Understanding Thyroid Lab Tests
By Kenneth N. Woliner, M.D.
Mary
was frustrated. She always had trouble keeping a
normal weight, but after having her second child
two years ago, she couldn’t shake the extra
forty pounds she gained. Mary became so
fatigued that any amount of exercise seemed
impossible. Previously, she would do
Spinning classes three times a week, but now,
she had not made it to the gym in six months.
“I haven’t given up,” she protested.
“They still take their dues out of my checking
account every month.” Mary’s skin got so dry
and oily that her face broke out in acne.
Her moods took a turn south, and that led to
binge eating in front of the TV. When her
primary care doctor wanted to put her on
anti-depressants, Mary found her way to my
office.
After
taking a detailed history and performing a
complete physical exam I said, “I think your
thyroid condition is under-treated.”
“How
could that be? My other doctors said my thyroid
tests were normal!”
“Unfortunately,
they only did one type of test. Despite being
called ‘ultra-sensitive’, the ‘TSH’
blood test has its limitations.1
It isn’t accurate for everyone.”
“Shouldn’t
an endocrinologist know which blood tests to
order?”
“My
mentor, Dr. Richard Shames, author of the book
‘Thyroid Power’, talks about how patients
are tyrannized by this one test, and how the
doctors who rely upon it often withhold
effective medication.2 Perhaps
it was their training that emphasized blood
tests over listening to patients, or it could be
that they make so much money doing lab testing,
that they have come to rely upon labs almost
exclusively. Regardless, this one test,
despite saying you are ‘normal’, doesn’t
prove that you don’t have a real medical
condition that requires further treatment. I
would like to do a more complete workup.”
Mary returned a week later to review her lab
results. “After draining me of all my blood, I
hope you know what to do to make me feel
better.”
“I’m sorry – being a family practitioner,
I look at other things besides thyroid.
Being overweight can be caused by lots of
things, thyroid being only one of them. But I
will say this, your tests definitely say you are
under-medicated.”
“Now you’re going to tell me to increase my
Synthroid by 0.025 or something like that.”
“Actually, no. The word ‘doctor’ means
‘to teach’. I want to spend the next
half-hour teaching you what these tests really
mean. By the end this visit, I think you will
know more about thyroid disease than most
endocrinologists. Later on, when you learn more,
I want you to help choose among options of what
to do next. In my opinion, the days of
paternalism in medicine are long over. I want
you to take an active role in your care.
“Let’s start with that first test, the TSH.
It stands for ‘Thyroid Stimulating Hormone’
– the substance your brain makes to tell the
thyroid to make more thyroid hormone. To
help you understand how this works – I want to
make a metaphor to a cold apartment in
Minnesota
. If it is really cold, the thermostat
(your brain) will send lots of electricity (TSH)
to the boiler (your thyroid gland) to make lots
of heat (thyroid hormone). As the
apartment heats up, the thermostat will still
send some electricity, but maybe not as much, to
still make heat, but only enough to keep the
apartment at the right temperature. If
there is a raging fire in the apartment (or a
space heater right next to the thermostat), the
thermostat won’t send any electricity to the
boiler and no heat will be produced.”
“So where’s my TSH at? I’m sooooooo
cold right now. Can I borrow your lab coat?”
I handed my coat to Mary. “Here you go. Your
TSH is at 0.02 with normal being from 0.5 to
5.5.”
“Wait! By this test – I should be
taking less medication, not more. I
already feel cold. Please don’t decrease
my dose. It’s hard enough getting out of bed
already.”
“Don’t worry – I’m not decreasing your
dose. I said you were under-medicated and I
meant it. This test doesn’t say you’re
getting too much medication. On the contrary, it
proves that you are NOT getting too much.”
“But I’m outside the normal range. The other
doctors always decreased my dose when that
happened. And I always felt worse when
they did. Promise you won’t take away my
medication?”
“I understand your fear, but stop for a second
and remember the metaphor. When there is too
much heat in the apartment, such as the danger
of a fire, NO electricity goes to the boiler. I
do not think you have a raging fire inside you.
The mere fact that your TSH is detectable
signifies that you don’t have too much thyroid
hormone in your body. I know you’re not
overmedicated because you are still making TSH.
Your body is asking for more heat.”
“But why am I outside the normal range?”
“Every test has the potential for error, and
we call them type 1 and type 2 errors. Type 1
error is when we think that there is something
there when it really isn’t. It happens when a
test is very sensitive (it picks up most
disease), but is not specific (it tests positive
when no disease is present). Type 2 error is
when the test is very specific (it doesn’t
label you with a disease if you don’t have
one), but not sensitive enough (it misses you,
even if you do have a medical condition).3
To prevent too many ‘false positives’, too
many people from being called ‘Hypothyroid’
when they are indeed normal, the lab makes a
cutoff at some point. Unfortunately, their
cutoff point cuts off many patients from getting
proper treatment. We call them ‘false
negatives’.”
