Subclinical hypothyroidism (SH) has causes and symptoms similar
to those of overt hypothyroidism. This article describes SH
and explains why it should be treated.
In the early 1970s, when clinical laboratories developed blood tests to measure thyrotropin, which is also called thyroid stimulating hormone or TSH, the term subclinical hypothyroidism (SH) first emerged. SH refers to elevated TSH levels in patients with normal levels of thyroid hormone, both FT4 and FT3, associated with few or no symptoms of hypothyroidism. Prior to this time, doctors recognized that some patients with normal thyroid hormone levels had symptoms of hypothyroidism. These patients were said to have conditions of preclinical myxedema, compensated euthyroidism, preclinical hypothyroidism or decreased thyroid reserve. Today, it's accepted that most SH, like most overt hypothyroidism, is caused by autoimmune thyroid disease. Autoimmune hypothyroid disorders include: 1) a chronic condition of lymphocytic thyroiditis called Hashimoto's thyroiditis, which usually is accompanied by goiter; and 2) an atrophic form of thyroiditis called primary myxedema, which usually causes progressive thyroid destruction.
Subclinical hypothyroidism also occurs in patients with infectious, silent, or postpartum thyroiditis, patients on excessive doses of anti-thyroid medications, patients on lithium and other medications, patients with hypothyroidism who are on inadequate doses of replacement hormone, and patients with diminished thyroid function related to permanent treatment for hyperthyroidism.
THE TSH LAG
Normally, thyroid hormone production is regulated by a system known as the hypothalamic-pituitary-thyroid axis in which the hypothalamus situated at the base of the brain regulates thyroid hormone levels via the pituitary gland. When the hypothalamus senses that our thyroid hormone levels are too low for our body's needs, it orders the pituitary gland to release TSH. TSH, in turn, raises thyroid hormone levels by ordering thyroid cells to grow and produce more hormone. Likewise, when thyroid hormone levels rise, the pituitary stops secreting TSH and TSH levels fall. Through this mechanism, thyroid hormone levels are under pituitary control. However, the hypothalamus is savvy enough to know that our needs for hormone vary from day to day and sudden changes happen. So it proceeds slowly and orders the pituitary to take it slow.
Although TSH may start rising and become abnormally elevated before thyroid hormone levels fall below the range, it takes at least 6 weeks for serum TSH levels to accurately reflect thyroid status. Even with this lag, TSH levels are considered the best test to screen for thyroid disease. Under normal circumstances, an elevated TSH level is the best indicator of thyroid hormone deficiency.
Normally, the pituitary gland secretes TSH in pulses throughout the day, with peak levels produced at night. The rate of TSH production varies, depending on our general health, diet, exposure to stress, temperature, circadian rhythm, altitude and other needs. However, if thyroid function begins to decline due to autoimmune, surgical, or ablative destruction of the thyroid gland the, TSH level can reach 1,000 and still fail to induce production of sufficient thyroid hormone. Then, thyroid hormone levels are no longer maintained by pituitary control. The body requires exogenous (from outside of the body) thyroid replacement hormone. Eventually, after thyroid replacement hormone restores the body's levels, pituitary control is reinstated. Again, the pituitary pitches in to help when the hypothalamus notices thyroid hormone levels starting to rise and fall. In treated patients, unless interferences from autoimmunity or medications affect the results, TSH levels can again be used to reflect thyroid status.
TSH INFLUENCES
However, TSH levels can be influenced by other factors. For instance, when the immune system produces blocking TSH receptor antibodies that contribute to hypothyroidism, the TSH receptors (the cellular signaling system) on thyroid cells recognize these antibodies as if they were TSH. Consequently, thinking that we have adequate TSH levels in our blood, TSH production slows down and the serum TSH level is falsely decreased. TSH can also be falsely decreased by medications including dexamethasone and corticosteroids. TSH levels also rise for a week and then fall in conditions of non-thyroidal illness, including surgery, trauma or infection. TSH levels may be falsely elevated by test interferences caused by TSH antibodies, heterophile antibodies and anti-human antibodies. These interferences will be described further in an upcoming article on laboratory test interferences. It's important to recognize that a low or normal TSH doesn't mean that one can't be hypothyroid and a high TSH doesn't always indicate subclinical hypothyroidism. An evaluation of signs, symptoms and thyroid hormone levels is also needed.
