Hypothyroidism: a women's health issue.

We believe that hypothyroidism should be added to the women's health advocacy agenda. A very common medical condition, hypothyroidism is often undiagnosed and, when diagnosed, is often under-treated. Both lack of treatment and inadequate treatment result in unnecessary suffering and disability for millions of individuals, most of whom are female. (1)

The thyroid gland, located at the base of the neck, produces hormones that regulate metabolism, thereby affecting every organ system in the body. Hypothyroidism occurs when the gland produces an insufficient quantity of hormones; when the bodies' cells are unable to use thyroid hormones; or when the gland is surgically removed. One major cause of hypothyroidism is an autoimmune process in which the immune system attacks thyroid cells; this condition is called Hashimoto's thyroiditis. Other causes include radiation treatment, certain medicines (e.g., lithium), inflammation, too little or too much iodine, pituitary gland dysfunction, and inborn defects of the thyroid. (2) Heredity also appears to play a role. (3) In addition, some industrial chemicals can disrupt the normal functioning of thyroid hormones. These include polychlorinated biphenyls (PCBs) (coolants and lubricants that are no longer legally manufactured but continue to be found in fish, meat, dairy products, and well water (4,5)) and perchlorate (a salt used in explosives and rocket fuel found in drinking water, milk, and certain foods (6)).

Estimates of the prevalence of hypothyroidism in the U.S. differ widely. One professional organization, the American Thyroid Association (ATA), estimates that 12-18 percent of the population is hypothyroid. (2) Thyroid medications are among the most widely prescribed drugs in the U.S.; in 2005, thyroid medications Synthroid and Levoxyl ranked 4th and 24th, respectively, among all brand-name prescriptions filled nationally. (7)

A Women's Health Issue

Women's health advocates should focus on hypothyroidism for several reasons. First, hypothyroidism is disproportionately a woman's disease. The American Association of Clinical Endocrinologists (AACE) estimates that women are five to eight times as likely as men to be hypothyroid. (8) Using this estimate and the ATA prevalence estimate cited above, 2 we calculate that 30-48 million women and girls in the U.S. have hypothyroidism.

Second, hypothyroidism can have serious health consequences for girls and women at all stages of the life cycle. The condition's many symptoms include fatigue, weight gain, depression, sleep difficulties, muscle aches and stiffness, hypertension, high cholesterol, and forgetfulness (see box). Hypothyroidism can delay menarche and cause menstrual problems and early menopause. It can threaten the well-being of both pregnant women and their babies: potential consequences include spontaneous abortion, gestational hypertension, premature delivery, postpartum depression, and impaired cognition in the child. (8-10) For this reason, the AACE recommends that pregnant women be screened for hypothyroidism before pregnancy or in the first trimester. (11)

Hypothyroidism can interfere with work and other productive activities and add stress to relationships. "Anna," a nonprofit executive, describes her experience: "There were times where I couldn't carry my briefcase from the car into the house. I was a CEO of an international organization, and having to stop work would be devastating. I thought about going on disability insurance because I wasn't able to continue my job.... You sense that your entire life has changed, and it's been imposed on the person you married.... Once you lose your normal life, you lose so much."

Third, the large number of undiagnosed cases and widespread undertreatment of the disorder not only harm women's health but also result in a discounting of women's experiences of their own bodies. Both ATA and AACE estimate that half of all cases of hypothyroidism remain undiagnosed, leaving millions of people untreated. (2,8) We believe that this stems, in large part, from the reliance on a single blood test with inconclusive diagnostic criteria.

A hypothyroid diagnosis is typically based on the blood level of thyroid stimulating hormone (TSH). A person with a TSH value higher than a specified cut-off point is defined as hypothyroid, yet controversy exists among endocrinologists over what that cut-off should be. (12-15) In 2002, AACE recommended lowering the cut-off point to 3.0 mlU/L from the higher values typically used by clinical laboratories (4.0-5.5 mlU/L). (16) In 2003, the National Academy of Clinical Bio-chemistry recommended an even lower cut-off value of 2.5 mlU/L. (13) Nonetheless, many clinicians continue to rely on higher cutoff points, limiting accurate diagnosis. Moreover, TSH levels can vary over a day and/or season, and are influenced by a number of variables that include levels of some other hormones. For these reasons, some clinicians believe that the thyroid hormone system is too complex to be measured by a single lab test and may conduct additional testing, e.g., for thyroid autoantibodies and/or levels of the hormones thyroxine ([T.sub.4]) and triiodothyronine ([T.sub.3]) that are available for the body to use (free [T.sub.4] and free [T.sub.3]).

One effect of these disagreements about how to define hypothyroidism is that many women are misdiagnosed and their lived experiences ignored. If a woman whose TSH is within "normal limits" complains of symptoms such as depression, difficulty losing weight, or muscle aches, she may be erroneously treated for depression, fibromyalgia, or other conditions. She may be told that nothing is wrong with her and that her symptoms are "all in her head." "Vanessa," a 47-year-old divorced mother, lived with undiagnosed hypothyroidism for 15 years: "You go in and say 'Test my thyroid,' and the doctor tests your TSH, says you're normal, and sends you out the door. You walk out the door and you just cry because you know you're not feeling normal."