“I would think in a disease like HIV, you
really would want to make sure someone had it
before you labeled them, but low thyroid
doesn’t have that stigma. I don’t understand
why they do things this way.”
“Perhaps another time we’ll talk about the
science or politics of medicine, but for right
now I want to assure you, you are not getting
too much medication.”
“Okay, let’s move on. But you said I
definitely was under-medicated. How do you
know?”
“There are actually three sets of tests that
are even more important than the TSH.
Let’s go through them. The first set describes
the levels of free hormones in your blood
stream. I test for ‘Free T4’ and ‘Free
T3’. ‘T4’ describes a thyroid molecule
with four iodine atoms attached to it.
‘T3’ is the same thing, but with one of them
lopped off. It actually is four times as
potent as T4, so I test for both. I no
longer test for Total T4, Total T3, Free
Thyroxine Index (FTI), and T3 Resin Uptake
(T3RU). They can be thrown off by toxic
chemicals and drugs (lead poisoning, birth
control pills, hormone replacement therapy,
seizure medication, blood pressure and
cholesterol drugs (Propranolol, Gemfibrozil),
and high dose aspirin (used for arthritis));
deficiencies of vitamins and minerals (Vitamin
E, Selenium, others…), and chronic disease
(liver and kidney disease, Parkinson’s
Dementia).4 he only reason to
continue to draw those tests is to bill you or
your insurance company. They don’t change
prognosis or medical management one iota.”
“You seem a little jaded.”
“I’m sorry – I sometimes get a little
carried away. I just get upset when doctors do
tests that do little to help their patients,
just to line their pockets. And even if a
‘nameless, faceless’ insurance company is
paying for that testing, it comes back to the
patient eventually. The insurance company raises
the premiums the employers pay. The employers
pass on these premium increases to their
employees, or worse yet, drop coverage
altogether. I have quite a few patients in that
situation. It just isn’t right.”
“No. It isn’t.”
“Back on subject – the Free T4 and Free T3.
For this lab, the normal for Free T4 is 0.8 to
1.8. You’re only at 1.2. For Free T3 –
normal is 230 to 420. You are even lower here
– coming in at 240. To make sense of
this, in the marathon of life – you might
still be in the race – but instead of
finishing first, second, or third – you’re
an also-ran.”
“It seems my other doctors want to wait until
I’m out of the race with a broken ankle before
doing anything to help me. What other tests do
you got there?”
“Other tests are used to determine
hyperthyroidism and thyroid hormone resistance.
I actually didn’t waste your money drawing a
Thyroglobulin. It is elevated for a
variety of reasons, and really is only useful to
follow patients after have been treated for
differentiated thyroid cancer.5 It
isn’t useful for predicting thyroid cancer.
There are other modalities used for that.
If you would like – come to the local hospital
where my next lecture will be: ‘Thyroid Cancer
– Holistic approaches to diagnosis and
treatment.'6 I didn’t do a test for
‘TSH Receptor Antibodies’ or the ‘TSH
following TRH (Thyroid Releasing Hormone) as you
do not have symptoms or signs of
hyperthyroidism. I also didn’t do a
‘Reverse T3’. Some people, especially
when they are deficient of vitamins and
minerals, or exposed to toxic amounts of cadmium
or mercury, have trouble converting T4 to T3.
Instead, they make ‘Reverse T3’, a form that
doesn’t work. Unfortunately, most doctors are
totally unaware of the Reverse T3 phenomenon,
and even worse, most labs do not properly assay
for it.7 Your HMO insurance doesn’t
pay for labs to be sent to any of the few
reference labs around the country that actually
perform a reliable assay, so I didn’t bother
drawing the test. With the common laboratories
around here, it always comes out normal, even
when there is a real problem.
“The next two tests you’ll find very
interesting. They are called ‘Thyroid
Antibodies’, and come in two forms,
‘Anti-Microsomal (Thyroid Peroxidase)
Antibodies’ and ‘Anti-Thryoglobulin
Antibodies’. These often elevate postpartum.8
I notice your symptoms got worse after having
your second child.”
“Yes, I haven’t been able to do anything at
all. What were my numbers?”
“They were off the chart. Normally, they
should be undetectable, but yours were 1,532 and
939 respectively. You have Hashimoto’s
Thyroiditis. You may have even had these
antibodies all your life. here is no way
to know. The other doctors never tested you for
them.”
