Underactive Thyroid Testing and Treatment

Hypothyroidism, or underactive thyroid, occurs when the thyroid gland fails to produce quantities of the hormones thyroxine and triiodothyronine sufficient to maintain normal chemical reactions in the body. The rate at which these hormones are released is regulated in the pituitary gland and the hypothalamus gland, which produce TSH or thyroid stimulating hormone. TSH signals the thyroid to produce thyroid hormones. 

Symptoms of hypothyroidism include dry skin, feeling tired, hair loss, hoarseness, elevated cholesterol, brittle nails, constipation, depression, increased cold sensitivity and swelling or puffiness in the face. Thyroid disorders are much more common in women over the age of 50. If left untreated, hypothyroidism can cause numerous health issues including weight gain, low blood pressure, painful joints and muscles, infertility and heart disease. These symptoms will typically develop slowly, over a number of years.

There are several potential causes for underactive thyroid, including autoimmune disease, over-treatment of hyperthyroidism, past radiation exposure and certain medications. Autoimmune disease is the most common cause of underactive thyroid and occurs when the immune system begins producing antibodies that attack the body's own tissues. When this occurs within the thyroid, it is know as Hashimoto's thyroiditis. Congenital hypothyroidism is much less common, but is an inherited trait in which the thyroid fails to produce a normal level of hormones, usually from birth onward.

Diagnosing underactive thyroid involves simple blood tests which test thyroid function by checking the level of the hormone in the blood. The test is completed on an outpatient basis and is very simple. A low level of thyroxine combined with a high level of TSH are indicative of underactive thyroid. 
Hypothyroidism is usually treated by taking a daily oral dose of levothyroxine, a synthetic thyroid hormone that will replace the hormones not being produced in the body. At acceptable levels, levothyroxine has no noticeable side effects and is a reasonably affordable medication. Determining the correct dosage of levothyroxine may take some time and additional blood tests will be required to ensure that hormones are at the proper levels. Within 7 to 14 days of beginning treatment, many symptoms will begin to fade. Fatigue will dissipate, cholesterol levels will slowly decline and weight gain will begin to reverse. Treatment for hypothyroidism must continue for life to avoid re-occurrence of symptoms and to protect against additional complications associated with this medical condition.

It is important to consult a doctor if changes are made to the brand or manufacturer of a levothyroxine prescription. Different brands may change the level of hormone in the body and may therefore require medication adjustments to ensure adequate therapy continues. Some foods and drugs can effect the body's  ability to absorb levothyroxine. A high fiber diet, a diet rich in soy products, iron and calcium supplements, some antacids and cholestyramine can all inhibit absorption. It is therefore important to discuss these with a physician when taking thyroid therapy medications.