Does routine thyroid screening of adults (especially women) fit into a 2020’s model of cost-efficient, quality healthcare? During the last decade, the delivery, quality, and cost of healthcare in America have been controversial subjects of discussion and debate.
While the public, government, medical, and insurance sectors argue over the best ways to provide quality healthcare at a reasonable price for all Americans, most agree that, in general, preventive services offer one of the most effective ways to control costs and provide the best care possible.
One aspect of preventive medicine involves the early identification and treatment of disease by screening selected populations. Screening is performed on apparently healthy individuals who are asymptomatic (do not have or may not recognize that they have symptoms of a disease).
It differs from case finding, which involves examining and testing patients who do describe symptoms they are experiencing. The goal of screening is to distinguish, in a reliable and valid manner, individuals who may have a disease from those who probably do not.
Thyroid Screening Criteria
If screening for thyroid disease is to be valid it should follow generally accepted principles of any good screening program.
The disease should be recognized as a significant health problem.
According to the report prepared by the U. S. Preventive Services Task Force, hypothyroidism and hyperthyroidism “account for considerable morbidity [disease],”affecting 1% to 4% of the adult and adolescent population (approximately 10,000,000 people). Every year 350,000 to 800,000 new cases are reported. Hypothyroidism is more prevalent among women and people with Down’s syndrome.
Since thyroid dysfunction can affect a variety of systems, including the cardiovascular, nervous, and gastrointestinal, both the health and behavior of patients can be adversely altered. Thyroid dysfunction can result in infertility, miscarriage, and stillbirth. Deaths from hypothyroidism are uncommon, but can occur among patients who develop myxedema coma – a condition resulting from severe, untreated hypothyroidism.
The natural course of the disease should be well understood.
The signs, symptoms, causes, and course of hypothyroidism are well documented. Signs and symptoms generally appear within a few months of the onset of the disease. However, these signs and symptoms are not specific; that is, they can also be the signs and symptoms of other diseases.
Diagnosing hypothyroidism can be more difficult among certain groups of people, delaying treatment and risking complications. For example, the fatigue, dry skin, constipation, and poor memory typically seen in hypo- thyroid patients can be mistaken or dismissed as signs of aging.
Approximately 5% to 10% of the women who have recently given birth develop postpartum thyroiditis; however, the fatigue often associated with this disorder can be incorrectly attributed to stress brought on by a change in lifestyle or lack of sleep.
Subclinical hypothyroidism, or mild thyroid failure, is characterized by a high TSH level and normal thyroid hormone (T4 and T3); patients with this condition are usually unaware of any symptoms (see Mild Thyroid Failure in the Spring 1999 edition of The Thyroid Connection). Approximately 6% to 11% of adult women and 3% of adult men can be classified as subclinically hypothyroid.
According to the U.S. Preventive Services Task Force, 2% of patients with elevated TSH levels will eventually develop overt hypothyroidism. When thyroid antibodies are also present in their blood, the likelihood of developing overt hypo-thyroidism increases—5% to 7% of younger patients and 20% to 24% of older patients within a few years. Some studies have shown that mild thyroid failure is associated with elevated cholesterol levels, impaired heart function, and neuropsychological impairment.
The treatment for the disease should be effective and decrease a patient’s suffering.
The treatment of choice for hypothyroidism is levothyroxine, a relatively inexpensive synthetic thyroid hormone. In most cases, one pill daily is required over the patient’s lifetime. Relief of symptoms can begin within six to twelve weeks, and, with adequate thyroid hormone replacement, proper thyroid hormone levels are restored and maintained after three to six months.
There are very few side effects as a result of levothyroxine treatment. Over-administration of the medication can lead to symptoms of hyperthyroidism and could increase the risk of developing osteoporosis. However, this risk can be avoided with regular monitoring of TSH levels.
The screening tests and any follow-up diagnostic test should be valid and reliable.
Measurement of TSH is the single most accurate test of thyroid function. In recent years, sensitive TSH assays (laboratory tests) have proven highly accurate and less likely to be affected by medical conditions or medications that can create false-positive results. Follow-up of patients with abnormal TSH findings generally includes physical examination and measurement of thyroid hormones.
The cost benefit of early detection, including follow-up diagnostic tests and treatment, should be considered in relationship to the entire healthcare system.
Dr. Paul Ladenson of Johns Hopkins and co- author of Screening for Mild Thyroid Failure at the Periodic Health Examination: July 24/31, 1996, edition of the Journal of the American Medical Association (JAMA) states that in the United States “one out of every $7 is spent on healthcare.” With a renewed interest in holding down medical costs, every dollar spent must be justified.
When determining the benefits of a screening program, it is useful to think of patient benefits in addition to the actual money spent on screening, follow-up tests, and treatment (see Dr. Ladenson’s article The Cost-Effectiveness of Screening for Hypothyroidism on page 5).
The authors of Screening for Mild Thyroid Failure at the Periodic Health Examination estimated the cost to evaluate symptoms common to thyroid disease (fatigue, cold intolerance, dry skin, constipation, depression, and impaired mental processing) to be $160 per symptom before the results of thyroid testing.
