Which condition is characterized by excessive thyroid hormone production?

The condition characterized by excessive thyroid hormone production is hyperthyroidism. This condition occurs when the thyroid gland is overactive and produces an excess of hormones, particularly thyroxine (T4) and triiodothyronine (T3). The increase in these hormones leads to a variety of symptoms, including weight loss, increased heart rate, anxiety, and heat intolerance.

In contrast, hypothyroidism refers to insufficient production of thyroid hormones, leading to symptoms such as fatigue, weight gain, and depression. Cretinism is a severe form of hypothyroidism that occurs in infants due to a lack of thyroid hormones in early development, causing stunted growth and cognitive deficits. A goiter is an enlargement of the thyroid gland, which can occur in both hyperthyroidism and hypothyroidism but is not exclusively indicative of excessive thyroid hormone production.

Thus, hyperthyroidism is the specific condition that illustrates the overproduction of thyroid hormones, making it the correct answer.