Hypothyroidism is a chronic condition characterized by low levels of thyroid hormone. If left untreated, hypothyroidism can lead to serious complications.

Hypothyroidism can lead to a range of signs and symptoms, and the main ones include fatigue, cold intolerance, weight gain, depression, slowed heart rate, dry skin, brittle hair, and constipation.

Hypothyroidism is diagnosed primarily through laboratory tests that measure thyroid-stimulating hormone (TSH) and free thyroxine (T4) levels. Additional testing may be performed to identify the underlying cause of the condition.

The primary treatment for hypothyroidism is levothyroxine, a synthetic thyroid hormone, which should be taken 30 to 45 minutes before or at least 3 hours after meals to ensure proper absorption.

Iodine supplements are indicated if hypothyroidism is due to insufficient iodine intake. Although deficiencies in several nutrients have been associated with hypothyroidism, the effectiveness of supplementation for improving symptoms is unclear.

Adequate iodine intake is essential for preventing hypothyroidism, and the recommended daily allowance is 150 µg for nonpregnant adults. A healthy, nutrient-dense diet may help manage the condition, and an anti-inflammatory diet could potentially reduce autoimmune damage in Hashimoto’s thyroiditis.

Thyroid hormone replacement is the primary treatment for hypothyroidism, and its effectiveness generally makes other treatments unnecessary. However, early research is exploring thyroid gland transplantation as a potential way to restore hormone production.

The most common cause of hypothyroidism in the U.S. is Hashimoto’s thyroiditis, and iodine deficiency is prevalent in other countries. Additional causes include certain medications, therapies, and disorders of the pituitary or hypothalamus.