The TSH Thyroid Function Test

When Thyrotropin Isn't The Gold Standard

Mar 12, 2007 Elaine Moore

The TSH test result is an excellent tool for screening new patients for thyroid disease. But in some cases of autoimmune thyroid disease, the results can be misleading.

The hormone thyrotropin, which is also known as thyroid stimulating hormone or TSH, is produced by the pituitary gland. The pituitary gland regulates thyroid hormone levels by secreting more or less TSH. Consequently, low levels of TSH are seen in hyperthyroidism, and high levels are seen in hypothyroidism. Usually, blood levels of TSH can detect abnormal thyroid function.

The Hypothalamic-Pituitary-Thyroid Axis

The hypothalamus at the base of the skull is considered the true master gland since it controls the other endocrine glands, including the pituitary gland. The hypothalamus monitors all of the body’s hormone levels. When slight abnormalities occurs, the hypothalamus engages other organs to correct matters.

Normally, the pituitary gland secretes TSH in small pulses throughout the day. TSH orders follicular thyroid cells to grow and produce thyroid hormone. Without adequate TSH (due to a pituitary or hypothalamic malfunction as is seen in central hypothyroidism) the thyroid gland normally couldn’t produce adequate thyroid hormone.

The hypothalamus secretes a hormone known as thyrotropin-releasing-hormone or TRH. TRH directs the pituitary gland to secrete TSH. When the hypothalamus notes a rise in thyroid hormone levels it secretes less TRH, causing the pituitary to secrete less TSH. When the hypothalamus sees that thyroid hormone levels are falling, it releases more TRH, which raises TSH levels and, in turn, thyroid hormone levels.

The Axis Has Its Limits

In thyroid disease, the axis can’t fully correct thyroid hormone levels. In Graves’ disease, stimulating TSH receptor antibodies (also known as thyroid stimulating immunoglobulins or TSI) stimulate the thyroid receptor to produce more thyroid hormone. Acting in place of TSH, TSI antibodies order thyroid hormone production even when TSH falls to non-detectable levels. In Graves’ disease, thyroid function falls under immune system control rather than hypothalamic regulation.

In hypothyroidism, damaged or defective thyroid cells can’t produce adequate thyroid hormone. Even with a steadily rising TSH, thyroid hormone levels remain low.

Benefits of TSH Testing

As soon as the pituitary gland is alerted that thyroid hormone levels are changing, it adjusts secretion of TSH accordingly. Normally, TSH levels rises to abnormally high levels before thyroid hormone (FT4 and FT3) levels fall below the normal range. Similarly, TSH levels fall below the reference range before thyroid hormone levels rise above the normal range.

Read on

Thus, in screening for thyroid disease, the TSH test is the best early indicator of thyroid dysfunction. If the TSH level is normal, thyroid function and levels of FT4 and FT3 are usually also normal. In screening new patients, the TSH test is considered a cost-effective gold standard for evaluating thyroid function.

If the TSH result is abnormal, the FT4 level is tested. If FT4 is normal, the FT3 level is tested. In some thyroid disorders, particularly Graves’ disease and toxic multinodular goiter, T3 is released from thyroid cells at a high rate, and levels of FT3/T3 become elevated before FT4 levels rise. Because T3 is nearly 5 times as potent as T4, even a slight rise in FT3 levels can cause symptoms of hyperthyroidism requiring treatment.

Subclinical Thyroid Disorders

In subclinical hypothyroidism and subclinical hyperthyroidism, thyroid hormone levels remain within the normal range while TSH is abnormal. Presumably, thyroid hormone levels may have changed slightly and been corrected by the pituitary. In subclinical disorders, thyroid function remains normal, but the abnormal TSH level suggests that a problem may be developing.

