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Letters Related to Dr. Lowe's Rebuttal to

British Thyroid Association |

Subject: Are euthyroid

patients harmed by thyroxine therapy

Date: June 20, 2010

From: Author prefers anonymity

editor@...

June 20, 2010

Question: I

am a general practitioner in the UK. Many of my patients have told me that

they recovered from their hypothyroid symptoms after they found a private

doctor who treated them with thyroxine despite their normal TSH levels.

These patients had been denied thyroxine treatment by doctors within the

National Health Service because of their normal TSH levels. So many

patients have told me this that I have developed reservations about ruling

out hypothyroidism and the need for thyroxine therapy based on a normal TSH

test.

Many

more of my patients with normal TSH levels ask me to prescribe thyroxine or

Armour Thyroid. I am hesitant to comply because of the Royal College of

Physicians' statement about adverse effects from unnecessary thyroid

hormone therapy. May I have your point of view on the potential for adverse

effects from thyroxine treatment when patients do not actually need it?

Dr. Lowe: I'm familiar with the

statement you refer to by the Royal College of Physicians. Specifically it

is: " . . . some patients are inappropriately diagnosed as being

hypothyroid (often outside the NHS) and are started on thyroxine or other

thyroid hormones which will not only cause them possible harm

.. . . " (Italics and bold mine.)

Like

too many other statements or implications by the Royal College of

Physicians, when applied to the general population, this one is patently

false.

Unless

you're a geriatric specialist whose patients are among the most fragile of

human beings, even if they don’t need supplemental thyroid hormone, a

trial of thyroid hormone therapy is harmless. If the hormone doesn’t

help them, you can wean them off it and then have them stop it altogether. No

harm done!

Proof of this is in the history of FDA-guided studies of the potency and

stability of T4. To test T4 for potency and stability, researchers—using

FDA test guidance!—have traditionally used volunteers who

were " euthyroid, " meaning, of course, that they subjects had

normal thyroid function test results. Moreover, FDA test guidance has

allowed researchers to use euthyroid volunteers to test higher-than-physiological

(supraphysiologic) doses of T4.[1,p.109]

I ask the Royal College of Physicians: If it were likely to harm euthyroid

volunteers, why would FDA-test guidance allow researchers to use them for

the testing? And why would institutional review boards approve the studies

as not potentially harmful to the volunteers?

The

answer is simple, of course: A trial of thyroid hormone therapy—even

for people with perfectly normal thyroid function—is harmless,

even when they use supraphysiologic doses.

Only recently have researchers suggested that rather than testing euthyroid

volunteers, they would best use thyroidectomized patients. But the

researchers' reason for this suggestion has nothing whatever

to do with any harm ever done to euthyroid volunteers in the studies. The

testing hasn't harmed the euthyroid volunteers, nor will a trial of thyroid

hormone therapy harm practically any of your euthyroid patients except

possibly the most severely fragile of them. But, then, a cup of coffee is

just as likely to harm those fragile folks.

I just

don't understand something: How does the Royal College of Physicians (as

with this particular issue) and the British Thyroid Association make

scientifically false statements and stand by them in the face of proof that

they are false, yet receive no official reprimands from regulatory

authorities in the UK? To me, their false statements are an affront to the

noble tradition of science, and the organizations sticking by their false

statements in the face of refuting evidence reduces the statements to

examples of pseudoscience.

At any

rate, I hope this reply is helpful to you in providing your patients with

harmless trials of thyroid hormone therapy, whether they truly need it or

not.

Reference

1.

Royal College of Physicians. The

diagnosis and management of primary hypothyroidism. 2008.

2. Eisenberg, M. and DiStefano, III, J.J.: TSH-Based

Protocol, Tablet Instability, and Absorption Effects on L-T4 Bioequivalence.

Thyroid, 19(2):103-110, 2009.

(This Q & A was published simultaneously at drlowe.com)