Name a common sign of hypothyroidism in adults.

Fatigue and lethargy are hallmark signs of hypothyroidism in adults. This condition arises when the thyroid gland does not produce enough thyroid hormones, which play a critical role in regulating metabolism, energy levels, and overall body functioning. As a result, individuals with hypothyroidism often experience a significant decrease in energy levels, leading to feelings of tiredness, fatigue, and a general lack of motivation. This is because the body’s metabolism slows down, impacting not only physical energy but also cognitive function and mood. In contrast, increased energy, weight loss, and rapid heartbeat are typically associated with hyperthyroidism, a condition characterized by an overactive thyroid. Therefore, fatigue and lethargy serve as key indicators of hypothyroidism, highlighting the crucial relationship between thyroid hormone levels and energy levels in the body.