic rate.

Answer: (D)

Hyperthyroidism means the thyroid gland is producing too much thyroid hormone, leading to an increased metabolic rate throughout the body. Thyroid hormones (T3 and T4) regulate how fast the body uses energy; when they’re in excess, heart rate, heat production, and overall metabolism speed up. This is why symptoms often include weight loss, heat intolerance, tremors, and rapid pulse.

The other descriptions point to conditions with low thyroid activity or a different pituitary problem. Autoimmune destruction of the thyroid causing hypothyroidism reduces hormone levels, not increases. Underproduction of thyroid hormones is also hypothyroidism. A pituitary tumor causing hyperprolactin elevates prolactin and affects reproductive signaling, not thyroid hormone production.