Approximately 5% of Americans aged 12 and older are diagnosed with hypothyroidism, which occurs when the body lacks sufficient thyroid hormone.

The thyroid gland, situated in the neck, produces thyroid hormones that regulate metabolism. Chronic hypothyroidism can affect various organs, from the heart to the brain, explains Dr. Shuchie Jaggi, DO, an endocrinology expert and co-director of the thyroid program at Lenox Hill Hospital.

Hypothyroidism can arise from several factors. In rare instances, it can indicate the presence of more serious health conditions, making it crucial to collaborate with your healthcare provider to manage symptoms effectively.

Understanding hypothyroidism

“Hypothyroidism is quite prevalent and tends to become more common as people age,” states Dr. Erik Alexander, MD, head of the thyroid section at Brigham and Women’s Hospital and a professor at Harvard Medical School. “It also appears to be more frequent in women than in men,” he adds.

Symptoms of hypothyroidism can be mild to severe, according to Alexander. This condition often slows down metabolism, causing the body to burn fewer calories than usual, which can lead to weight gain, as noted by the American Thyroid Association.

Other potential symptoms include: severe fatigue, constipation, dry skin, sensitivity to cold, irregular menstrual cycles, difficulties concentrating, and muscle pain, says Jaggi. Importantly, since many of these symptoms might stem from different underlying issues, hypothyroidism is primarily diagnosed through lab tests.

What leads to hypothyroidism?

The most common cause of hypothyroidism is Hashimoto’s disease (also referred to as Hashimoto’s thyroiditis, chronic autoimmune thyroiditis, or lymphocytic thyroiditis), according to the Cleveland Clinic. This autoimmune condition causes the immune system to attack the thyroid, resulting in inflammation and a decrease in thyroid hormone production, as reported by the National Institute for Diabetes and Digestive and Kidney Diseases.

Hypothyroidism can also result from:

• Congenital hypothyroidism
• Partial or complete removal of the thyroid
• Radiation therapy targeted at the thyroid
• Certain medications
• Issues related to the pituitary gland or hypothalamus
• Lack of iodine

Managing hypothyroidism

“Regardless of the severity, hypothyroidism should be assessed by a doctor to understand the prognosis and necessary actions,” advises Alexander. Some cases of mild to moderate hypothyroidism may resolve on their own, especially if linked to thyroid inflammation. However, chronic conditions like Hashimoto’s disease generally require ongoing treatment.

Hypothyroidism is treated using a thyroid hormone replacement medication called levothyroxine, according to Jaggi. Regular blood tests from your healthcare provider can help monitor and confirm when hormone levels have returned to normal, per NHS guidelines in the U.K.

Severe forms of hypothyroidism can pose serious health risks, making it essential to consult with your healthcare provider if you begin to notice significant symptoms, says Alexander. Untreated chronic hypothyroidism can lead to myxoedema, a life-threatening state that may result in coma, warns Jaggi.