“I’m mad, that’s true. But right now I
just want to get better. What do I need to
do now? And when will I need to come back to be
retested?”
“Interestingly enough, you will never need
another thyroid blood test again.”
“Back up a minute… Didn’t you say I had
Hashimoto’s Thyroiditis? Don’t you
need to follow my blood counts every three
months like the other doctors have been
doing?”
“These blood tests – they don’t work for
you. They didn’t help you over the last 15
years you’ve been having problems, even when
your problems became worse over the last two. It
is because these thyroid antibodies variably
bind up the hormones you have. There is no way
to tell how much thyroid hormone you need based
upon blood tests.”
Mary’s eyes were rolling back into her head
and her mouth was sagging open. She obviously
needed more of an explanation. “Let’s try
another analogy. When a traffic helicopter
flies overhead, it sees all the cars on the road
– and says, ‘There’s plenty of
transportation to take people around the
city.’ But what if a meter maid noticed
they didn’t pay their parking tickets and put
a red parking boot on some of them. They
wouldn’t be able to go anywhere. In
order to have enough transportation for the city
– you might need twice as many cars.
Unfortunately – there is no way to know how
vicious that meter maid is – we just know that
she is there. There is no way to know how much
of a negative effect those thyroid antibodies
are having, we just know that they are there.
The presence of thyroid antibodies throws off
every thyroid test, including the TSH.”
Mary was exasperated. Slumping back in her
chair, “Then how will I ever know how much
medicine to be on?”
“You forgot, there is one more type of testing
that will be most effective for you.” Mary
became interested again and leaned forward.
“We should test the effect that thyroid
hormones have on your body. With hormone
resistance, it is often easier and more
effective to test the function of the hormone,
not the actual level. This idea isn’t new.
In Type II Diabetes, we know there is insulin
hormone resistance. We don’t check insulin
levels – we check what it does by monitoring
your blood sugar levels. There are many
different types of thyroid hormone resistance.
In addition to the Reverse T3 phenomenon and
Thyroid Antibodies, some people are deficient of
essential fatty acids or other vitamins,
limiting thyroid hormone’s ability to get into
the brain or other cells to have its full
effect.9,10 We just have to check
what thyroid hormone does in your body.
“Though active thyroid hormone is needed to
lower cholesterol and blood pressure, to raise
blood sugar when hypoglycemic, and to convert
beta-carotene into Vitamin A, there is no
specific blood test to show whether thyroid
hormone is working properly or not. Dr. Broda
Barnes, MD, PhD, who wrote one of the first
books on hypothyroidism, ‘Hypothyroidism: the
unsuspected illness’, described a simple
temperature test using a mercury thermometer.11
Mercury thermometers are more accurate than
digital ones, and because they are hard to find
nowadays, I’ll sell one to you for a dollar
(that’s all they cost me). Here is a handout
to describe how to do the test.
“Lastly, I want you to take this sheet of
paper that has ten, 10-point scales on it. I
want you to write down the ten things most
important to you. For the first line, fill in
‘Energy Level’. Zero will be where you
can’t get out of bed, ten being where you are
excited about travel and are planning a fun
trip. If you are spending money you don’t
have, you might be at a twelve. Please call me
before they take away your credit cards.” Mary
smiled. “Fill in the other nine items with the
things most important to you: weight,
skin, and mood are three things you’ve already
mentioned. Many people also put down
constipation, hair growth/loss, nail quality,
and cold/heat intolerance, menstrual periods,
and libido. Lastly, there are checkboxes at the
bottom for ‘Palpitations’ (sensations of
your heartbeat) and ‘Anxiety’. If you
feel like you have too much coffee or caffeine
in your system, you might be getting too much
medication. Every so often, scale yourself. If
you are getting better – then we know you are
on the right track.”
“I think I finally understand these tests, so
what do we do now? You said I would have options
in choosing my own care.”
“You do. Because you are lower in T3 than T4,
and because many of my patients report they feel
better when they add some T3 to their regimen, I
think whatever you choose should include that.12
Some people will take two pills, perhaps the
Synthroid (a pill that contains synthetic T4
only) you are on now, plus another pill called
Cytomel (a pill that contains only synthetic
T3). Other people that were never really happy
on T4 alone find it easier to switch completely
to a combination product that has both T4 and T3
in it (Armour Thyroid, Nature Thyroid,
others…). Armour Thyroid, which has been
around for over 100 years, is standardized by
the USP (and is more stable than Synthroid), and
has the advantage of costing only $0.12 / pill
wholesale. Many people that do not have
insurance prefer it for price reasons alone.
What do you think you want to do?”