Furthermore, a normal TSH level may not be normal or adequate for the individual. Normally, we all have optimal levels of FT4, and our TSH will vary as it works to keep FT4 stable. Since the TSH test was implemented its reference or normal range has changed several times with early tests using a range of 10-20 mu/L based on the TSH levels of hospital workers, many with undiagnosed thyroid disorders. The newer ranges use a better representation of the normal population. The current recommended reference range for TSH is 0.3-3.0 mu/L.
TO TREAT OR NOT
Over the last three decades, physicians and researchers have debated the significance of SH and questioned the need for treatment. This is partially because few long-terms studies of SH exist, and considering the early TSH range, there's no way to estimate its true prevalence. Has the incidence of subclinical hypothyroidism increased since the 70s or have newer, more sensitive TSH tests and changes to the reference range made this appear to be the case? Furthermore, because symptoms wax and wane in autoimmune disorders, TSH levels might be elevated one month and normal the next. Patients with roller coaster results may have been told their suspected thyroid condition had resolved and sent home. Thus, a wait and see approach prevails among some practitioners.
Recent studies have confirmed this notion that patients with both subclinical hypothyroidism and hyperthyroidism can spontaneously recover. One recent study confirmed that SH can improve or resolve months or years after the initial diagnosis. According to this study, remission is not related to age, sex, or levels of thyroid peroxidase (TPO) antibodies. However, levels of blocking TSH receptor antibodies were not measured and they are often the cause of subclinical hypothyroidism.
Unfortunately, treatment is often withheld in SH despite a well-documented list of associated symptoms. These include: elevated lipid levels, cardiac abnormalities, depression, congestive heart failure, latency of motor nerve conduction, increased intraocular pressure, arthralgia, and cognitive changes. For years laboratory workers have noted a high incidence of cardiac events in ER patients with subclinical hypothyroidism but not subclinical hyperthyroidism. A recent study by Walsh, et al. confirmed that subclinical hypothyroidism, but not subclinical hyperthyroidism, is associated with an increase in fatal and nonfatal coronary heart disease.
A more provocative study would be a determination of how many cardiac events occur among patients waiting for their doctors to decide if treatment for SH is needed.
References:
Diez JJ, Iglesias P, Burman KD, Spontaneous normalization of thyrotropin concentrations in patients with subclinical hypothyroidism. J Clin Endocrinol Metab 2005; 90:4124-4127.
Walsh JP, Bremner AP, Bulsara, MK, O'Leary P, Leedman PJ, Feddema P, Michelangeli V, Subclinical thyroid dysfunction as a risk factor for cardiovascular disease. Arch Intern Med 2005; 165:2467-2472.
Douglas S. Ross, Subclinical Hypothyroidism, chapter 84 in Werner & Ingbar's The Thyroid, A Fundamental and Clinical Text, 8th Edition, Philadelphia: Lippincott Williams & Wilkins, 2000.
The copyright of the article Subclinical Hypothyroidism in Thyroid Disorders is owned by Elaine Moore. Permission to republish Subclinical Hypothyroidism in print or online must be granted by the author in writing.
Thanks a lot Elaine , my wife is presenting typical symptoms of
hypothyroidism ( sweats, feeling cold, slower thinking, puffiness on eye
lids, muscle cramps, very high cholesterol levels - total chol 8.5. LDL
4.2, metrorrhagia ( 3x D&C ), vitilligo, anti TPO antibodies present
400, anaemia, mild hypertension).But her TSH level is within normal range
unfortunately ( this is witholding her GP to start the treatment). I am GP
myself and I can not sleep as her GP has not decided to put her on any
medication for hyperlipidemia or replacement of thyroid hormone. She was
examinned by specialist in LIpid Clinic - another blood sample was taken.
