At the time of the announcement, almost three years ago, AACE estimated that the new guidelines would double the number of people who have abnormal thyroid function, bringing the total to as many as 27 million, up from 13 million thought to have the condition under the old guidelines. These new estimates would make thyroid disease the most common endocrine disorder in North America, far outpacing diabetes.
The announcement from AACE was seen by many as a long-overdue and much-needed improvement in the level of awareness of endocrinologists. After decades of denying that patients within the normal range of TSH could in fact have a thyroid condition, they were acknowledging what patients and advocates had been saying quite vocally for years: that the high and low end of the TSH normal range were not, in fact, normal for most people.
"...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..."
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.
Untreated thyroid disease can severely compromise quality of life, and in some cases even be fatal. Untreated thyroid disease can cause or contribute to numerous debilitating symptoms and conditions, including, among others:
- weight problems and obesity
- exhaustion and fatigue
- depression and anxiety disorders
- heart disease
- birth defects
Interestingly, however, in the past three years, most laboratories in the U.S., despite what are clear communications from both AACE and the Laboratory Medicine Practice Guidelines, have not revised their TSH reference range, and remain with the 0.5 to 5.0 range as their "normal range."
Some practitioners have adopted the new range for diagnostic and treatment purposes. Some physicians, who are aware of the new guidelines, have, however, chosen not to follow them, and remain with the older reference range. Some of them have made this decision because they do not agree with the new range, medically. Others are attempting to "play it safe" and protect themselves because the laboratories have not yet gone with the change, and these doctors are reluctant to diagnose a thyroid condition unless the printed lab report flags a TSH test result as "high" or "low."
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.
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.
The Debate Goes Public
In September of 2005, two articles appeared in the Journal of Clinical Endocrinology and Metabolism, presenting the two sides of the argument.
Martin Surks, Gayotri Goswami and Gilbert Daniels argued that the reference range should remain the same in their article "Controversy in Clinical Endocrinology: The Thyrotropin Reference Range Should Remain Unchanged," while Leonard Wartofsky and Richard Dickey argued that "The Evidence for a Narrower Thyrotropin Reference Range is Compelling."
Surks, Goswami and Daniels base their argument on their assertion that "because routine levothyroxine treatment is not recommended for subclinical hypothyroidism, it is certainly not warranted in individuals with upper reference range TSH [TSH 2.5 to 4.5]."