2026 Dunphy Endocrine and Metabolic Problems Complete Practice Test

In cases of hyperthyroidism, there is an excessive production of thyroid hormones due to overactivity of the thyroid gland. Thyroxine (T4) is one of the primary hormones produced by the thyroid, and its levels are typically elevated in hyperthyroidism. The overproduction of T4 leads to an increased metabolic rate, which can manifest in various symptoms such as weight loss, increased heart rate, and anxiety.

Thyroid-stimulating hormone (TSH) usually decreases in hyperthyroidism, as the pituitary gland senses the high levels of circulating thyroid hormones and subsequently reduces TSH production. Cortisol, which is involved in stress response and metabolism, is not directly affected by thyroid hormone levels in this context, and insulin relates to glucose metabolism rather than thyroid function. Thus, the elevation of thyroxine (T4) is the hallmark of hyperthyroidism, making it the correct answer.