What condition is characterized by chronic overproduction of growth hormone?

The condition characterized by chronic overproduction of growth hormone is acromegaly. This disorder typically arises from a benign tumor on the pituitary gland, known as an adenoma, which leads to excessive secretion of growth hormone. As a result, individuals with acromegaly experience gradual, progressive changes in physical appearance, including enlarged hands and feet, facial bone growth, and skin thickening.

Acromegaly commonly occurs in adults after the closure of growth plates, which distinguishes it from gigantism. While both conditions are due to excess growth hormone, gigantism results from growth hormone overproduction during childhood or adolescence before the growth plates have closed, leading to increased height and bone growth overall.

Other conditions listed, such as thyrotoxicosis and Cushing's syndrome, involve different hormones: thyrotoxicosis is related to an excess of thyroid hormones, and Cushing's syndrome is characterized by excessive cortisol levels. Thus, acromegaly is specifically linked to growth hormone, making it the correct answer to the question.