It is estimated that more than 20 million Americans take some form of thyroid hormone replacement for thyroid disease.

The thyroid – a butterfly-shaped gland at the base of the throat – controls the metabolism of many of the body’s systems. An underactive thyroid can cause a number of health problems if left untreated, including unexplained fatigue, weight gain, difficulty with memory, constipation and depression. An overactive thyroid can cause weight loss, rapid heartbeat, excessive sweating and tremors.

Women are at greater risk of developing thyroid disorders. Dr. Robert Smallridge, a Mayo Clinic endocrinologist, says about 80% of all thyroid conditions occur in women. “We do not understand fully why that might be, but it’s well established,” he says. “We also know women suffer from hypothyroidism in particular more often than men.”

Watch: Dr. Smallridge tralks about pregnancy and thyroid issues.

Journalists: Broadcast-quality sound bites with Dr. Smallridge are in the downloads at the end of the post. Please "Courtesy: Mayo Clinic News Network."

Hypothyroidism is a condition in which the thyroid gland doesn't produce enough thyroid hormone.

Although the condition tends to be more common in someone in their 50s, 60s and 70s than early in life, Dr. Smallridge says that, for a small subset of adult women, pregnancy also can cause low levels of thyroid hormone, known as thyroxine or T4.

“About 10% of women are at risk of developing hypothyroidism due to pregnancy. These women have an asymptomatic thyroid condition known as thyroiditis, where an antibody causes a slow destruction of the thyroid gland,” explains Dr. Smallridge.

“Gestational hypothyroidism has been well studied, so young women who have a personal or family history of thyroid disorders would benefit from proactive monitoring during their reproductive life. They should have their TSH (thyroid stimulating hormone) level checked before they conceive and monitored throughout pregnancy,” he says.

Low levels of thyroid hormone can affect many of the body’s systems. “The cholesterol level goes up. The cholesterol can then have an adverse effect on the heart and peripheral vascular system, and it can lead to an increased risk of heart disease and stroke,” says Dr. Smallridge.

Additionally, one Mayo Clinic study found women with untreated hypothyroidism during pregnancy were at higher risk for pregnancy loss, placental abruption, premature rupture of membranes, and neonatal death.

Women are also at risk after delivery as well.

“For some women, up to one year after they deliver, they could develop postpartum thyroid dysfunction — which can create a hyperthyroid state or a hypothyroid state, or one followed by the other,” says Dr. Smallridge.

He recommends women with a history of thyroiditis have their thyroid levels tested at least six to nine months postpartum.

“When we first started studying this condition in the early 1980s, we were finding that a number of women who became very tired, fatigued and had a lack of energy three to four months after having a baby were told their symptoms were due to having a new baby and sent home,” he says. “Now we know that postpartum thyroid issues are significant in terms of quality of life, and women should be aware of it and talk to their doctor about symptoms.”

The post Women’s Wellness: Pregnancy and thyroid disorders appeared first on Mayo Clinic News Network.

June 3, 2011

Dear Mayo Clinic:

What could be causing me to swing back and forth between hypo- and hyperthyroidism?

Answer:
You may be switching between these two disorders for several reasons. Before exploring possible causes, though, it's important that you get a definitive diagnosis of hypothyroidism or hyperthyroidism, if you haven't done so already.

The thyroid, a small gland at the base of the front of the neck, produces hormones that help control body temperature, influence the heart rate, regulate the production of protein and maintain the rate at which the body uses fats and carbohydrates.

An underactive thyroid (hypothyroidism) doesn't produce enough hormone. An overactive thyroid (hyperthyroidism) produces too much hormone. Symptoms may include unintentional weight gain or loss, persistent fatigue, palpitations, and sensitivity to hot or cold temperatures. But because other health problems cause similar symptoms, diagnosing hypothyroidism or hyperthyroidism based on symptoms alone is not possible. Instead, a blood test that measures your level of thyroid hormone is required. If a blood test confirms hypo- or hyperthyroidism and verifies that you have switched between them, there could be several possible explanations.

If you don't have a history of thyroid problems, the most common reason for a change in thyroid function is inflammation of the thyroid gland (thyroiditis). Initially, thyroiditis leads to overactive thyroid function because when the thyroid first becomes inflamed, it releases all its stored hormones. After that, the thyroid slowly begins to return to normal, but it doesn't maintain its usual hormone production. So once the hormone stores are depleted, hypothyroidism develops. Its outcome depends on the type of thyroiditis, as follows.

Two main types of thyroiditis exist. The first, subacute thyroiditis, involves pain that begins at the front of the neck and shoots toward the ears. Subacute thyroiditis is caused by a virus and often resolves on its own, without lasting problems.

The second type, silent thyroiditis, is painless and appears to be an autoimmune disorder, in which the immune system attacks thyroid tissue. Silent thyroiditis is most likely to occur in women during the months following pregnancy. For many people with silent thyroiditis, thyroid function returns to normal after the first episode. This type of thyroiditis can recur, though. If it does, over time people with silent thyroiditis may develop long-term hypothyroidism.

If you're already being treated for a thyroid problem, and your thyroid function begins to shift between underactive and overactive, thyroiditis probably isn't the source of the problem. More likely, your medication is to blame.

People diagnosed with hyperthyroidism usually take the medication methimazole to prevent the thyroid from producing excess hormones. This medication sometimes can initially decrease hormone production too much, and hypothyroidism results. The dose of methimazole then needs to be adjusted and the condition is monitored closely over time.

In people being treated for hypothyroidism, the medication prescribed is often a generic form of the drug levothyroxine. The generic form isn't a problem as long as the same manufacturer's product is used consistently. If the manufacturer changes, the new pill could have a variation of 10 to 15 percent in its active component compared with the prior tablet. That can significantly affect your body, possibly leading to either hyperthyroidism or hypothyroidism. If your pharmacy can't ensure that the generic medication will come from the same manufacturer when you need prescription refills, consider a brand-name drug instead.

Finally, remember that thyroid medication must be taken consistently to ensure your body absorbs it properly. When and how you take thyroid medications, as well as other medications you may take, can impact how effective thyroid medication will be. Follow medication directions carefully, and whenever a new medication is prescribed, discuss with your doctor the impact it may have on your thyroid treatment.

— Marius Stan, M.D., Endocrinology, Mayo Clinic, Rochester, Minn.

The post Could Thyroiditis Be Blamed for Switching Between Hypo- and Hyperthyroidism? appeared first on Mayo Clinic News Network.