Thyroid

Introduction

Substances in the environment, known as endocrine [ENdoh-krin] disruptors, can alter hormone function. Most research has focused on substances that affect reproductive [ree-pro-DUK-tiv] hormones. However, more than 100 natural and synthetic substances have effects on thyroid function. Because thyroid hormone is needed for the body to develop normally before birth and in early life, anything in the environment that may affect the thyroid is a major concern for pregnant women and infants.

Perchlorate

Perchlorate [per-KLOR-ate] is used in many things, such as rockets, fireworks, road flares, matches, and air bag systems. Some fertilizers contain perchlorate and low levels may also be found in the environment due to natural processes. Perchlorate is present in some drinking water in the United States and worldwide. It has also been found in foods such as lettuce and other produce, wheat, cows’ milk, wine, beer, and multivitamins. At high doses, perchlorate
can block iodine from the thyroid gland. Since iodine is needed to make thyroid hormone, thyroid hormone levels might be decreased with even low-level exposure.

Almost everyone in the United States is likely exposed to perchlorate. In one study, higher levels of perchlorate in the urine was associated with lower blood thyroid hormone levels. However, recent studies in pregnant women have shown no link between being exposed to perchlorate and having a change in thyroid hormone levels. Even though research is ongoing and the effects of low-level perchlorate on the thyroid remain unclear, the Environmental Protection Agency has recently decided to limit perchlorate levels in the US drinking water supply.

Thiocyanate and Cigarette Smoke

Thiocyanate [thigh-oh-SIGH-uh-nate] is a chemical that, like perchlorate, can block the thyroid from absorbing iodine. Thiocyanate is found in cigarette smoke and plant foods such as cassava, cabbage, turnips, broccoli, Brussels sprouts, and cauliflower. Large studies testing the effects of cigarette smoking on thyroid function have had varied results. However, it is known that women who smoke during pregnancy are more likely to give birth to babies with low thyroid hormone levels in their blood. Women in the first trimester of pregnancy have lower thyroid hormone levels when they are smokers vs. non-smokers. A recent study showed that cigarette smoking lowers the amount of iodine in breast milk. This may be related to the thiocyanate in The Thyroid and the Environment By Elizabeth N. Pearce, MD, MSc Dr. Pearce is Associate Professor of Medicine at Boston University School of Medicine. She received her medical degree from Harvard Medical School and a Master of Science in Epidemiology from Boston University School of Public Health. Dr. Pearce’s interests include the sufficiency of dietary iodine in the US, thyroid function in pregnancy and lactation, the thyroid effects of environmental perchlorate exposure and other potential endocrine disruptors, and the cardiovascular effects of subclinical thyroid dysfunction. EMPOWER MAGAZINE • Vol . 4, Issue 1 23 cigarette smoke. Diets high in thiocyanate can be part of the reason someone develops goiter (enlarged thyroid) in parts of the world where there is not enough iodine in the diet.

PCBs

In the past, PCBs were used as coolants and lubricants in transformers, capacitors, and other electrical equipment. Starting in the late 1960s there were concerns about the toxicity of PCBs and their ability to persist in the environment. Due to these concerns, production of PCBs was outlawed in the US in 1979. Although levels of PCBs have decreased, PCBs remain widespread in the environment and the food chain because their presence persists for years. The structure of PCBs is similar to that of thyroid hormone, and they are thought to alter the actions of thyroid hormone in body tissues. Babies exposed to PCBs before birth have lower intelligence. This might be because PCBs interfere with the way thyroid hormone helps the brain develop normally.

Bisphenol-A

Bisphenol [BISS-feh-nol]-A (BPA) is used in food containers, baby bottles, and reusable water bottles, and is found in linings of some metal food cans. It may leach from these containers into stored food and drink. Studies in rats have shown that BPA can block thyroid hormone actions, but this has not been clearly shown in humans.

