1. Hypothyroidism
Randi Schutz

2. The Thyroid Gland that regulates metabolism
Located in the front of the neck just below the voice box (larynx)
The thyroid gland releases two hormones: thyroxine (T4) and triioxdothyronine (T3)
The thyroid gland, as well as the pituitary gland and hypothalamus, control how much of these hormones are produced
There are three types of hypothyroidism: primary, secondary, and tertiary

3. Primary Hypothyroidism
Due to a defect in the gland, the thyroid cannot make enough T3 and T4
The most common cause of primary hypothyroidism in the United States is the destruction of the thyroid gland by the immune system (Hashimoto’s thyroiditis)
Other causes of primary hypothyroidism include:
certain drugs such as lithium
radiation exposure to the neck
radioactive iodine used for treatment of hyperthyroidism
special x-ray dyes
surgical removal of part or all of the thyroid gland
some women develop after pregnancy (postpartum thyroiditis)

4. Secondary & Tertiary Hypothyroidism
In secondary hypothyroidism the thyroid gland produces too little hormone due to disorders of the pituitary gland (i.e. pituitary hypothyroidism)
Tertiary hypothyroidism is caused by disorders of the hypothalamus
Pituitary hypothyroidism is a very rare condition where damage to the pituitary gland damages cells that secrete TSH (thyroid stimulating hormone) which stimulates the thyroid to produce normal levels of thyroid hormone

5. Risk Factors Age (older than 50) Female gender Obesity Thyroid surgery
X-ray or radiation treatments to the neck

6. Early Symptoms Cold intolerance Constipation Depression Fatigue
Weakness
Muscle or joint pain
Paleness
Thin, brittle hair and fingernails
Dry, itchy skin
Weight gain and water retention

7. Late Symptoms Decreased sense of taste and smell Dry flaky skin
Hoarseness
Menstrual disorders
Puffy face, hands, and feet
Slow speech
Thickening of skin
Thinning of eyebrows

8. Exams and Tests Physical examination may reveal:
Smaller than normal thyroid gland (but sometimes may also be normal in size or enlarged)
Coarse facial features
Firm swelling of arms and legs
Loss of the edges of eyebrows
Low blood pressure
Slow heart rate
Low temperature
Pale, yellow, and dry skin
Slow muscle relaxation when reflexes are tested
Thin, brittle hair
Chest x-ray may show enlarged heart

9. More Exams and Tests Laboratory tests include:
High levels of thyroid stimulating hormone (TSH) indicate that the thyroid is not producing sufficient levels of thyroid hormone (mainly T4). TSH does not diagnose secondary and tertiary hypothyroidism.
Low free T3 and T4
Total T3 and T4
Anemia on a complete blood count
Increased cholesterol levels
Increased liver enzymes
Increased serum prolactin
Low serum sodium
TSH stimulates the thyroid to produce normal amounts of hormone, TSH secreted by pituitary gland – so damage to pituitary gland causes high TSH (very rare)

10. Treatment Treatment is to replace the thyroid hormone that is lacking
T4 is used most often, but a combination of T4 and T3 is also used
Receive the lowest dose that relieves symptoms and brings blood tests to a normal range
Periodic monitoring of TSH levels Requires life-long therapy, can be completely controlled with early treatment

11. Related Complications
Myxedema coma, the most severe from of hypothyroidism (rare)
Signs and symptoms include: low temperature, decreased breathing, low blood pressure, low blood sugar, and unresponsiveness
Depression
Heart disease
Increased risk for infection
Infertility
Miscarriage
Pituitary tumors
Complications from too much thyroid hormone replacement:
Atrial fibrillation
Osteoporosis
Symptoms of hyperthyroidism

12. References
Holt, Elizabeth H. "Hypothyroidism - primary." Medline Plus N.p., 17 June Web. 4 Dec <
"Hypothyroidism." American Association of Clinical Endocrinologists N.p., Web. 4 Dec <
"Hypothyroidism." Wikipedia N.p., 21 Nov Web. 3 Dec <
Simon, Harvey. "Hypothyroidism." University of Maryland Medical Center N.p., 21 May Web. 4 Dec <