We will arrange apptm with endocrinologist soon. I am sure they will start
Levothyroxine ( I hope I mean :) ). But I am extremely concerned about my
wife and I feel we miss every single day of her maltreatment. I would be
gratefull if you would comment a bit . Dariusz Rygier , e-mail
rygier@mp.pl Thank you again for this article. regards.
Oct 27, 2008 11:10 AM
Elaine Moore :
Hi, Your wife's symptoms sound fairly classic. And several new studies
show the risk of heart problems in subclinical hypothyroidism. Two
things come to mind:
1) Although the TSH level has been lowered
three times since the test came out and recommendations for lowering it
further recently were recommended, many labs are still using the old range
of 0.4-4.5 mu/L that the kit manufacturers use. The lab logic here is that
the endocrinologists will know about the new recommendations and see that
the ranges are skewed. Labs (like where I work) that keep on top of things
lowered their ranges to 0.3-3.0 in 2003. Newer recommendations suggest that
levels higher than 2.0 indicate hypothyroidism. For many years, experts
like Larsen at Harvard have said that in the presence of thyroid
antibodies, a TSH higher than 2.0 shows a move into hypothyroidism. So the
range could be the main problem.
2) In atrophic autoimmune
thyroiditis, patients also produce blocking TSH receptor antibodies and
these are the main cause of thyroid failure. These (and also stimulating
TSH receptor antibodies) falsely lower TSH levels. The pituitary gland has
TSH receptors. TSH receptor antibodies are recognized by the TSH receptor
as if they were TSH molecules. Thinking there's adequate TSH when it's
actually antibodies, the pituitary stops or slows down on secreting TSH. So
TSH is falsely decreased. In this case, a normal TSH prevents further
testing. If an entire panel is done, often this "normal" TSH is
accompanied by low FT4 and/or FT3 levels. Then again, these levels might
fall within the reference range....but if they're too low for the body's
needs, symptoms of hypothyroidism develop. In thyroid function testing, lab
results aren't nearly as important as symptoms. Especially today, when the
methods we use are more likely to be affected by interfering substances
(like heterophile or other anti-human antibodies or antibodies to TSH, T4
or T3). I hope this helps. Best, Elaine
Nov 8, 2008 1:27 PM
Guest :
I am 32 yrs old, very fatigued, almost debilitatingly so,confused,
forgetful and my hands and other joints are increasingly sore. I also had
arecent very high cholestrol test( total 240 and ldl 170) My sister and
mother have hypothyroidism. My sister in fact is having a difficult time
getting her tsh within normal limits despite medication and both are having
significant weight issues. I have had my tsh done several times and it has
always been within normal limits, and have been told I am depressed. I
know something else is wrong. What is a good way to proceed to get some
resolution.
Nov 10, 2008 10:44 AM
Elaine Moore :
Hi, Many labs are still using the old references for TSH and this
causes many cases of subclinical hypothyroidism to be missed. Ask for
copies of your lab results. The new guidelines from 2003 recommend using a
range of 0.3-3.0 for TSH. Newer references suggest that a TSH higher than
2.5 indicates hypothyroidism. See what your TSH level is, and if it's
higher than 2.5 ask your doctor about tests for thyroid antibodies and
re-evaluating your results. You may need to see an endo or a doctor with
more experience treating thyroid disorders. Best, Elaine
Nov 14, 2008 5:28 PM
Guest :
Dear Elaine, Thank you so much for this article. It explains a lot of
things, primarily that I am not crazy! :) A month and a half ago I was
diagnosed as hypothyroid and was put on 50mcg of levothyroxine; my endo had
only checked for TSH though (it was 5.9), so last week I got the full
labs... everything was within range, even my TSH had already dropped to
2.97, but I have been feeling significantly worse since I started
treatment... I had all anti-TPO, anti-TG and TSI antibodies, but all within
range - all the while my symptoms have been all over the place, going from
(mostly) hypo to (partially) hyper at whim. I thought I was losing it,
because to me it didn't make sense, and no one has been able to explain
it... so, thank you so much for explaining. Would it be possible to
say a bit more on atrophic autoimmune thyroiditis? I have only been able to
find few things on it, and I think it sounds... familiar. It is so
frustrating that so many endos only look at numbers and dismiss the
symptoms, I suppose getting as informed as possible is the best way to deal
with this condition... Again, thanks so much for this article. I've
already printed it out as proof of my sanity :) Cal
Nov 27, 2008 12:43 PM
Guest :
Hi, Elaine.. i have been living with joint issues for 3 years, primarily in
feet.. mostly upon waking.. have seen 2 rheumatologist... done lots of
bloodwork.. ana is greater than 1:60.. tests for sle is neg and rh fator is
neg.. joint oain is getting worse, hands lower back, feet burn.. am still
trying to be active, tired all the time.. am not over wt.. eat healthy..