Because TSH only affects thyroid hormone production, an abnormal TSH doesn’t cause physiological changes related to hyperthyroidism or hypothyroidism. Symptoms of thyroid disease are caused by low or high thyroid hormone levels. However, if the levels are within range but too high or low for the individual’s bodily needs, symptoms of hyperthyroidism or hypothyroidism can occur.

Subclinical disorders are difficult to confirm. Changes in temperature, diet, altitude, general health, medications and stress influence TSH secretion. TSH also falls in illness (euthyroid sick syndrome, endogenous depression) and during treatment with corticosteroids or dexamethasone. And, as mentioned, TSH can fall when the pituitary gland or the hypothalamus aren’t functioning properly.

In autoimmune thyroid disease, TSH levels also fall in people with TSH receptor antibodies (TRAb). Both the stimulating TRAb seen in Graves’ disease and Hashitoxicosis, and the blocking TRAb seen in atrophic hypothyroidism are recognized by the pituitary gland as if they were TSH. Erroneously thinking that blood levels of TSH are adequate, the pituitary gland secretes less TSH. For this reason, patients with Graves’ disease may have low TSH levels even after they become euthyroid (normal thyroid function). Patients with Graves’ disease are considered euthyroid as soon as FT4 falls within range.

Reference Ranges:

Controversy surrounds the normal TSH range. Early ranges based on results of female hospital workers were much too high. Since, the range has been lowered several times.

The current recommendations are for a TSH reference range of 0.3-3.0 mu/L with levels below 0.3 suggesting hyperthyroidism and levels above 3.0 suggesting hypothyroidism. However, as with any clinical laboratory test, correlation must be made with other laboratory results, clinical signs and symptoms, and a careful medical history.

Resources:

GJ Canaris, NR Manowitz, G Mayor, EC Ridway, The Colorado Thyroid Disease Prevalence Study, Archives of Internal medicine;160: 526-534.

Elaine Moore, Graves’ Disease, A Practical Guide, Jefferson, NC; McFarland and Company Publishers, 2000.

Henry Ogedegbe, Thyroid Function Test: A Clinical Lab Perspective, Continuing Education Course, Medical Laboratory Observer, February, 2007: 10-18.

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43 Comments

Comments

May 14, 2007 7:10 PM

Teresa :

I had RAI I-131 to "treat" graves twenty years ago. Now, my levels are all low... TSH and Free T3 and Free T4. I have been on either synthroid or armour since the RAI (armour right now) but my labs are now ALL low. How can that be? The doc wants to reduce, reduce, reduce becasue the TSH is near zero, but the Free's are low too! I have the symptoms of Hypo and I just feel like I cant find a doc who knows what to do with me! I am doctor hopping, and it isnt helping matters at all. Might this pituitary related? Or adrenal? HELP! I cant lower my meds. That isnt the answer! I'm already so hypo. These doc's are going to kill me with their lack of information on this.

May 15, 2007 6:36 AM

Teresa :

Thanks for any opinions.

May 15, 2007 9:38 AM

Elaine Moore :

Hi,
I replied to the email you sent me, but in case you didn't get it, you're considered euthyroid or normal after in treated Graves' disease when your FT4 is in the normal range. There have been numerous articles in Laboratory and Medical Journals explaining this, but unfortunately some doctors are still confused by this.
At one time it was thought that our becoming dependent on replacement hormone after RAI caused a disruption in the pituitary-thyroid-hypothalamic axis, which, in turn, caused a low TSH.
But since the studies of Brokken in 2003, which have been published in Clinical Thyroidology and Thyroid journals, it's known that the pituitary gland has TSH receptors that get confused by our TSH receptor antibodies. Thinking that we have adequate blood levels of TSH when we actually have high blood levels of TSH receptor antibodies, the pituitary stops secreting TSH regardless of our thyroid status.

