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Dr. John Lowe critique of the four studies

Updated: Mar 30, 2023

Written by Dr. John Lowe, MA, DC and The Thyroid Patient Advocacy UK


Dr. John C. Lowe, a long-time researcher into hypothyroidism, hypometabolism, fibromyalgia, and the use of T3 drugs for thyroid and metabolic conditions, has published a groundbreaking, must-read analysis. He has looked at the four studies published recently in major medical journals, all of which were blanketly critical of the use of T3. Dr. Lowe has deconstructed the research, and pointed out the numerous major flaws — flaws that will force your physician to rethink the validity of the earlier findings. For any thyroid patient who doesn’t feel well on T4 (levothyroxine, i.e., Synthroid) alone, I urge you to print off the PDF version of the analysis report, and bring it to your physician. And if you have a doctor or endocrinologist who has dismissed T3 because of the recent research, then even more reason to make sure you share a copy of Dr. Lowe’s paper, Thyroid Hormone Replacement Therapies: Ineffective and Harmful for Many Hypothyroid Patients. You can also read an html version online.

Now, a special message from Dr. Lowe:

Some six months ago, medical journals published four studies by endocrinologists that piqued attention in the alternative medicine community. In the studies, the endocrinologists compared the effectiveness of T4-replacement with that of combined T4/T3-replacement. “Replacement,” of course, refers to doses of thyroid hormone that keep the TSH level within its current lab reference range. Keeping this definition in mind is crucial to understanding what the four studies actually showed, and what they didn’t show.

What the studies showed is this: Neither form of replacement therapy relieved hypothyroid patients’ symptoms or abnormal test results. In fact, the four studies are proof positive that replacement therapies leave many hypothyroid patients suffering. Most of the researchers accurately reported this negative treatment finding. However, the finding is buried deeply within their full-text published reports; to see that it’s there, one must first get a copy of the journal articles — which most doctors and patients won’t do — and then read carefully.

In contrast to what they did find, the endocrinologists clearly broadcast something they did not find: that no approach to T4/T3 therapy is more effective than T4 alone. As I explain in detail in my critique, the difference between what they did find and what they didn’t find is no minor distinction; it can seriously impact the clinical care of hypothyroid patients.

The false reports of the endocrinologists are almost certain to implant a false belief in the minds of doctors. As a result, the doctors are likely to restrict millions of hypothyroid patients to T4-replacement despite the studies showing that it’s ineffective for many patients.

The four studies appeared to be a response by the endocrinology specialty and its corporate sponsors to a study published in 1999 in the New England Journal of Medicine.[1] In that study, researchers reported a finding that threatened the market for T4-replacement therapy. The finding was that adding T3 to hypothyroid patients’ daily T4 dose improved their cognitive function. As a result of that study, many hypothyroid patients began asking their doctors to add T3 to the T4 they were already taking. The result of the four 2003 studies –that combined T4/T3-replacement was no more effective than T4-replacement — contradicts the result of the 1999 study.

A few alternative thyroid doctors criticized some of the 2003 studies. The main place their criticisms were published was — the website of thyroid patient advocate Mary Shomon, where the democratic spirit is exercised by publication of dissenting views.

However, no criticism of the studies was published in any major medical journal.

This was certainly no surprise to us at the Fibromyalgia Research Foundation. Our research team learned long ago that the pages of major medical journals are almost always closed to thyroid researchers except under one condition: when they’re reporting study results that support the prejudice of the endocrinology specialty in favor of T4-replacement.

If a research team’s study finding isn’t favorable to T4-replacement, the team might as well forget submitting the report to any major medical journal — it’s extremely unlikely that it would be accepted for publication. A truly rare exception was the 1999 study reporting that T4/T3 replacement was more effective than T4 replacement. I’m still wondering how that report slipped past the endocrinology specialty’s censors.

The main editorials on the four 2003 studies in major medical journals were written by endocrinologists. In each of the editorials, the endocrinologists echoed the false reports of the endocrinologists who conducted the studies.

We’ve published my critique of the four studies at The critique is a formal logical analysis with ethical implications. The purpose of the critique is three-fold: (1) to explain the fallacy in the endocrinology researchers’ reports; (2) to give evidence that for many patients, T4-replacement is both ineffective and harmful; and (3) to question the endocrinologists’ motive in advising that T4-replacement remain the treatment of choice, despite the studies showing it to be ineffective in relieving many patients’ symptoms.

I am sending notice of the critique to these endocrinology researchers and the endocrinologists who wrote editorials repeating the false conclusion. We’ll let our readers know the content of any replies I receive from them.

I want to thank my Editor, Jackie Yellin, for working long and hard with me to make the critique clear and logically precise. Also, I want to thank Michael Yellin for his fastidious proof-reading.

I also thank Mary Shomon for notifying her readers about the critique. She tells me that she’ll advise patients who are restricted to T4-replacement and still suffering from hypothyroid symptoms to print the critique as a pdf file and take it to their prescribing doctors.

Doctors who read it will know why their patients continue to suffer from hypothyroid symptoms despite using T4-replacement. The doctors will also be aware that restricting their patients to T4-replacement may increase their drug use and put them at risk for several diseases that can lead to their premature death.


[1] Bunevicius, R., Kazanavicius, G., Zalinkevicius, R., and Prange, A.J. Jr.: Effects of thyroxine as compared with thyroxine plus triiodothyronine in patients with hypothyroidism. N. Engl. J. Med., 11;340(6):424-429, 1999.

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