Hypothyroidism means the thyroid gland is underactive and does not make enough thyroid hormone for the body's needs.
Common symptoms
Symptoms can include fatigue, weight gain, feeling cold, dry skin, constipation, slow heart rate, hair thinning, heavy periods, depression-like symptoms, or brain fog.
Why it happens
Common causes include autoimmune thyroid disease, thyroid surgery, radiation, some medicines, iodine-related issues, or thyroid inflammation.
Hypothyroidism is usually identified with blood tests, because symptoms can be subtle and overlap with many other conditions.