Normally, the thyroid produces two thyroid hormones: thyroxine (T4) and triioxothyronine (T3). These hormones are involved in several different functions of the body, including metabolism. Different conditions can cause the thyroid gland to not produce enough of these hormones; this condition is called hypothyroidism, or an underactive thyroid. Patients with an underactive thyroid can have several different symptoms, which vary due to the severity of the thyroid hormone deficiency.
Getting treatment for an underactive thyroid is important, as several complications from an untreated underactive thyroid are possible. Some of the complications are emergency conditions, such as myxedema coma and suppurative thyroiditis.
MedlinePlus noted that myxedema coma is the most severe type of hypothyroidism. Patients can develop myxedema coma if they have untreated hypothyroidism and are exposed to the cold or if they have an infection or illness.
Certain medications, such as lithium, sedatives and amiodarone, may also cause myxedema coma in patients with an untreated underactive thyroid. Symptoms include a slow heart rate, delirium, urine retention, constipation, seizures and fluid build-up.
Other symptoms include low blood sugar, low blood pressure, decreased breathing, a below normal temperature, stupor and coma. Myxedema coma is rare, but life-threatening. Of all cases, 30 to 60 percent of patients die, according to the University of Maryland Medical Center.
Suppurative thyroiditis, an infection of the thyroid gland, is also a rare and life-threatening complication of hypothyroidism. The condition usually begins with an upper respiratory infection.
Patients may have trouble speaking and swallowing, fever, rash and neck pain. The University of Maryland Medical Center noted that people with Hashimoto’s thyroiditis may have a higher risk.