TSH References

For an introduction to TSH, or thyroid stimulating hormone, see TSH Levels. Links to the TSH References pages are in the column at the right on this and every page in this section.

See also T3 References and Desiccated Thyroid References.

Highlights

• Hypothyroidism and the TSH Range: See The American Association of Clinical Endocrinologists' recommendation to consider 3.0 the high end of the TSH range, along with other references indicating that a TSH level above 2 should be questioned.
• Suppressed TSH Levels shows that a below-range TSH level does not necessarily indicate hyperthyroidism. These findings are supported by patients' experiences. See TSH and Patients' Experiences: Suppressed to 0.5.

A little background

Until the mid-1970s, doctors diagnosed hypothyroidism and hyperthyroidism partly by less-than-perfect tests, and largely by signs and symptoms. In around 1975, however, the also-imperfect TSH test was proclaimed as "the gold standard." No studies were done to see if TSH test results correlated with the conditions of a large number of patients, or with actual thyroid hormone levels, yet the TSH test now rules the world of thyroid diagnosis. Clinical diagnoses are typically given little or no weight when the TSH level is within its range.

However, indications of the unreliability of the TSH test keep coming to light in medical studies. The range of TSH levels considered "normal" is getting narrower.

The references in this section are limited to those about problems with and within the typical TSH reference range of around 0.3 to 5.5 mU/L. The fact that a TSH level above the reference range correlates with hypothyroidism is recognized in medical circles and doesn't need further documentation.

The need for these references

Numerous medical journal articles show that the TSH test is not "the gold standard" of euthyroidism and non-euthyroidism that it is purported to be. It often correlates poorly with symptoms and actual thyroid hormone levels, it can't detect central hypothyroidism, and conditions caused by hypothyroidism (such as depression, heart disease, and high cholesterol) may be present with a "normal" TSH level.

General practitioners have a lot of material to cover in medical school. They are taught that the TSH test is "highly sensitive" and is usually the only test needed to diagnose thyroid conditions, but they are not, apparently (according to what they tell patients), told about its multitudinous documented shortcomings. Neither are endocrinologists.

Doctors are also taught that central hypothyroidism is rare — but is it? If doctors rarely look for it, they'll rarely find it, but numerous thyroid patients who have posted in alt.support.thyroid have had low free T4 and free T3 levels coupled with low TSH levels, and have found their TSH levels largely irrelevant to how they feel. (See the "Patients' Experiences" links at the right.) Either far more people have central hypothyroidism than is generally believed, or TSH is a hormone whose sensitivity is not necessarily in response to actual thyroid hormone levels.

It's difficult for doctors to keep up with the latest articles about everything. As thyroid patients in alt.support.thyroid, we have a vested interest in following this subject, so we've compiled references that we consider useful.

Medical articles and factors to consider

For every article that discusses the fallibility of the TSH test or the problems with its reference ranges, there is probably another article praising this test. While reading through the latter category, however, the absence of a critical factor is glaring — the patient's well-being. Articles that instruct doctors to rely on the TSH test typically discuss only numbers. They fail to mention whether or not patients feel well at a TSH level that may be in range but higher than 2 or so, or below the low end of the reference range.

In the "Patients' Experiences" compilations, we read that the ideal TSH level ranges from suppressed for many to close to 2 for others, while some people have hypothyroidism symptoms if their TSH level rises above 1. Occasionally we read about people with a TSH level above the reference range who have no symptoms of hypothyroidism. What applies to one patient doesn't necessarily apply to the next one.

Depression, high cholesterol, hypertension, muscle and joint pain, menstrual irregularities, and constipation are among the symptoms that patients with hypothyroidism may have, regardless of whether or not the TSH test has indicated hypothyroidism. If the cause of these symptoms is not diagnosed correctly, the symptoms are either untreated, or are treated with other medication. Applying a bandaid solution to each symptom is like pumping air into a leaky tire tube without taking the nail out and sealing the tube. Treatment for the root cause — an underfunctioning thyroid — usually eliminates the need for other medications. With depression, antidepressants often fail to work when the underlying cause of hypothyroidism is untreated.

In the US, the Food and Drug Administration (FDA) lists in its mandate for consumer protection "...to see that...medical devices [Americans] use are safe and effective...." A test that very often produces inaccurate results yet is unquestioned is neither safe nor effective. As Nikki Tovell wrote in a letter to the British Medical Journal in June 2000: "..if a patient has signs and symptoms of illness and test results are negative, you aren't performing the right tests."

The TSH test is a useful test for some thyroid patients. The problem is that this test often produces a "normal" result when the patient presents with numerous symptoms of hypothyroidism. Symptoms, family history, and associated illnesses need to be considered with lab results, especially when the particular lab test used has a hit-and-miss record.

When medical articles and doctors present different points of view, which one do we support? In our opinion, the patient's well-being should be the tie breaker. Fortunately, the research supports our experiences.

Lois Summers
with Kevin G. Rhoads, PhD