1. What is the thyroid?
The thyroid is a butterfly-shaped gland in the lower portion of the neck, below the voice box, or larynx. It releases two hormones, T3 and T4, which are responsible for controlling the body’s metabolism. The thyroid does not release T3 and T4 on its own, but is controlled by a small gland in the brain called the pituitary. The pituitary releases a hormone called TSH, or thyroid stimulating hormone, which in turn triggers the thyroid to release T3 and T4.
If the thyroid hormone level is high, the pituitary will decrease the amount of TSH that it releases. Conversely, if the thyroid hormone is low, the pituitary will release more TSH, causing the thyroid to release more T4 and T3.
2. What is hypothyroidism?
Hypothyroidism occurs when the thyroid does not produce enough hormones. The majority of hypothyroidism cases occur because the thyroid gland itself is no longer functioning properly; it also happens when the pituitary does not release enough TSH.
Sometimes, medications, iodine deficiency or other diseases can affect the thyroid. Surgical removal of the thyroid or treatment with radioactive iodine for hyperthyroidism (an overactive thyroid) will result in hypothyroidism.
3. What are the symptoms of hypothyroidism?
Symptoms of hypothyroidism can be very vague, but relate to slowing of the body’s metabolism, such as weight gain, fatigue, and cold intolerance.
Other symptoms include:
Hair loss
Thinning of eyebrows
Dry skin and brittle nails
Constipation
Slow heart rate
Mild hypertension
Elevated cholesterol
Lower body temperature
Obstructive sleep apnea secondary to enlarged tongue
Depression
Concentration difficulties
Hoarseness
Body aches
Abnormal menstrual cycles and infertility
Shortness of breath with exertion or decreased exercise tolerance
Very rarely, a life-threatening condition called myxedema coma
4. Who is at risk for developing hypothyroidism?
Approximately 4 percent of the United States population has hypothyroidism. The risk for hypothyroidism is greater for females, the elderly and Caucasians.
5. How is hypothyroidism diagnosed, and can it be treated?
Hypothyroidism is diagnosed by blood tests that measure TSH and/or T4. High TSH indicates hypothyroidism, and then T4 is used to confirm the diagnosis.
Most cases of hypothyroidism require lifelong treatment with thyroid hormone replacement. Physicians will prescribe an oral form of T4 and, occasionally, a combination of T4 and T3. Patients typically begin feeling better after 2-4 weeks of treatment but may require several months before symptoms subside. Dosages are adjusted and monitored every 6 weeks until TSH returns to normal parameters. Once the correct dosage has been found, annual screening is advised.
