Page 31 - Summer2009

often, when there is no known pathology in the pituitary or hypothalamus, measured, whenever thyroid function is tested,
DQG QR GH¿QLWH FKURQLF GLVHDVH GLDJQRVLV LW LV DVVXPHG WKDW RQO\ SULPDU\ it will be found that a low T3 level is a common
hypothyroidism needs to be screened (and often only with a TSH test, the condition, leading to a lot of illness and death,
most likely test to be abnormal if only primary hypothyroidism is pres- while the patient is told that their thyroid func-
ent). tion is normal (just because the TSH level, and
The conventional approach to screening for, diagnosing, and treat- SHUKDSV D 7 OHYHO LV QRUPDO 9,10,11,12
ing hypothyroidism is to measure the TSH level only, or occasionally the
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UDQJH ´ 7KH XVXDO WUHDWPHQW LV 7 RQO\ ZKLFK SK\VLFLDQV DVVXPH ZLOO TREATING THYROID UNDERACTIVITY
DOZD\V FRQYHUW VXI¿FLHQWO\ LQWR WKH DFWLYH KRUPRQH 7 ,Q FRQYHQWLRQDO OPTIMALLY
treatment the T3 level is rarely if ever be measured, especially using new, The two commonly known negative effects
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their treatment of hypothyroidism! roid hormone are cardiac arrhythmias (dangerous
The only way to be sure that no form of hypothyroidism is present, irregular or rapid heartbeats) and osteoporosis
when the patient exhibits suspicious symptoms of hypothyroidism, is to (thinning and fragility of the bones). However,
always measure the free-T3 serum level (preferably by the new, more ac- most such thyroid-induced incidents occurred
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When a low free-T3 level is not suspected or measured for, it will not be push for supra-physiologic (above-normal) blood
found, reinforcing the perception that low T3 levels, without abnormal OHYHOV RI 7 LQ RUGHU WR REWDLQ RSWLPDO WK\URLG
7 DQG 76+ OHYHOV DUH UDUH RU LQVLJQL¿FDQW ,I WKH )7 OHYHO LV DOZD\V function. It was only when a more sensitive TSH

SOME REASONS WHY T3 IS NOT MEASURED AND PRESCRIBED MUCH MORE OFTEN

Much of the reason has to do with the physiology of the T3 hormone versus the T4 hormone. Whereas T4 is long-acting, with
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a half-life of a week, T3 is short-acting, with a half-life of 8-12 hours, depending on whether it is taken on an empty stomach or after
meals. So T4 produces a more stable and consistent blood level; a blood test showing a certain T4 level can be relied upon to stay
relatively stable, no matter when it is measured. However, I have found, over a 20-year time-period, in over 5,000 patients, that the
free-T3 level does not fluctuate as much as is commonly believed. Also, it is important to understand the dynamics of
testing in relation to the previous couple of doses of T3-containing thyroid hormone preparation.
If one or two doses of T4 are missed, the blood level will not be much different than if those doses had been taken.
But if one, and even more so, if two doses of a T3-containing preparation are missed in the 24 hours prior to the blood
draw, the blood level could be extremely low, indicating the patient needs a lot more T3 when in fact the level may have
been normal, even optimal, while they were taking the prescribed doses regularly. It is lack of knowledge and sensitivity to
the wide fluctuations in the serum level of T3, depending on the timing of doses and blood draws, that has led to the fear
that endocrinologists have for using T3 and/ or T4/T3 combination preparations. One T4/T3 combo, Euthroid, an excellent
product in my opinion, was even taken off the market by the FDA some years ago because physicians did not know how
to take into account the time at which their measurements of the T3 hormone should be done in relation to the last 2
doses, in patients taking this product.
Secondly, the T3 level is affected by non-thyroidal factors such as stress, other diseases, several metal/mineral levels
(such as lithium, mercury, copper and aluminum), the patient’s degree of arousal and activity, etc. It is wrong to assume
that if T3 is low only because of another disease or non-thyroidal factor, then it is not the concern of the endocrinologist
but of the specialist covering the other disease or factor! And rarely is it ever communicated to the other specialist that
“their disease or factor” is lowering the patient’s thyroid function, or what might be done to remedy the low T3 level.
Endocrinologists and internists need to accept responsibility for their patient’s thyroid function as measured in the FT3
level, and not just the apparent normality or abnormality of the thyroid, pituitary and hypothalamus glands.
Lastly, for many years, available blood tests for the T3 hormone were not as accurate as those for T4 or TSH level. In
the past 10-15 years, the tracer-dialysis method for measuring T3 has been available, although it costs 8-10 times as much
as the non-dialysis test. Because it is so crucial to ascertain exact thyroid function, there is no excuse for not having this
accurate test performed; it is not at all expensive when compared to many other tests that are run much more commonly,
such as MRIs and CAT Scans. It only costs about $80 and is covered by health insurance. Instead of getting this crucial
information, many physicians still have these concepts of unreliability and expense in their heads and they are foregoing
the accurate measurement of the crucial T3 level, which depicts the actual level of thyroid function.

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