“I didn’t much like that Synthroid, and
since my health insurance doesn’t pay for
medications, that Armour Thyroid sounds like a
good idea. But what dose to we start at?
How often do I need to come to see you?”
“The equivalent dose to what you are on is
only 30 mg (or if using old apothecary units -
one half grain). Let’s start with that, but
I’ll give you lots of pills. After two weeks,
if your scales are not close enough to ten, and
you haven’t had any side effects such as
palpitations or anxiety, increase by one pill a
day. You can do this each two weeks up to four
pills a day (120 mg) without causing any long
term side effects. Please go slowly.
Dosing thyroid is almost like running on ice. It
takes a while to get the full effect of the
medicine, but if you increase too quickly –
you hit the wall (palpitations).”
“But what about osteoporosis? Every time
I begged my endocrinologist to give me more
medication, he said my bones would become thin
and break. I don’t want that to happen.
I’m short enough as it is!”
“I said we wouldn’t have to do any more
blood tests for thyroid, but you will have to be
monitored. Fortunately, doses less than
120 mg (2 grains) per day of Armour Thyroid
(equivalent doses would be 200 mcg/day Synthroid/Levoxyl
(T4) or 50 mcg/day Cytomel (T3)) have been
studied long term and do not cause any long-term
side effects, not even osteoporosis. In
fact, those taking thyroid had thicker bones
than those patients not on medication! 13
Doses greater than that have not been studied,
so to be safe, we will need to do annual bone
density screening if we go higher than 120
mg/day. Lastly, Hashimoto’s Thyroiditis can
cause osteoporosis in of itself. We should do a
baseline test now.
“I plan on seeing you in two months – that
will give you enough time to see if you need 120
mg or less. I hope that you will eventually
learn how to manage your condition on your own
and we can space out these visits. When you are
in control, you probably won’t have to see me
for thyroid but once a year.”
Mary’s bone density was well within normal
limits. Her energy, weight, skin and mood all
normalized on a dose of 90 mg of Armour Thyroid
per day, costing her only $7.11 / month from the
local pharmacy.14 As she didn’t
need any more thyroid blood tests, nor excessive
visits each month with a doctor – she saved
some money to buy Christmas gifts for my office,
as well as for her husband and two children.
REFERENCES:
1Lueprasitsakul W, et al. Flavonoid
administration immediately displaces thyroxine
(T4) from serum transthyretin, increases serum
free T4 and decreases serum thyrotropin in the
rat. Endocrinology 1990; 126:2890. 2Shames
RL and Shames KH. Thyroid Power: ten
steps to total health. Harper Resource;
ISBN: 0060082224; 2002. 3Kirch W.
Misdiagnosis at a university hospital in four
medical areas. Medicine (
Baltimore
) 1996;75(1): 29-40. 4Becker DV, et al.
Optimal use of blood tests for assessment of
thyroid function. JAMA. 1993;
269:2736-7. 5Franklyn JA, et al.
Free triiodothyronine and free thyroxine in sera
of pregnant women and subjects with congenitally
increased or decreased thyroxine binding
globulin. Clin Chem 1983; 29(8):1527-30.
6Woliner, KN. Thyroid Cancer – Holistic
approaches to diagnosis and treatment.
7Wilson JD, et al. Editor. Williams
textbook of endocrinology, 9th ed. W.B Saunders
Company 1998. ISBN 0-7216-6152-1.
pps 297-404. 8Stagnaro-Green A.
Recognizing, understanding, and treating
postpartum thyroiditis. Endocrinol Metab
Clin North Am 2000: 29(2):417-30. 9Maenpaa
J, Liewendah K. Peripheral insensitivity
to to thyroid hormones in a euthyroid girl with
goiter. Arch Dis Child. 1980; 55:207.
10Brent
Ga.
The molecular basis of thyroid hormone
action. N Engl J Med 1994; 331:847-853.
11Barnes BO and Galton L. Hypothyroidism:
the unsuspected illness. Ty Crowell Co;
ISBN: 069001029X; 1976. 12Toft AD.
Thyroid hormone replacement – one hormone or
two? N Engl J Med 1999; 340:469-470.
13Franklyn JA. Long-term thyroxine
treatment and bone mineral density. Lancet
1992; 340(8810):9-13. 14Price Quote:
Walgreen’s Pharmacy –
Boca Raton
;
October 26, 2002
.
Dr.
Kenneth Woliner is a board-certified family
physician in private practice in
Boca Raton
. Though he often recommends vitamin
supplements, he does not sell them due to
conflict of interest concerns. He can be
reached at Holistic Family Medicine, 2499 Glades
Road #106A, Boca Raton, FL 33431; 561-620-7779.
E-mail: knw6@cornell.edu
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