Hypothyroidism: Key Q&A

Reviewed By:
Robert Cooper, M.D., FACE

What is the difference between hypothyroidism and hyperthyroidism?

Hypothyroidism is a disorder in which the thyroid gland is not producing enough thyroid hormones to meet the body's needs. Most people with hypothyroidism will need to take synthetic thyroid hormones for life to relieve symptoms and avoid long-term consequences.

Hyperthyroidism, also called overactive thyroid, is marked by an abnormally high level of thyroid hormones in the blood.

If I have hypothyroidism, am I at higher risk for hyperthyroidism?

Treatment of hypothyroidism involves taking medications to increase levels of thyroid hormones. In some cases, this can lead to hyperthyroidism.

To reduce this risk, your doctor will conduct regular blood testing to make sure your thyroid hormone levels are in the appropriate range for you. Still, it is important to report any symptoms of hyperthyroidism to your doctor. This may include:

• Unexplained weight loss
• Nervousness
• Palpitations (pounding heartbeat)
• Weakness, particularly in the upper arms and thighs
• Unusual sweating
• Feeling hot
• Trouble sleeping
• Lighter menstrual periods
• Vision changes
• Difficulty breathing
• Weakness
• Heat intolerance

Is treatment the same for the elderly?

In general, elderly people with hypothyroidism and those with heart conditions are treated conservatively. This is because thyroid hormone increases the oxygen demands of the heart muscle. In elderly people and those with coronary artery disease, thyroid hormone has a small risk of causing abnormal heart rhythms, chest pain or even heart attack.

Is treatment the same during pregnancy?

Pregnant women may require different doses of thyroid hormone and more frequent monitoring. Hypothyroidism can be particularly harmful during pregnancy because it can harm the developing fetus.

How common are the symptoms of hypothyroidism?

In many cases, it can take months or years for low levels of thyroid hormones to produce noticeable symptoms. However, hypothyroidism does affect most of the body's major systems (even when symptoms are not present).

The many possible symptoms include fatigue, weakness, unexplained weight gain, lack of appetite, thinning hair, brittle nails, constipation, joint or muscle pain, puffiness or swelling, memory loss, depression, feeling cold, hoarseness, hypersensitivity of the eyes to light, low sex drive, heavy menstrual flow, longer or more frequent periods and severe menstrual cramps.

What is a thyroid test, and how is it used?

The most common thyroid test is blood testing to measure the levels of several hormones produced by the thyroid gland and one produced by the pituitary gland (thyroid-stimulating hormone, or TSH). The blood sample is sent to a clinical laboratory for analysis. There are also thyroid imaging tests such as a thyroid scan or ultrasound. Thyroid tests are used to diagnose thyroid conditions and to monitor the disorders and their treatment.

How long do most people need to be treated for hypothyroidism?

If you have hypothyroidism you will most likely require lifelong treatment. The most common type of treatment is thyroid hormone replacement. However, there are some types of hypothyroidism that are temporary, as in the case of postpartum thyroiditis, which affects some women after giving birth.

Plus: Get more answers to your questions at the Thyroid Conditions message board.