What is Underactive thyroid (hypothyroidism)?

Hypothyroidism occurs when the thyroid gland doesn't produce enough thyroid hormone, slowing down the body's metabolism. It's often caused by an autoimmune condition (Hashimoto's thyroiditis), though it can also result from thyroid surgery, radiation treatment, or certain medications.

Common symptoms include fatigue, weight gain, feeling cold, dry skin, hair thinning, low mood, and constipation. Symptoms often develop gradually, which can make them easy to overlook or attribute to other causes.