Updated August 18, 2014.
The American Association of Clinical Endocrinologists (AACE) and the American Thyroid Association (ATA) convened a task force on hypothyroidism in adults. The result was jointly published in 2012 in the journals Thyroid and Endocrine Practiceas Clinical Practice Guidelines for Hypothyroidism in Adults (The "Guidelines.") These Guidelines are reviewed here at About.com in the article 2012 Hypothyroidism Guidelines Published.
Who were the authors? The task force includes some of the most well-known, but old-school, conservative endocrinologists, including Jeffrey Garber, Rhoda Cobin, Hossein Gharib, Peter Singer and others. (It is worth noting that some of the task force members have in the past had financial ties to the thyroid drug Synthroid, and seem to take turns running the various thyroid-related professional organizations in recent years.)
The report really can be summed up three conclusions made by the task force:
- Thyroid Stimulating Hormone (TSH) is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations.
- The standard treatment is replacement with levothyroxine (T4).
- The decision to treat subclinical hypothyroidism, when the serum TSH is less than 10 mIU/L, should be tailored to the individual patient.
Here's a look at some of the more controversial recommendations.
Reliance on the TSH Test
The Guidelines state that "Thyroid Stimulating Hormone (TSH) is the single best screening test for primary thyroid dysfunction for the vast majority of outpatient clinical situations."
The Guidelines do not, however, address the significant concerns about the accuracy of the TSH test. Richard Shames, M.D., a California-based practitioner who has written a number of books on thyroid disease, feels that the handling of the samples for TSH tests may result in inaccuracies:
"...the blood that is drawn in the morning at almost every lab in the US is usually not run through the machinery for analysis until that evening. During that time, your hormones - especially the important TSH - may end up showing lower on your test result than is accurate for you. TSH is also a pituitary hormone that, according to the best standards, should be refrigerated properly once drawn. Most big labs have blood samples couriered to them. Are these kept at exact proper temperature? Hardly ever. TSH serum is rarely refrigerated."The Guidelines also rule out the measurement of T3, or use of T3 as a treatment, saying: "Measurement of total triiodothyronine (T3) or Free T3 should not be used to diagnose hypothyroidism."
Reliance on the TSH test -- and exclusion of the Free T3 test -- also ignores the fact that T3 is the active thyroid hormone at the cellular level. Adequate T3 levels require sufficient levels of circulating T4, as well as effective conversion of T4 to T3 in the thyroid gland and peripheral tissues. Integrative practitioners typically measure Free T4 and Free T3 in order to assess the levels of circulating hormone, and assess whether conversion is effective, and seek to optimize the hypothyroidism treatment, using these levels in addition to the TSH test.
The Guidelines also suggest that "except for pregnant women, the evidence does not support specific TSH target values within the normal reference range."
This contradicts the experience of many patients, and the ongoing practice of many integrative physicians, who seek to optimize Free T4 and T3 levels, along with TSH, and address elevated Reverse T3 levels, in order to achieve maximum symptom relief while safely providing thyroid hormone replacement.
Perhaps the most controversial of the recommendations are in the area of treatment, where the Guidelines state that "patients with hypothyroidism should be treated only with levothyroxine drugs. They go on to say that "the evidence does not support using levothyroxine-plus-T3 combinations to treat hypothyroidism."
In making this recommendation, the task force chose to ignore a number of studies, including the 2009 Danish study, published in the prestigious European Journal of Endocrinology, which found that when TSH levels are kept consistent, a T4/T3 combination therapy was superior to levothyroxine-only treatment, when evaluating for a number of quality of life measurements, depression and anxiety scales, and patient preference.
The Guidelines also state: "There is no evidence to support using natural desiccated thyroid hormone -- i.e., Armour, Nature-Throid -- in preference to levothyroxine in treating hypothyroidism." The Guidelines conclude that "therefore desiccated thyroid hormone should not be used for the treatment of hypothyroidism."