And over time we begin producing more blocking than stimulating TSH receptor antibodies. These cause hypothroidism to worsen with levels typically falling up to 10 years after RAI and then necessitating total replacement hormone, which is typically 3 grains Armour. Best, Elaine

May 7, 2008 10:45 PM

Guest :

hi i have been in remission 6mths due for blood test now. i was taking neo merczole 2d for 18th months. I WEIGH 55.2KILOS 1.71M TALL in good health. Working in pharmacy retail for 22yrs. i do get the running feeling,headaches, chest infections problems. articles and commets are intresting

Aug 25, 2008 8:19 PM

Guest :

I was told I had an underactive thyroid after having my blood tested. TSH was 1.39. T3, Uptake was 29. T4, Total was 6.6 and T4, Free was 1.9. I was placed on 88mcg of synthroid. I am not confident that I actually need synthroid and I'm unable to find what the "normal" range is for T3 and T4. Can someone please tell me if I should be taking the synthroid or if I was misdiagnosed? Thanks,
Jan

Aug 25, 2008 8:40 PM

Elaine Moore :

Jan,
The reference range for T4 is 5.6-13.7 mcg/dl and for T3 it's 80-180 ng/dl;
The range for TSH is 0.3-3.0 mu/L
The range for FT4 is 0.8-1.8 and in some labs it's 0.8--2.0.

The FT4 result is more accurate than the total T4 result as the T4 test measures free hormone and the proteins that carry it. In this form, thyroid hormone is inactive.

I agree with your concern. Best, Elaine

Sep 3, 2008 5:56 PM

Guest :

Hi,
I have pretty much every symptom of hypothyroidism. I have had depression for several years that is not responding to treatment. I also am overweight as is my entire family and I gain weight very easily. I was on birth control and prozac and stopped both thinking they were the cause of my weight gain but since, have gained another 5 or 10 pounds. I diet regularly and eat no more than 1500 calories a day on a normal day. I could use a little more exercise but I work as a nurse full time. I am also very sensitive to cold, sensitive to medications, have constipation, dry skin, hair easily falls out, fatigue, and slight anemia that my Dr. assumes is iron deficiency but it is only a low H/H and RBC. No abnormalities in iron, ferritin, or other MCV or MCHC. My TSH was 2.46 which was up about .4 since a year ago. Could my thyroid be causing my symptoms? My doctor will not do any further testing so I wanted to get some other advice.
Thanks
Sarah

Sep 7, 2008 8:12 PM

Guest :

I am a 43 year old woman. I was mildly hyperthyroid for almost 10 years until last fall when (probably due to alot of stress), my thyroid became very hyperactive. I started a very low dose of Tapazole (5 whatever the measurement is/day) last winter and after roughly 3 weeks, had a rare reaction. After vomiting and itching for weeks (all ignored by my doc who insisted it couldn't be my medication), I went into liver failure.
After 5 days in the hospital and 2 months out of work, I started to get my life back, although my thyroid was still quite fast. I couldn't do RAI (i had a CAT scan with contrast when hospitalized) so I read the net and subsequently decided to give up diet soda. I admittedly drank way too much (12-20 cans/day). Within a few weeks, I felt much better and my T3 and T4 levels, according to my doctor were way down, almost to normal.
After a few months, I mistakenly tried to drink a little soda in moderation (a can or two a day) but my thyroid again sped up a little. Now, my (new) doctor wants to do RAI even through my T3 and T4 levels are basically normal and I feel great. Her reason is that my TSH is undetectible and she is afraid that my thyroid will speed up again. After reading what a difficult time people who go through RAI to treat Graves often have with feeling hypo, I am very wary. How do I convince this doc, whom I really like, that low TSH is not a good reason to wipe out my thyroid.
Any thoughts?