Triclosan

Triclosan [try-KLO-san] is an antibacterial [an-ti-bak-TEERee-ul] agent that is found in soaps, toothpastes, skin care products, plastics, and fabrics. At high doses in rats, triclosan decrease thyroid hormone levels. Lower-level triclosan
exposure has had varying effects on thyroid hormone actions in frogs. In the only human study, brushing teeth with a triclosan-containing toothpaste for two weeks raised blood triclosan levels, but did not alter thyroid function.

PBDEs

PBDEs have been used as flame retardants in plastics, foams, building materials, carpet, and upholstery. PBDEs are slowly released from these products into the environment. PBDEs have been detected in many foods. Exposure may also come from inhaling indoor air and contact with house dust. In animal studies, PBDE exposure causes low thyroid hormone levels. However, results of the few human studies, to date, have not shown consistent effects of PBDEs on the thyroid.

Isoflavones

Isoflavones [eye-so-FLAY-vones] are found naturally in soy products, peas, beans, nuts, grain products, coffee, and tea. Large doses can decrease thyroid hormone. Infants fed soy formula without enough iodine nutrition may develop low thyroid function. Since all infant formulas marketed in the US now contain iodine, this is not currently a problem. Recently 13 out of 14 studies of the effects of soy or isoflavones on thyroid function in healthy adults showed only a small decrease in thyroid hormones or no effects.

Sunscreens

Studies in rats have shown that ingredients in certain sunscreens may alter the body’s ability to process thyroid hormone. These sunscreen ingredients have been found in wastewater treatment plants, are known to build up in fish, and have been found in human milk. Sunscreens, cosmetics, and diet can expose a person to these thyroid hormone-altering ingredients. In one human study, one week of applying sunscreen with these ingredients to the entire body every day did not alter thyroid function.

Summary

Common environmental exposures such as cigarette smoke may affect thyroid function. People may be most vulnerable to these effects in early life, since thyroid hormone is needed for normal brain development. More studies are needed to better understand the risks.

Dr. Pearce is Associate Professor of Medicine at Boston
University School of Medicine. She received her medical degree from Harvard Medical School and a Master of Science in Epidemiology from Boston University School of Public Health. Dr. Pearce’s interests include the sufficiency of dietary iodine in the US, thyroid function in pregnancy and lactation, the thyroid effects of environmental perchlorate exposure and other potential endocrine disruptors, and the cardiovascular effects of subclinical thyroid dysfunction.

By Jeffrey I. Mechanick, MD, FACP, FACE, FACN, ECNU

Low thyroid function should be considered when someone complains of typical symptoms, such as fatigue, weight gain, constipation, and dry skin. But as you can imagine, these symptoms could also be due to many other causes. So a diagnosis of low thyroid function must always be made by your doctor and generally requires a “TSH” test (See link). The standard treatment for low thyroid function is levothyroxine [le-vo-thigh-ROX-een], a synthetic medicine that is basically the same as the thyroid hormone that your own thyroid gland produces.

From time to time, you may get advice about other ways to treat low thyroid function or hypothyroidism [hie-po-THIGH-roid-is-m]. The source could be the internet, a friend, or even a doctor or nurse. Besides making sure that you actually have low thyroid function, properly diagnosed by your doctor, you should be aware of some important points about the use of dietary supplements that are marketed or claimed to have thyroid-related actions. Bear in mind as you read this that there are no scientific studies showing that dietary supplements actually improve thyroid function in any significant and safe manner. As more research is done, some dietary supplements may show promise, but levothyroxine is still the proven, safe way to treat low thyroid function.

There are three broad types of dietary supplements that you may encounter regarding your thyroid.

Supplements that contain a lot of iodine

Kelp, a type of seaweed, contains a lot of iodine. Kelp may be suggested as a logical and natural way to boost the function of your thyroid. After all, thyroid hormone contains iodine so increasing the amount of iodine in your diet should be good for your thyroid, right? Unfortunately, this is not the case. In fact, a high level of iodine intake may reduce the amount of thyroid hormone secreted or released from your own thyroid gland.

