http://thyroid.about.com/cs/testsforthyroid/a/labs2003.htm
Until 2002, the standard was that the normal range for TSH at most laboratories has fallen in the 0.5 to 5.0 range,
with hyperthyroidism being below .5, and hypothyroidism above 5.0.
The guidelines, however, recommend that the range for acceptable thyroid function, and thyroid treatment, shift to
a TSH of 0.3 to 3.0, which is a far narrower range.
Since your doctor is likely to say «I haven«t heard anything about these new changes,» or «the lab is still showing
.5 to 5 as the normal range, and I»m not changing anything until the lab does,» you will want to send some
materials to your doctor ahead of your next appointment. These include the following:
1. January 2003 Press Release from the American Association of Clinical Endocrinologists
Get a copy now
Highlight the third paragraph for your doctor. this paragraph reads: «Until November 2002, doctors had relied on a
normal TSH level ranging from 0.5 to 5.0 to diagnose and treat patients with a thyroid disorder who tested outside
the boundaries of that range5 . Now AACE encourages doctors to consider treatment for patients who test outside the
boundaries of a narrower margin based on a target TSH level of 0.3 to 3.0. AACE believes the new range will result
in proper diagnosis for millions of Americans who suffer from a mild thyroid disorder, but have gone untreated
until now.»
«In the future, it is likely that the upper limit of the serum TSH euthyroid reference range will be reduced to 2.5
mIU/L because >95% of rigorously screened normal euthyroid volunteers have serum TSH values between 0.4 and 2.5
mIU/L.»
http://thyroid.about.com/od/gettestedanddiagnosed/a/tshtestwars.htm
Changing the Reference Range
After noticing that patients who had TSH levels in the higher end of the normal range tended to go on to develop
hypothyroidism more often than those in the lower end of the spectrum, researchers delved more fully into
understanding the validity of the reference ranges in use.
In a statement from the AACE, Hossein Gharib, MD, FACE, and president of AACE at the time, said, «The prevalence of
undiagnosed thyroid disease in the United States is shockingly high...The new TSH range from the AACE guidelines
gives physicians the information they need to diagnose mild thyroid disease before it can lead to more serious
effects on a patient«s health - such as elevated cholesterol, heart disease, osteoporosis, infertility, and
depression.»
Это очень важно!
More recently, researchers have looked at an important question: If the normal TSH range were narrowed, as has been
recommended by AACE and the National Academy of Clinical Biochemistry, what are the implications? One 2005 study
found that using a TSH upper normal range of 5.0, approximately 5% of the population is hypothyroid. However, if
the upper portion of the normal range was lowered to 3.0, approximately 20% of the population would be hypothyroid!
According to another study, an additional 12.8 to 16 million people would be diagnosed with hypothyroidism if the
TSH upper limit was 3.0, and an additional 5.4% to 6.3% of the population --- 10.8 to 12.6 million -- would be
diagnosed as hypothyroid if the upper range for TSH was 2.5.
Clearly, these narrower ranges have huge implications for millions of people who are not being diagnosed or
treated, because their test results are being evaluated according to the old reference range.
There are also many doctors, general practitioners and even endocrinologists who are still routinely diagnosing and
treating patients according to the old reference range simply because they aren»t even aware of the new reference
range guidelines.
А это касаемо ситуации
Interestingly, some patients who have asked for physicians to diagnose and treat them by the new reference range
have been turned down, told off, or even fired by their physicians. This has led to even greater controversy in the
medical community, as doctors are taking sides in the debate over the old and new reference ranges.
О планировании беременности
There is also evidence in the literature that levels above 2.0 during pregnancy can potentially complicate
pregnancy, and that upper level normal TSH levels can inhibit fertility. For example, in early 2005, Drs. Casey and
colleague wrote in the journal Obstetrics and Gynecology that «Pregnancies in women with subclinical hypothyroidism
were 3 times more likely to be complicated by placental abruption.»