Sep 8, 2008 9:06 AM

Elaine Moore :

Dear Guest,
Regarding diet soda, in many people aspartame in diet soda triggers autoimmune hyperthyroidism and also seizures, MS, and other disorders. Avoiding it helps induce remission.
With normal thyroid hormone levels and a low TSH, the condition is called subclinical hyperthyroidism. This disorder is watched and generally not treated. I wrote another article on TSH on this site last week and I wrote a blog on subclinical hyperthyroidism on my new website at www.elaine-moore.com last week that explains this.
About 10 years ago Dr. Janet Hull had a similar experience to yours and was diagnosed with severe Graves' disease as a result of drinking diet soda with aspartame. She went on to write a book on this.
TSH takes a very long time to fall after one develops Graves' disease. Once the thyroid antibodies that caused the problem fall, TSH will start to rise. Using radioiodine would be pretty extreme. Best,Elaine

Sep 24, 2008 9:35 PM

Guest :

After 15 years of being treated for hypothyroidism my dosage got smaller and smaller until this past January when I was taken off the medicine (an endocrinologist had told me 4 years ago he'd have taken me off then if I hadn't been trying to get pregnant-we now have an 19 month old daughter). Now, after being off the medicine I've begun experiencing the same symptoms I used to have when they needed to lower my meds (palpitations-my resting heart rate has been at least at 90 for 6 weeks now!)-but now there are no meds to lower. 2 weeks after symptoms started I got pregnant and was unable to take the iodine uptake test my new doc wanted for me. But my numbers "look good": TSH is .51, T3 is 98 and T4 is 1.2 and the doc says she "can't attribute my problems to my thyroid. I know my body, and I've had these symptoms so many times before-I don't know what to do since there's no meds to lower! I just want my heart rate to go down (from fixing the problem-not beta blockers!). Are there natural options for someone like me, in their first trimester or any hope of help? Any help, opinions would be greatly appreciated!!

Sep 25, 2008 7:50 AM

Elaine Moore :

Hi,
Your levels are on the low side. The reference range for T3 is 80-180 and for FT4 it's 0.8-1.8
There are drugs such as methimazole that are used to lower thyroid hormone levels but you don't need them. They'd easily cause hypothyroidism.
Symptoms in early pregnancy can be very similar to those of hyperthyroidism because the pregnancy hormone, beta hCG, is very similar to TSH. It can stimulate the thyroid gland to produce extra hormone needed for fetal growth.
It's great that you're monitoring your levels carefully. During the second half of pregnancy increased estrogen levels cause thyroid hormone levels to fall. Most women on replacement hormone need additional replacement hormone during the second half of pregnancy. Best, Elaine

Oct 7, 2008 6:28 AM

Guest :

Vikky
I have an underactive thyroid & am currently taking 175mg per day of levothyroxine. My previous blood test showed TSH at 1.7. My last blood test shows my TSH to now be 9.8 & T4 14.3. I have not missed any tablets. Any ideas !

Oct 7, 2008 7:32 AM

Elaine Moore :

Total T4 can be falsely increased, especially if you're on estrogens. It sounds like your need for thyroid hormone has increased. This can be due to cooler temperatures, increased estrogen levels, other hormones, and a worsening of the autoimmune process. It would be good to have tests for FT4 and FT3. These are better indicators of your thyroid status and will show what type and amount of replacement hormone would work best for you. Take care, Elaien

Oct 26, 2008 3:28 PM

Guest :

I am a postmenopausal woman aged 49. I went through menopause at age 42. I have Hashimoto's and have had intermittent episodes of hyperthyroid symptoms with feeling normal in between for the last 3 years (since I was diagnosed). The hyperthyroid symptoms are generally an easily-racing heartbeat, occasional SVT's, and varying levels of anxiety.

Over the years I have had a good number of TSH/FT4/FT3 tests. Everything is always normal except (sometimes) my TSH. It goes up and down between 2.5 and 6.3. The last test I had was 2.95. It has often been just around/over 3.0. But I have no symptoms of hypothyroidism except for really dry, wiry hair and funny fingernails. :)

I am not on any medications, haven't taken any thyroid replacement to date.