In addition, the study concluded that if periodic screening for mild thyroid failure was performed on the same population (adults 35 years of age and older) and at the same time intervals (every five years) as the cholesterol screening recommended by the U.S. Preventive Services Task Force, the cost of thyroid cancer screening compared favorably to the cost of other well-recognized screening programs, such as mammograms for breast cancer.
A policy of who to screen and who to treat should be established in advance of initiating a screening policy.
At present, there are no official guidelines for thyroid screening. While some organizations caution physicians to be suspicious of symptoms in certain populations, they stop short of recommending routine screening.
Populations at increased risk for thyroid disease are older adults (especially women), people with Down’s syndrome, and postpartum women. Dr. Ladenson’s article suggests that screening all adults beginning at 35 years of age or older would be reasonable.
Once diagnosis is confirmed, all in the medical profession strongly recommend treatment of overt hypothyroidism. No one questions the cost effectiveness or cost benefit of treatment. There is less consensus among professionals concerning the treatment of patients who are diagnosed with mild thyroid failure. The decision to treat mild thyroid failure tends to be made on a case-by-case basis.
Screened individuals who appear to have a disease should be given explanations or educational materials concerning the disease to encourage their follow-up examination(s).
Screening for hypothyroidism can be the first step in diagnosing hypothyroidism, but it cannot replace the importance of physicians and other healthcare practitioners performing a physical examination that includes a thyroid palpation (evaluation of the size, texture, and tenderness of the thyroid gland by touching and pressing the patient’s throat).
Various professional and lay organizations as well as pharmaceutical companies provide a variety of free thyroid patient education materials. You can obtain these materials by requesting them from these organizations or by visiting several web sites on the Internet.
Brochures are also available in many physicians’ offices and health clinics. Understanding hypothyroidism and the consequences of not treating it is a key factor in following up on further thyroid testing and adhering to the prescribed treatment.
Current Thyroid Screening Policy for Newborns
Screening newborns for congenital hypothyroidism is one form of early detection that is almost universally accepted and, indeed, is mandatory in North America.
On the other hand, no major medical organization currently recommends screening all asymptomatic adults for thyroid dysfunction. In 1994 the U. S. Preventive Services Task Force summed up its reasons for not recommending routine thyroid screening as follows:
• the low prevalence of unsuspected thyroid disease in healthy people
• a lack of evidence that treatment of subclinical thyroid disease results in significant health benefits
• potential adverse effects of treatment
Since the publication of Screening for Mild Thyroid Failure at the Periodic Health Examination in the July 24/31, 1996 edition of the Journal of the American Medical Association (JAMA), many healthcare providers have begun to re-examine their policy regarding this issue.
Based on the results of their study, the authors concluded that it is cost effective to routinely and periodically measure the TSH beginning at age 35 to detect mild thyroid failure.
Dr. Steven Sherman, Medical Director of The Thyroid Society, routinely recommended this periodic TSH screening in his lectures to primary care physicians.
Reflecting the conclusions of the JAMA article, the American Thyroid Association (ATA), the medical organization for thyroidologists, is considering adoption of a similar policy on TSH screening.
With the current emphasis on controlling medical costs, proponents of routine thyroid screening will have to justify the costs and demonstrate significant health benefits of the program. It is possible that further investigation of the effects of early detection and treatment, especially of subclinical thyroid disease, will be necessary before medical organizations and agencies revise their policy regarding routine thyroid screening.
In addition, policy makers, insurance providers, and healthcare administrators must be convinced of the value and benefits of thyroid screening before they agree to cover the cost of screening.
As the public becomes aware of the issue and learns more about the benefits of routine thyroid screening, they will decide if the costs and benefits are worthwhile for them.
If public pressure grows in support of routine thyroid screening, it can become a catalyst for change.
Current Thyroid Screening Policies by various Organizations
U. S. Preventive Services Task Force
“Routine screening for thyroid disease with thyroid function tests is not recommended for asymptomatic children or adults. There is insufficient evidence to recommend for or against screening for thyroid disease with thyroid function tests in high-risk patients, but recommendations may be made on other grounds. Clinicians should remain alert to subtle symptoms and signs of thyroid dysfunction when examining such patients.”
American Thyroid Association
“… tests of thyroid function should not be part of multiphasic screening for patients who are not suspected to have thyroid disease, except in certain high-risk populations. Suspect populations include the newborn, for whom screening for congenital hypothyroidism of females is mandatory; individuals with a strong family history of thyroid disease; elderly patients; postpartum women 4 to 8 weeks after delivery; and patients with autoimmune diseases such as Addison’s disease and type I diabetes mellitus.” This policy is under currently under review.
American Association of Clinical Endocrinologists
AACE does not have a policy regarding screening for thyroid disease. Guidelines for the evaluation and treatment of hyper- and hypo-thyroidism can be found at their website.
American Academy of Family Physicians
With the exception of newborns, the Academy does not recommend TSH screening for thyroid disease in patients less than 60 years old. However, they are in the process of reveiwing their current statement.
American College of Physicians
“Women over 50 years of age are at special risk for thyroid disease and should undergo periodic TSH screening.”
American College of Obstetricians and Gynecologists
“…recommends screening annually, or as appropriate, for women age 19 and older who are high risk. High-risk is defined as “strong history of thyroid disease; autoimmune disease (evidence of subclinical hypothyroidism may be related to unfavorable lipid profiles).”