What is a classic symptom of hyperthyroidism?

Weight loss is a classic symptom of hyperthyroidism due to the increased metabolic rate that occurs with elevated thyroid hormone levels. In hyperthyroidism, the body experiences an accelerated metabolism, which leads to the breakdown of proteins and fats for energy, resulting in unintentional weight loss despite normal or increased appetite.

Other symptoms commonly associated with hyperthyroidism include increased heart rate, anxiety, tremors, and heat intolerance. These manifestations all stem from the effects of excessive thyroid hormone on the body's metabolism. Weight gain, hypotension, and fatigue are generally associated with conditions of hypothyroidism, where there is a deficiency of thyroid hormones. In that case, metabolic processes slow down, leading to weight gain, lower blood pressure, and fatigue as the body's energy expenditure decreases.