went to the doctor.. my tsh is now slightly high.. t3 t4 normal.. she
thinks i may have clinical hypothyroidism.. i am going to see a new
rheumatologist nextweek.. what tests should i ask for.. right now i take
advil 800 a day tyl arthritis 2 tabs a day.. pain is getting worse.. i eat
no imflamm foods.. exercise when i can, what can i do.. feel like i am
slowly dying.. oh i also have infetility.. 2 miscarriages, i have
endometroisis.. several gyne surgerys.. need help.. would love any advice
from anyone.. thanks m.
Nov 29, 2008 8:56 PM
Elaine Moore :
Hi, Your symptoms could very well be caused by subclinical
hypothyroidism. Please read the blog on subclinical thyroid disorders
on my website, elaine-moore.com, which explains subclinical hypothyroidism
in greater detail. It's important to have tests for FT4, FT3 and also
thyroglobulin, TPO and TSH receptor antibodies. According to the most
current recommendations, TSH levels higher than 2.5 are associated with
subclinical hypothyroidism. Since T4 and T3 are often falsely elevated in
women, it's important to test free hormone levels with the FT4 and FT3
tests. These tests measure levels of available thyroid hormone. Best,
Elaine
Dec 18, 2008 9:32 AM
Guest :
Hello!
I have been having symptoms for years of a thyroid
problem, but was not diagnosed with hypothyroidism until 2003. I have been
to several doctors, increasing and decreasing my synthroid. I have never
expierenced complete relief. I too have endometriosis (which i beleive is
connected to the thyroid problem), and have had 2 casearn births and
several gyne surgeries also. I just had my blood done and here are my
results. TSH is 5.13, T4 free is 1.5 and my TPO is 376. I was told there
is a bigger problem here. I suffer like most: hair loss, dry hair, dry
skin, heart palpatations, extreme fatigue, excessive and painful mentral
cycles, cloudy/slowed thinking, just don't feel well over all. I just don't
know what else too do. To top it all off i will be losing my health
benefits as of Jan 1 09. I do have do appointment with a new do 12/30 just
to see what they say. After that i am off to a low cost clinic for people
with no insurance. I am just not sure they will know what do either. I too
feel like i am slowing going down and never feel good. Losing time with my
family.. so frustrated!!!
Help!
Dec 18, 2008 10:55 AM
Elaine Moore :
Hi, It would be helpful if you had an FT3 test as well. This will help
your doctor decide what type and amount of thyroid replacement hormone you
need to be on. It would also help to have an FT4 by dialysis test. It's
possible that your FT4 is falsely elevated since it's usually lower with a
TSH of 5.0 and symptoms. Once you're on the right type of meds the clinic
should be able to renew your prescription. Best, elaine
Jan 4, 2009 4:32 PM
Guest :
Hi Elaine,
My 21 year old daughter has what we were told is
"Thyroid Syndrome". It sounds very much like Subclinical
Hypothyroidism. She has been treated with Levoxyl for the past several
years. She has a secondary condition called supraventricular tachycardia
and this last weekend she was hospitalized with atrial fibrillation. I
have read several articles that allude to heart problems due to her
hypothyroidism, but I do not get much from the doctors that there is a
connection. I am so frustrated. No two doctors agree!!! I have asked for a
referral to an endocrinologist, but her GP says that her treatment is
straight forward and does not need one. Can you help me with any
documentation that I can take to the cardiologist and her GP?