Substances that are claimed to promote thyroid function

B-complex vitamins, garlic, ginger, gingko, licorice, L-tyrosine, magnesium, manganese, meadowsweet, oats, pineapple, potassium, saw palmetto, selenium, tiratricol (TRIAC), and valerian have all been claimed to improve thyroid function. The theory behind many of these claims is attractive and very interesting. However, there is not enough data to support using these substances instead of levothyroxine for the treatment of hypothyroidism or an underactive thyroid.

Animal-derived thyroid extracts or desiccated [DESS-ih-KATE-ed ] thyroid

Desiccated thyroid has been used to treat hypothyroidism for many years, but is rarely taken anymore. Most people switched to levothyroxine by the end of the 1970s. People may also seek out thyroid extract as a treatment for low thyroid function because they prefer “natural” treatments. Though this type of treatment still works by replacing the missing thyroid hormone from the body, it does not provide levels that are either as consistent or easy to monitor as levothyroxine does. In fact, if you search the internet for controlled clinical trials involving low thyroid hormone treatment, you will find a lot of strong evidence for levothyroxine and virtually none for thyroid extract.

So, when it comes to the treatment of any medical condition and specifically an underactive thyroid, the safest and most effective treatments should be used. Remember these key points:

• If you suspect that you have low thyroid function, see your doctor.
• If you truly have low thyroid function, levothyroxine should be used.
• At the present time, there is no proven role for the use of dietary supplements to boost thyroid function.
• If there is any doubt or question about an accurate diagnosis or best treatment for low thyroid function, consult an endocrinologist [en-doh-cri-NA-lo-jist].

Dr. Mechanick is Clinical Professor of Medicine and Director of Metabolic Support in the Division of Endocrinology, Diabetes, and Bone Disease at Mount Sinai School of Medicine in New York City. He has authored over 170 publications in endocrinology and nutrition and edited/authored five books in the fields of diabetes, nutrition, thyroid, and metabolic bone disease. Dr. Mechanick is in private practice in endocrinology and metabolic/nutrition support in New York. He currently serves as Vice President and Treasurer of the American Association of Clinical Endocrinologists (AACE).

Introduction

Thyroid health during pregnancy is very important for both the mother and the fetus (unborn child). During pregnancy the mother’s thyroid hormone crosses the placenta [pluh-SEN-tuh] and is needed for the growth of the fetus. When the mother’s thyroid produces either too little or too much thyroid hormone, serious side effects can occur. So, it is extremely important that during pregnancy the mother’s thyroid is working normally.

During the last 20 years there has been much research on the effect of thyroid disease on the mother and developing child. The research has shown that women may develop thyroid problems for the first time during pregnancy. To promote thyroid health during pregnancy, the American Thyroid Association published guidelines in October 2011 on all aspects of thyroid health during pregnancy (http://thyroidguidelines.net/pregnancy). The guidelines have been carefully reviewed and endorsed by the American Association of Clinical Endocrinologists [en-doh-cri-NA-lo-jists].

What changes happen with the mother’s thyroid gland during pregnancy? Pregnancy can be viewed as a “thyroid stress test.” During pregnancy the thyroid gland must make 50% more thyroid hormone. To do this, the mother also has to increase her intake of iodine (which is needed by the thyroid gland to make thyroid hormone) by 50%. So, the guidelines recommend that all pregnant and breastfeeding women take a daily prenatal vitamin that contains 150 mcg of iodine. This is very important because recent studies suggest that many women of childbearing age in the United States have low iodine levels.

Hypothyroidism (an underactive thyroid )

There are 2 types of hypothyroidism [hie-po-THIGH-roid-is-m]: minimal to mild, which is called subclinical hypothyroidism, and more severe, which is called overt hypothyroidism. Overthypothyroidism can lead to a miscarriage, preterm delivery, decreased IQ in the unborn child, and gestational [jeh-STAY-shun-ull] hypertension (high blood pressure during pregnancy). Subclinical hypothyroidism has also been associated with miscarriage, preterm delivery, and decreased IQ.

