What is Hypothyroidism?

The thyroid gland is one of the major endocrine (hormone secreting) glands of the body. It is a small gland located near the Adam’s apple and shaped like an “H”. Unless enlarged, it can barely be felt or seen. The thyroid gland secretes hormones that adjust the body’s metabolism. Your metabolism controls the speed at which chemical processes occur in the body, which affects many functions such as heart rate, temperature, and stamina/energy. The element iodine is needed to produce the two thyroid hormones, thyroxine (T4) and tri-iodothyronine (T3). The release of T4 and T3 is dependent on a hormone called TSH (thyroid secreting hormone).

 What are the Risk Factors for Hypothyroidism?
In the U.S., between 7 and 10% of the population over the age of 55 are affected by a thyroid disorder, with Caucasians more commonly affected than African-Americans. Females are 5-8 times more likely to have a thyroid disorder compared to men.

Hypothyroidism can be due to a variety of causes, including history of thyroid radiation, treatment for an overactive thyroid (Graves disease), removal of thyroid gland, and certain medications, such as lithium, amiodarone and iodine. The most common cause of hypothyroidism is a medical condition called Hashimoto’s thyroiditis.

What are the Symptoms of Hypothyroidism?
The symptoms of hypothyroidism can initially be very insidious. Some studies have found only 25-70% of elderly showing typical symptoms. A clinical exam does not establish the diagnosis in many cases. In fact, only 10% of patients with confirmed hypothyroidism were identified on a physical exam. The most important aspect of hypothyroidism is to be very cognizant regarding the subtle signs and symptoms that may develop. Alerting your physician to these signs and symptoms would allow laboratory testing to confirm the diagnosis.

Common symptoms include:

• dry skin
• hair loss
• cold intolerance
• confusion
• difficulty in concentrating
• constipation
• fatigue
• sluggishness
• hoarseness
• depression
• muscle cramps
• weight gain
• menstrual irregularities

How is Hypothyroidism Diagnosed?
The best test to aid in the diagnosis of hypothyroidism is a TSH blood test. The American Thyroid Association recommends testing all patients if suspicious symptoms. Many physicians feel routine screening in women is prudent. The American College of Ob/Gyn recommends screening only high risk women, while the American Thyroid Association recommends screening women every 5 years after 35 years of age.

How is Hypothyroidism Treated?
Once the diagnosis of hypothyrodism is made, the preferred medication is levothyroxine (Synthroid, Unithroid). Levothyroxine mimics exactly the action of the thyroid hormone in your body, therefore acting as a thyroid replacement. The amount of levothyroxine necessary for full replacement of the thyroid decrease with age. Full replacement dose is 110 micrograms per day, although the usual starting dose is 25 – 50 micrograms per day. Excess thyroid replacement is associated with anxiety, fatigue, muscle dysfunction, bone mineral loss, and cardiac problems.

Absorption of levothyroxine may be hampered if taken with some vitamins and medications such as iron, antacids, cholestyramine, calcium carbonate, and sucralfate. Often, small adjustments in dosing is required and may take several months to achieve adequate dosing, therefore patience is required. Often, a repeat TSH test is performed 6-8 weeks after making a dosage adjustment in thyroid medication.

What effect does Menopause have on Hypothyroidism?
Since women are more commonly affected with hypothyroidism and the incidence of hypothyroidism increases with age, it is important to understand the implications of menopause on the thyroid. Symptoms for both hypothyroidism and menopause commonly occur and include depressed mood, decreased energy and decreased memory. If one assumes these symptoms are related only to menopause, then a delay in the diagnosis of hypothyroidism can occur.

A study revealed that women being treated for hypothyroidism were shown to have increased requirements when started on estrogen. Estrogen may increase the need for levothyroxine by altering the binding of hormone in the body. Thirty nine percent of women showed a need for dosage adjustment after starting estrogen. Therefore, measurement of TSH approximately 8 – 12 weeks after starting or stopping estrogen is prudent.

Lastly, there is a concern for women using soy protein for menopause symptoms and taking levothyroxine. Soy protein may inhibit the absorption of levothyroxine. Alerting your physician to long term soy protein use in your diet.