Существует связь между ТТГ в пределах нормы и индексом массы тела
There is also a Norwegian study just published in the International Journal of Obesity that found that there is a
positive association between serum TSH within the normal range and body mass index, and the higher the TSH level,
the higher the body mass index and likelihood of overweight or obesity.
These are just a few of the many examples of peer-reviewed literature in respected medical journals that discredit
the argument that treatment is not recommended or warranted for subclinical hypothyroidism. The authors also state
«The only documented adverse health outcome for individuals with TSH levels between 3.0 and 5.0 is progression to
overt hypothyroidism. Levothyroxine treatment would clearly prevent that outcome, but at what price?»
Питание и физические упражнения
Prevention of disease is a major focus of much of today«s medicine, with exercise, diet and medications to prevent
heart disease, obesity, stroke, and many other conditions.
Wartofsky and Dickey: The New Range is More Accurate
Drs. Wartofsky and Dickey defend the shift to the new range, with some caveats. They say: «We will probably never
have an absolutely cutoff value for TSH distinguishing normal from abnormal, but recognition that the mean of
normal TSH values is only between 1.18 and 1.4 mU/liter and that more than 95% of the normal population will have a
TSH level less than 2.5 mU/liter clearly imply that anyone with a higher value should be carefully assessed for
early thyroid failure.»
* In an iodine-sufficient population, the mean TSH is 1.5
* In African-Americans with low incidence of Hashimoto»s thyroiditis, the mean TSH is 1.18, which suggests that
«this is close to the true normal mean for a normal population»
* When people with positive antithyroid antibodies or family history of autoimmune thyroid disease are excluded
from the «reference range» cohort, the normal reference range becomes .4 to 2.5
Касаемо врачей
If your TSH test levels come in below 0.5, or above 2.5-3.0, and your doctor is saying these levels are normal,
make him or her aware of the AACE and American Association for Clinical Chemistry Laboratory Medicine Practice
Guidelines and their 0.3 to 3.0 new reference range. Ask the doctor if he or she will consider a different
diagnosis and treatment based on this new information.
If your doctor refuses to consider your results according to the new range, you may want to look for a new doctor
who is more accepting of change and new evidence, and who will in fact be practicing according to the American
Association of Clinical Endocrinologists new guidelines.
http://thyroid.about.com/od/gettestedanddiagnosed/a/normaltshlevel.htm
As of February 2010, at most laboratories in the U.S., the official «normal» reference range for the Thyroid
Stimulating Hormone (TSH) blood test runs from approximately .5 to 4.5/5.0.
Reference range is a critical component, and the validity of the entire TSH test as diagnostic tool depends on it.
TSH reference range is what determines -- for the vast majority of physicians, who rely on blood tests almost
exclusively -- whether or not thyroid disease is even diagnosed at all, much less treated, and when diagnosed, how
it is treated.
A reference range is obtained by taking a large group of people in the population, measuring their TSH levels, and
calculating a mean value. Supposedly, these people should be free of thyroid disease. What experts are now coming
to understand, however, is that the upper TSH normal range has included people who actually have mild thyroid
disease, and their higher TSH levels skewed the standard curve.
This understanding led to the recommendation in January 2003, by the American Association of Clinical
Endocrinologists, that doctors «consider treatment for patients who test outside the boundaries of a narrower
margin based on a target TSH level of 0.3 to 3.0.»
Implications for Patients
It«s now seven years since the experts have established that this new, narrower TSH normal range of 0.3 to 3.0 is a
more accurate one, and recommended that it become the standard of practice. Yet, the dithering continues. Some
doctors use the new range for diagnosis and therapeutic management -- others refuse to consider anything unless
it»s marked «High» or «Low» on laboratory reports.
Patients can arm themselves with copies of the AACE and National Academy of Clinical Biochemistry reports, educate
their practitioners, and patronize those doctors who stay up on the research, and leave behind those doctors who
stick their heads in the sand and refuse to recognize millions of undiagnosed, undertreated people with
hypothyroidism. |