Women with hypothyroidism and on thyroid hormone replacement usually need to increase their dose during pregnancy. This is not surprising as their thyroid gland is unable to produce the extra thyroid hormone required during pregnancy. Before getting pregnant, women on levothyroxine [le-vo-thigh-ROX-een] (the typical thyroid-replacement drug) should have their hormone levels checked so their dose can be changed if needed. Pregnant women on this drug need to be checked often during pregnancy. The guidelines recommend how and when to adjust the dose of thyroid hormone, and how often to test the thyroid level during pregnancy.

In addition to women known to be hypothyroid prior to pregnancy, another 2.5% of all pregnant women are hypothyroid. Most of these women have subclinical hypothyroidism and do not have any symptoms. These women are unable to produce the extra 50% of hormone needed during pregnancy because their thyroid has already been partially damaged—usually by the body’s immune system attacking the thyroid gland and damaging it (www.ThyroidAwareness.com/thyroid-conditions). While the ATA guidelines do not recommend treatment in all women with subclinical hypothyroidism, treatment is recommended in women with subclinical hypothyroidism who have thyroid antibodies. This is checked with an easy blood test. A positive test means that a body’s immune system is attacking the thyroid gland. Women who get the test and get the right treatment have less chance for miscarriage and preterm delivery.

Whether or not to screen all women for thyroid disease during pregnancy has been, and remains, hotly debated. There is not much proof that treating pregnant women with subclinical hypothyroidism decreases complications in the mother and fetus. Therefore, the guidelines do not recommend universal screening. However, the guidelines do recommend that screening be done in all women in the following high-risk groups for thyroid disease:

High Risk Groups (not all high risk groups noted)

• Women with a history of thyroid disease or thyroid surgery
• Women over 30 years of age
• Women with symptoms of thyroid disease or with a large thyroid known as a goiter
• Women with type 1 diabetes or any other autoimmune disorder
• Women with a history of miscarriage or preterm delivery
• Women with a family history of thyroid disease
• Women with infertility

Hyperthyroidism (an overactive thyroid )

Hyperthyroidism [hie-per-THIGH-roid-is-m] is also divided into overt and subclinical hyperthyroidism. It is much less common then hypothyroidism, and less than 1.0% of all pregnant women have it. Overthyperthyroidism causes miscarriage, gestational hypertension, eclampsia [eh-KLAMP-see-uh] (also known as toxemia and causes high blood pressure) and preterm delivery. Subclinical hyperthyroidism does not cause any bad outcomes in either the mother or unborn child.

The most common cause of hyperthyroidism during pregnancy is Graves’ disease, which is also an autoimmune disease. Graves’ disease is caused by an antibody in the blood that makes the thyroid gland release too much thyroid hormone. Women with Graves’ disease should see their doctor before getting pregnant to ensure that they are on the appropriate dose of anti-thyroid drugs. Even women successfully treated for Graves’ disease in the past require special monitoring during pregnancy. The ATA guideline offers specific recommendations for treating women with Graves’ disease during pregnancy, including how often to monitor the patient, the optimal drugs to use during the pregnancy, and the safety of breast feeding while on antithyroid medication.

Postpartum Thyroiditis

Postpartum thyroiditis (PPT), another autoimmune condition, is a thyroid disease in the postpartum period in women who typically do not have a history of having a thyroid disorder. Eight percent of all women (or approximately one out of every 12 women) will develop PPT. Women with postpartum [post-PAR-tum] thyroiditis [thigh-roid-EYE-tis] may be diagnosed any time during the first year following childbirth. If the diagnosis is made in the early stages of the condition, an overactive state (too much thyroid hormone, called hyperthyroidism) is more likely. During later stages of the condition, the thyroid runs out of thyroid hormone and becomes an underactive thyroid (too little thyroid hormone, called hypothyroidism). Most women will recover fully and have normal thyroid function at the end of the first year after childbirth. The ATA guidelines provide recommendations for the treatment of both the hyperthyroid and hypothyroid phases. The guidelines also recommend yearly monitoring in women who had an episode of PPT because they are at higher risk for getting permanent hypothyroidism.

