Which of the following is a common symptom of hyperthyroidism?

Increased heart rate is a common symptom of hyperthyroidism due to the overproduction of thyroid hormones, which can lead to an increased metabolic rate. The thyroid hormones, particularly thyroxine (T4) and triiodothyronine (T3), are responsible for regulating metabolism and influence nearly every organ system in the body. When these hormones are elevated, they stimulate the cardiovascular system, causing the heart to beat faster and more forcefully. This can lead to palpitations and a sense of heart racing, which are typical for individuals with hyperthyroidism.

The other symptoms you might consider, such as weight gain, cold intolerance, and dry skin, are typically associated with hypothyroidism. In hyperthyroidism, individuals more commonly experience symptoms like weight loss, heat intolerance, and excessive sweating, in addition to the increased heart rate.