How is hypothyroidism characterized?

Hypothyroidism is characterized by the underproduction of thyroid hormones, specifically thyroxine (T4) and triiodothyronine (T3). These hormones are crucial for regulating various bodily functions, including metabolism, energy production, and overall homeostasis. When the thyroid gland is underactive, it fails to produce sufficient amounts of these hormones, leading to a variety of physiological changes.

Patients with hypothyroidism may experience a slowdown in metabolic processes, resulting in symptoms such as fatigue, weight gain, cold intolerance, and depression. This underactivity of the thyroid can also affect the body's ability to maintain normal cholesterol levels, regulate heart rate, and even influence psychological well-being. Therefore, the defining aspect of hypothyroidism is indeed the inadequate production of thyroid hormones.