Which symptom is commonly associated with hyperthyroidism?

Nervousness is a commonly observed symptom of hyperthyroidism due to the overproduction of thyroid hormones, primarily thyroxine (T4) and triiodothyronine (T3). Elevated levels of these hormones accelerate the body's metabolism, leading to increased heart rate, heightened nervous system activity, and feelings of anxiety or restlessness. Individuals with hyperthyroidism might experience an anxious temperament, agitation, or irritability, which are manifestations of the body's heightened physiological state.

In contrast, symptoms like weight gain and cold sensitivity are generally associated with hypothyroidism, where thyroid hormone levels are low and metabolism slows down, often leading to increased sensitivity to cold and weight gain. Dry skin is also more frequently observed in hypothyroidism, where decreased metabolism leads to less oil production and moisture retention in the skin. Thus, nervousness distinctly aligns with the symptoms of hyperthyroidism, illustrating the effects of excess thyroid hormone on the body's systems.