Jan 6, 2009 9:01 AM
Elaine Moore :
Hi, Cardiac problems often occur in hypothyroidism. If you do a search
on the library of medicine's search engine, www.ncbi.nlm.nih.gov/pubmed/
you'll see many different article abstracts. Another excellent resource is
the book Werner & Ingbar's The Thyroid. It has several chapters devoted
to cardiac disease in thyroid disorders. You can also find great
information on www.thyroidmanager.org, which is an online thyroid textbook.
If you read the chapter on hypothyroidism, you'll run across cardiac
symptoms. But, since you mention atrial fibrillation, it's important
to know that people with hypothyroidism, especially subclinical
hypothyroidism, can easily move into hyperthyroidism. It's important for
your doctor to run tests for FT3, FT4 and TSH. Because TSH lags at least 6
weeks behind thyroid hormone levels, a TSH alone can miss someone who's
moving into sudden hyperthyroidism. It's also something to be aware of when
new symptoms develop. If you check out thyroid manager, be sure to look
over the section on Graves' disease. See my website too at
www.elaine-moore.com Best, Elaine
Jan 13, 2009 2:03 PM
Guest :
The last two years I have had chronic bone loss in my hips and leg while
taking two different medications to stop the loss and build the bone.
Neither treatment plan worked. My doctor referred me to an endocrinologist
and my TSH score was 3.9, or in the normal range of 0.4 to 4.5, which is
higher then when my family doctor tested me two years ago when my score was
2.4. Along with 3.9 TSH score my antibodies were normal. I can't help to
believe that there is a connection between my TSH score increasing and my
bone loss increasing during the same time. Should my TSH score be viewed
as normal under this situation?
Jan 13, 2009 2:43 PM
Elaine Moore :
Hi, Several years ago, the recommendations were for changing the TSH
range to 0.3-3.0, and recently it's been recommended that the range be
lowered to 0.3-2.5 mu/L. Did your doctor check TSH receptor antibodies?
Blocking TSH receptor antibodies can cause hypothyroidism in atrophic
thyroiditis. Bone loss isn't a common feature of hypothyroidism
although hypothyroidism can interfere with calcium metabolism. You might
want to ask to have your vitamin D level checked as more than 50 percent of
the population are showing vitamin D insufficiency now that more tests are
being ordered. Vitamin D is needed for calcium absorption. Low vitamin K
levels will also contribute to bone loss. Best, Elaine
Jan 17, 2009 9:57 PM
Guest :
Hi Elaine, Thank for the article with lots of info on it. i am 31
year old female with TSH levels 14.2 , Free T3 - 4.06, Free T4 - 12.45 ,
Prolactin - 16.8, FSH - 5.5 , LH - 4.76) test was dont on 3rd day of my
periods.Kindly let me know what should i do??? I have gained lots of weight
, i am tired and get stressed very often... i am working out even though my
weight doesnt go away....Kindly advise me ..Send me an email with reply to
pavisriswapna@gmail.com
Jan 22, 2009 6:57 PM
Elaine Moore :
Hi, In 2003, the American Association of Clinical Chemists recommended
that the TSH range be changed to 0.3--3.0, and last year they wrote that
TSH levels higher than 2.5 suggested hypothyroidism. Most laboratories use
the reference or normal ranges that the testing kit manufacturer first set
up. Because it's expensive to run hundreds of samples to determine a new
reference range, most labs just continue to use these old ranges, assuming
that physicians will have seen information about the new ranges. Most
endocrinologists know that a TSH of 4.68 suggests subclinical or even overt
hypothyroidism depending on what your FT4 level is. The iodine in the
contrast dye can trigger autoimmune thyroid disease but usually it lowers
the TSH level and raises thyroid hormone levels in people predisposed to
Graves' disease. If you've ever been on lithium, you may know that it's
also a trigger for autoimmune thyroid disorders and because it displaces
iodine it's especially known for causing hypothyroidism. You might
want to see an endocrinologist or internist if you can't get your regular
physician to follow up on this. An osteopath used to treating thyroid
disorders is also a good choice. Best, Elaine
Jan 23, 2009 8:27 AM
Guest :
I just had a thyroid test yesterday and my TSH level was 4.68. According to
that laboratory, I am in the normal range, and they are basically telling
me "case closed". I have all the symptoms of hypothyroidism.
