Which sign is characteristic of hyperthyroidism?

Weight loss is a characteristic sign of hyperthyroidism due to the increased metabolism that occurs in this condition. Hyperthyroidism results from an overproduction of thyroid hormones, which leads to an increase in the body’s metabolic rate. As metabolism accelerates, the body burns calories more quickly, often resulting in weight loss despite an increased appetite.

In patients experiencing hyperthyroidism, other symptoms might include heat intolerance, rapid heart rate, increased sweating, and nervousness, making it a complex condition with various manifestations. The influence of elevated thyroid hormone levels on metabolism is the primary reason why weight loss is linked to hyperthyroidism, whereas the other options—cold intolerance, brittle hair, and depression—are actually more associated with hypothyroidism, where there is an underproduction of thyroid hormones.