Treatment for Hypothyroidism

Most clinicians use TSH levels to guide their treatment decisions, with the goal of maintaining the TSH value within a given reference range. Women's symptoms may be taken into account, but a woman's experience is often less valued than her TSH level in determining treatment effectiveness.

Treatment for hypothyroidism involves hormone replacement and is not always straightforward. What works for one person may not work for another, and people with the same hormone levels may not have the same degree of symptom relief from a certain regimen. Treatment alternatives include:

* One of the synthetic [T.sub.4] drugs (brand names Synthroid, Levoxyl, Levothroid, and Unithroid; generic name levothyroxine);

* Combination therapy: a synthetic [T.sub.3] drug (brand name Cytomel) plus one of the [T.sub.4] drugs;

* A single drug that includes both [T.sub.4] and [T.sub.3] (brand name Thyrolar);

* Desiccated thyroid, which includes [T.sub.4] and [T.sub.3] and is made from animal thyroid glands (brand names Armour Thyroid, Nature-Throid, and Westhroid).

Thyroid medication can take four or more weeks to stabilize in the body, although some people begin to experience symptom relief soon after beginning medication. For others, finetuning is needed over a period of months for optimal symptom relief. Switching brands sometimes helps; for example, a person who does not do well on one brand of[T.sub.4] medication might feel much better on another.

Some clinicians are unaware of treatment alternatives, including [T.sub.4]/[T.sub.3] combination therapy and desiccated thyroid. Others mistakenly believe that research has shown the [T.sub.4]/[T.sub.3] combination to be ineffective. In fact, only a few studies have compared combination therapy to treatment with [T.sub.4] alone. While limited conclusions can be drawn from these studies due to their small sample sizes and other methodological limitations, results consistently show that the [T.sub.4]/[T.sub.3] combination is at least as effective as [T.sub.4] alone. (17,18)

An Advocacy Agenda

Women who are hypothyroid can be too overwhelmed--or simply too tired--to advocate for themselves. Women's health advocates should be attentive to the damage caused to women's lives by the disorder and work with medical organizations and patient groups to create a climate in which people with symptoms of hypothyroidism are:

* Educated about the diagnosis and treatment of hypothyroidism;

* Encouraged to follow up on symptoms that could be caused by hypothyroidism; and

* Empowered to become experts on their own bodies and to seek clinicians who are knowledgeable about the full range of diagnostic and treatment options.

At the national level, an advocacy agenda should include support for:

* Recognition that symptom relief and improved quality of life are important treatment goals;

* Inclusion of tests for free [T.sub.4], free [T.sub.3], and antibodies in the standard thyroid protocol;

* Reimbursement for the costs of screening women during and after pregnancy and during menopause;

* Recognition of hypothyroidism's role in depression;

* Better understanding of the role of environmental exposures in hypothyroidism; and

* Increased funding for research on thyroid disease with input from women's health advocates on research direction and design.

Working together, women can create a national momentum to broaden the scope of diagnosis and treatment and to help people who suffer from hypothyroidism get accurate diagnoses and regain their lives.

SYMPTOMS OF HYPOTHYROIDISM

People with hypothyroidism may have any of the following symptoms (2,9,19-21)

1. Fatigue; lethargy

2. Sleepiness; sleep apnea; snoring; other sleep difficulties

3. Weight gain, sometimes despite loss of appetite; fluid retention, especially in the face, eyes, hands, ankles, and feet

4. Difficulty losing weight

5. Depression; crying

6. Forgetfulness; memory loss

7. Slowed thinking; poor concentration; "brain fog"

8. Dry skin

9. Dry, brittle hair and nails; hair loss or thinning hair

10. Feeling cold; inability to tolerate cold temperatures ("cold intolerance")

11. Muscle aches, stiffness, and cramps; carpal tunnel syndrome; joint aches

12. Husky or hoarse voice

13. Hearing loss

14. Constipation

15. Enlarged thyroid

16. Heightened sensitivity to medications

17. High cholesterol level

18. Slowed heart rate

19. Hypertension

20. Delayed growth in childhood

21. Delayed puberty; delayed menarche

22. Heavy, frequent, menstrual periods; severe cramps; severe PMS 

23. Infertility; gestational hypertension; miscarriages; premature delivery

24. Early menopause

References for this article are available in the on-line version of the newsletter, or by emailing the editor at [e-mail].

Judy Kaplan, MS, is a public health editor, thyroid cancer survivor, and co-facilitator of a thyroid cancer support group. She was diagnosed with hypothyroidism in her mid-20S.

Jacqueline Horwitz has an MBA and an MA from the Heller School for Social Policy and Management at Brandeis University. She is a medical software professional who became involved in thyroid issues when she was treated for hypothyroidism in 2001. Her research has focused on controversies in hypothyroidism diagnosis and treatment.