Weight gain that I cannot lose no matter how I diet or exercise, dry hair
that comes out in handfuls, dry skin, brittle nails, constant fatigue and
sleepiness, mood swings, abnormal and painful periods, depression. But they
won't budge on the lab results and even discuss the possibility of
treatment. Also, there are further complications. I read that having
any sort of test using radioactive dye can skew the test results. I had a
CT scan last week. Does this mean my levels were high because of the test?
I am sitting here not knowing if I have a disease, not knowing where to
turn to get some answers because these doctors use their level of
"normal" as the Bible and just won't help me. Lastly, I have
bi-polar disorder. Does this mean my symptoms are overlooked as part of
that condition? How can I find a doctor who's willing to look past the lab
result and help me?
Mar 3, 2009 9:02 AM
novbaby0 :
I am 52, I had a hystorectomy done 17 years ago with the doctor
reconstructing and leaving in one of my ovaries, 5 years ago I started
going through mentapause with no symtoms. since Nov 2008 I have become very
tired, I can not move my bowels without a strong laxative,but daily I do
take 2 stool softeners, metamusil and drink 2 large glasses of apple juice
and 10 large glasses of water, I have gained 12pds within a few weeks, only
in my stomach.( I look pregnant) I have not changed my diet, I eat very
little with each meal and healthy. my throat is very dry most of the
time.I have a very bad pain in my neck to the right back, a catscan was
done where they found nodules on my thyroid, my largest nodule was 1.1cm
there were multiple other ones that were very close to the same size. None
of them were dominant, I do not have an enlarged or easily palpable
thyroid. my blood work showed my TSH 3rd generation was 1.02 and said to be
within normal range and my TPO Antibodies01 were greater than 1000. my
endocronologist does not feel it is the thyroid and feels that he will
retake the thyroid ultrasound in late Aug 2009 but does not feel he needs
to do the blood test again. He states the I almost for sure have autoimmune
thyroid disease. I am at a loss, I still have the symtoms from above and
the doctor says that it is not caused from the thyroid because the levels
are within normal range. I am so confused and need answers and help self pay, no insurance in Southern Indiana
Mar 3, 2009 9:45 AM
Elaine Moore :
Hi, I'm sorry to hear you haven't been feeling well. Your
elevated thyroid antibodies show that you have an autoimmune thyroid
disorder. TSH suggests that your thyroid is functioning normally. It could
be that your multiple nodules have started secreting more thyroid hormone
and this corrected any hypothyroidism you might have had. It could also be
that your thyroid hormone levels are falling but the changes aren't yet
being reflected by your pituitary gland. TSH is a pituitary hormone. It
would be helpful to have your FT4 level tested. This test measures your
level of thyroid hormone. It can take 6 weeks for your TSH to reflect your
thyroid status. Usually, if TSH is normal, no further tests are done unless
you have thyroid antibodies. Since you do, it might be good to have this
other test. Best, Elaine
Mar 5, 2009 1:06 PM
Guest :
Hi, I am a 33yr. old female diagnosed with Multinodular goiter. I have
had 3 FNA's and it finally came back cancer free. My TSH test came back
normal but they have not done antibodies testing. I have a family history
of thyroid disease. I am still concerned because I have large masses that
appeared over night on the left and right (right side is larger 6cm x 4cm)
of the Supraclavicular area. CT scans show that the lymph node is normal. I
have many symptoms including: Weakness, lethargy, fatigue, Dry skin, Cold
intolerance, Constipation, Weight gain, Muscle cramps, Jaw/ear pain and
high cholesterol. The doctors tell me that the masses have nothing to do
with my thyroid but for some reason I feel that they still do. Have you
ever heard of thyroid causing masses in the Supraclavicular area?
