1. What is the thyroid?
The thyroid is a butterfly-shaped gland that resides in the lower portion of the neck below the voice box or larynx. It releases two hormones called T3 and T4, which are responsible for controlling the body’s metabolism. The thyroid does not just release a certain amount of 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 then 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 of its hormones. The majority of hypothyroidism cases are because the thyroid gland itself is no longer functioning properly, but also occurs 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% of the United States population has hypothyroidism. The risk for hypothyroidism is greater for females, increased age, and Caucasians.
5. How is hypothyroidism diagnosed and can it be treated?
Hypothyroidism is diagnosed by blood tests that measure TSH and/or T4. If the TSH is high it 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.