The Guidelines are worded in a somewhat disingenuous way on this topic. There haven't been studies that compare levothyroxine only treatment, to treatment with natural desiccated thyroid drugs. So yes, there is no evidence to support their use. But there is no evidence that demonstrates that levothyroxine-only treatment is superior to natural desiccated thyroid. Several million prescriptions for natural desiccated thyroid are written each year, and the number of patients taking these drugs, and practitioners prescribing them, is on the rise. Many patients report anecdotally that they feel better on a natural desiccated thyroid, compared to levothyroxine, and there are a number of practitioners who have found natural desiccated thyroid effective with a subset of their patients. Unfortunately, the Guidelines, in dismissing use of T3 and natural thyroid drugs, without any research that proves the alternative to be superior, is maintaining a status quo that is not serving some patients with hypothyroidism.
The Guidelines state that screening for hypothyroidism should be considered only in patients over the age of 60, and "aggressive case-finding" -- basically, looking for hypothyroidism in people who have risk factors, family history and/or symptoms -- should be considered in those at increased risk for hypothyroidism. The controversy over thyroid screening which has been raised by the Guidelines is discussed at greater length in Why Do Experts Disagree on Thyroid Screening?
Thyroid and Weight Gain
It is interesting that in the introduction to the Guidelines, the most common symptoms of hypothyroidism are listed as: "dry skin, cold sensitivity, fatigue, muscle cramps, voice changes, and constipation..." (Two of the three symptoms that patients most often complain about -- weight gain and depression -- are not included in this list.)
The Guidelines imply that weight gain is not an issue for thyroid patients, and is due to lifestyle issues, and not to fundamental metabolic changes that result from hypothyroidism. This is surprising, as weight gain is one of the most common complaints of people who develop hypothyroidism, and a number of studies have shown clear linkages between weight gain and hypothyroidism. One study even found that slight fluctuations in TSH can affect weight.
The Guidelines also reinforce the myth and stigma that people who are overweight are "drug-seeking," and looking for thyroid drugs as a weight loss treatment, when they state: "Thyroid hormones should not be used to treat obesity in euthyroid patients." Responsible physicians do not prescribe thyroid drugs to treat obesity. But they do recognize the impact of optimal thyroid treatment on the metabolisms of people with hypothyroidism.
The Guidelines state that "Iodine supplementation, including kelp or other iodine-containing functional foods, should not be used in the management of hypothyroidism in iodine-sufficient areas." This completely overlooks the fact that a growing number of people in iodine-sufficient areas are themselves iodine-deficient. More people are choosing to avoid iodized salt and processed foods that contain iodine, and iodine deficiency is on the rise in the United States. (Find out more about the iodine controversy.)
The Guidelines also suggest that "Selenium should not be used to prevent or treat hypothyroidism." This is despite the fact that a number of studies have shown that selenium can substantially lower thyroid antibodies, and has been shown to have a preventive effect on postpartum thyroiditis. At moderate levels, selenium is considered a safe supplement. What is the motivation of the task force to recommend that patients avoid a supplement that could potentially help moderate the autoimmune reaction and reduce inflammation?
Thyroid Guidelines Related to Fertility, Pregnancy, and Miscarriage
It's also worth noting that the Guidelines recommend that in pregnancy, "the upper limit of the normal range should be based on trimester-specific ranges for that laboratory. If trimester-specific reference ranges for TSH are not available in the laboratory, the following are the recommended upper limits: first trimester, 2.5 mIU/L; second trimester, 3.0 mIU/L; third trimester, 3.5 mIU/L." The Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and Postpartum published in 2011, however, recommend that the upper limits be 2.5 mIU/L in the first trimester, 3.0 in the second trimester, and 3.0 mIU/L in the third trimester, which is .5 less than the new Guidelines. The operative question is: which level should pregnant women follow in their third trimester in order to achieve the best outcome for mother and baby, and why do these two task forces have different recommends for the third trimester?
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Considering that the task force spent more than a year working on these new Guidelines, they seemingly offer very little new guidance. They also fail to reflect the very real changes going on across the United States and in other countries, as practitioners seek to not just simply offer thyroid hormone replacement to achieve a normal-range TSH, but rather, to optimize hypothyroidism treatment to help patients resolve lingering symptoms, and safely improve quality of life and overall health. Sadly, the tyranny of the TSH continues to reign, while the welfare and quality of thyroid patients takes a back seat.
Clinical Practice Guidelines for Hypothyroidism in Adults: Co-sponsored by the American Association of Clinical Endocrinologists and the American Thyroid Association Online