Thank you, Brandy mastiffred@yahoo.com
Mar 9, 2009 11:23 PM
Guest :
RESPECTED SIR,MY WIFE AGE IS 24 YEARS AND HER 4MONTHS AGO HER TSH WAS 14
WITH NORMAL T3 AND T4.DOCTOR HAD STARTED THYROXINE 50MCG 1 OD.NOW HER TSH
IS 4.SHE COMPLAINS OF ARTHALGIA,PALPITATION,DRY SKIN,WEAKNESS AND LOSS OF
CONCENTRATION.DOCTOR HAD SAID TO CONTINUE SAME DRUG.SHE ALSO SUFFERING FROM
ALLERGIC BRONCHITIS.I WANT TO ASK YOU WILL SH AFFECT HER FERTILE LIFE AND
WHAT PRECAUTION SHOULD I TAKE IF SHE GOT PREGNANT.ALSO WHEN WILL HER
SYMPTOMS LIKE PALPITATION,DRY SKIN,WEAKNESS WILL DISAPPEAR.KINDLY REPLY ON
dr3vedi@gmail.com
Aug 25, 2009 4:04 PM
Elaine Moore :
Hi, I hope your doctor isn't monitoring your levels with TSH alone. To
determine the best type and amount of replacement hormone, it's good to
also have FT4 and FT3 levels. Also, there's lots of controversy over
the TSH range. Most laboratory scientists and thyroid specialists agree
that the range needs to be lowered. In 2003, the American Association of
Clinical Chemists recommended the range be lowered to 0.3-3.0. Last year
thyroid specialists agreed that the high end of the range should be between
2.0 and 2.5. A large nutrition study showed that most normal adults have
TSH levels that run between 0.3 and 1.0 mu/L. With your symptoms and
increase in TSH, most doctors would run FT4 and FT3 levels and make sure
that these levels aren't too low for your body's needs. Even if they're
within range, they can be too low. For instance, with a range of 0.8-1.8
ng/dl for FT4, most people feel their best with an FT4 that's at least
1.5. Best, Elaine
Aug 29, 2009 7:45 PM
Elaine Moore :
Hi, the usual range for FT4 is 0.8-1.8. The thyroid textbook, Werner
& Ingbar's The Thyroid has lots of information on optimal thyroid
hormone levels. You can also try looking in the online textbook
www.thyroidmanager.org Your doctor should be able to tell from looking
at your levels that they could be higher and still within range. Symptoms
of hypothyroidism with your labs suggests that a higher dose of replacement
hormone could help. Best, Elaine
Sep 17, 2009 10:32 AM
Guest :
Hi Elaine, Thanks for this article! I just discovered yesterday (!)
that some blood work I had done in January showed that my TSH level was 7.2
and my antimicrosomal antibodies were 160 (all other levels are normal).
How worried should I be that I may have SH? My biggest concern is that I am
four months pregnant with twins...Is this something I should address with
my GP/OBGYN/both?? Any advice on what kinds of questions I should ask and
what kind of treatment I should expect? I understand there can be risks to
me and my babies - if I start treatment at this late stage, will it still
be helpful? Sorry for all the questions! Many thanks.
Sep 17, 2009 11:21 AM
Guest :
Hi Elaine, Thanks for this article! I just discovered yesterday (!)
that some blood work I had done in January showed that my TSH level was 7.2
and my antimicrosomal antibodies were 160 (all other levels are normal).
How worried should I be that I may have SH? My biggest concern is that I am
four months pregnant with twins...Is this something I should address with
my GP/OBGYN/both?? Any advice on what kinds of questions I should ask and
what kind of treatment I should expect? I understand there can be risks to
me and my babies - if I start treatment at this late stage, will it still
be helpful? Sorry for all the questions! Many thanks.
Sep 22, 2009 12:54 PM
Elaine Moore :
Hi, With your TSH at 7.2 you probably need to be on replacement
hormone. Your elevated TSH suggests that FT4 and FT3 may not be high enough
for your body's needs even if they're within range. Your babies' needs are
covered first so they should be ok. It's important too to have your thyroid
hormone levels monitored every month during pregnancy when you have levels
that are off. Best, Elaine