Conclusion

Thyroid health during pregnancy is important for the mother and developing baby. All pregnant women should take prenatal vitamins with iodine. Women with pre-existing thyroid disease need special monitoring and treatment during pregnancy. Because both hypothyroidism and hyperthyroidism cause serious side effects, first trimester screening of women at high risk for thyroid disease is recommended.

Dr. Stagnaro-Green graduated from Mount Sinai School of Medicine.
Following a residency in Internal Medicine at New Jersey Medical School he completed a fellowship in Endocrinology and Metabolism at the Mount Sinai School of Medicine. In 2005, he received a Masters of Health Professions Education at the University of Illinois-Chicago. Dr. Stagnaro-Green is an internationally known researcher in the field of thyroid disease and pregnancy. His endocrine research focuses on thyroid antibodies and miscarriage, the relationship between thyroid dysfunction and preterm delivery, and postpartum thyroiditis. Presently he is senior associate dean for education at the George Washington University School of Medicine and Health Sciences where he is Professor of Medicine and Professor of Obstetrics and Gynecology.

Imagine finding out that you have a thyroid nodule, when you thought that all you had was a “*swollen gland” and an upper respiratory infection. For Stacey Thureen, a visit to the doctor turned into the discovery of a nodule on the left side of her thyroid and not a “*swollen gland.” Fear, confusion, and disbelief are some of the immediate feelings that come to mind, right?

Stacey grew up in New Jersey and attended college in Iowa. She worked hard on her double major in English and Communication Studies and also swam competitively for the University of Iowa Hawkeyes. This hard work and dedication led Stacey to the communication and media industry where she currently works on projects for non-profit, print and production outlets. Stacey’s busy career and new diagnosis was daunting, but she knew that with good doctors and a strong support group she could get through this difficult situation.

After Stacey had further testing including a biopsy with a very small needle called a fine needle aspiration, doctors decided the best plan of action was to remove the left side of Stacey’s thyroid gland, also known as a partial thyroidectomy. “When I was told I needed surgery, I remember feeling that I trusted the doctors’ guidance,” Stacey reflects, “I had peace of mind knowing that they were doing everything they could to help me and my overall thyroid health.”

After her surgery on June 10, 2011, Stacey received more news. She had an autoimmune disease known as Hashimoto’s thyroiditis and hypothyroidism. Hashimoto’s thyroiditis is a condition where the body’s immune cells produce antibodies which can damage thyroid cells and cause hypothyroidism when not enough thyroid hormone is being made. This is the most common thyroid disease in the United States and is seven times more common in women than
men. Stacey was immediately put on synthetic thyroid hormone medication to balance out her hormone levels.

This story line probably holds true for many patients whose thyroid glands are not working properly, but Stacey has an added obstacle. Stacey’s family suffered four losses prior to her diagnosis and one loss three days after her surgery.

“My faith and my husband’s support have given me strength through this process,” Stacey says.

She says that her support system of friends and family enabled her to talk about her feelings and fears while going through this difficult time. To anyone else going through similar experiences, whether it is a newly diagnosed disorder or losing a family member, Stacey urges people to talk about it with others. “By sharing your story you find a support system that you did not know existed,” she explains. Stacey discovered that many other women in her life were also affected by thyroid problems. It is comforting for Stacey to know that there are other people going through the same thing as her.

After sharing her story with friends and family, Stacey decided to use her communication and media talents to share her story with the public. She was featured on the show Better Living with Liz Walker, produced by The Walker
Group, LLC. This story showed the journey from discovery to treatment to acceptance of Stacey’s thyroid problem.

Stacey’s advice to other people going through similar situations is simple: “Take it one day and one step at a time. Your support system will help you through anything.”

To learn more about Stacey and her story, or to watch the Better Living with Liz Walker segment, visit www.StaceyThureen.com. To learn more about the thyroid conditions and treatments, visit www.ThyroidAwareness.com.

(*Editor’s Note: A term that is commonly used by the public for enlarged lymph nodes due to upper respiratory infections.)