I assume I don't need any thryoid replacement, but I am concerned about my heart rate and anxiety periods. I often wake up at night with my heart racing really fast and usually have a resting heart rate 80 beats a minute (which is uncomfortable). I usually "feel" it more than I should. It really gets going when I work out.

Should I be concerned about what this is doing to my heart? Would taking thyroid replacement be a good idea at this time? I also have mild MVP.

Oct 27, 2008 10:07 AM

a s :

I am a 49 year old female. Hit menopause at age 42. I have had intermittent periods of hyperthyroid symptoms since I was diagnosed with Hashimoto's 3 years ago including rapid heartbeat, SVT episodes, and anxiety from time to time. I have not had any of the symptoms of hypothyroidism except for very dry, wiry hair and weird fingernails.

My blood test level results from labwork taken over the last 3 years show all normal levels except, often as not, my TSH, which bounces up and down between 2.5 and 6.3 - often just around/above 3.0. My last test was 2.95. I have never been on thyroid replacement medication nor am I taking any medication at this time. Cholesterol levels are good.

My concern is my rapid heartbeat. It often beats at 80 beats a minute when resting, which, although normal, is uncomfortable. I can "feel" it more than I think I should. I often wake up in the middle of the night with a racing heartbeat and feelings of anxiety. My heart really gets going when I work out - whether weights or aerobics.

Should I be concerned about the effect this is having on my heart (I also have mild MVP)? Is this probably related to the Hashimoto's? It just works so hard much of the time. I don't think I need to be on hormone replacement, but am wondering if it, or maybe a beta blocker, would be beneficial on my heart and reduce the "wear and tear" on my heart.

Oct 27, 2008 10:39 AM

Elaine Moore :

Hi,
Oddly enough, many symptoms of hyperthyroidism and hypothyroidism overlap. Some symptoms seen in both conditions include palpitations, anxiety, and sleep disturbances.
Palpitations, which sound like what you're describing, are generally considered harmless although you'd want to talk to your doctor about this. Hypothyroidism, even subclinical hyperthyroidism (elevated TSH, normal thyroid hormone levels) is associated with cardiac problems and elevated diastolic (top number) blood pressure. A beta blocker can help reduce palpitations and might be helpful for you. For more information on subclinical thyroid disorders see my website at elaine-moore.com.
Best, Elaine

Oct 27, 2008 11:16 AM

Elaine Moore :

Hi,
Please read the last comment I wrote about palpitations. I think this is what you're describing. Also, here's a comment I just sent to someone on another of my thyroid articles regarding why lab tests may be normal despite symptoms.

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

Jan 16, 2009 12:17 AM

Guest :

Hi there, my name is Chriss. First I would like to start off by mentioning that I had been referred to a physical medicine specialist back in Dec'06. At that time, I had been experiencing several symptoms that related to Lupus, Fibromyalgia, Chronic Fatigue Sydrome, etc., that started after a serious car accident in Nov'04. Symptoms worsened over many many months. As it turned out, I received an official diagnosis of Fibromyalgia in June'07. This brings me to my question - blood work was done by the physcial medicine specialist and it's my TSH result I am seeking clarity on. In early Dec'06 my TSH result was 1.712 mIU/L (w/normal range listed on paper at .50 - 4.2). Then, I was in a 2nd car accident in Sept'07 which flared my fibromyalgia, and a cple mths went by with no improvement at all, so my phys. medicine doc had some blood work done again (this was Nov'07 - 11 mths after first blood tests) and in less than a yr my TSH result went up to 3.049 mIU/L, but nothing was said about it. The reason I am questioning it now, is because there has been no improvement in my fibromyalgia since the 2nd accident, it feels like my fibro. is constantly in a flare-up and my fatigue just keeps getting worse. My skin and hair has become noticably dryer & older looking (if that makes sense) in the last 8mths or so, and I've gained 15+ lbs last 5 mths. My insurance company forced me into a phys. rehab. program early Dec'08 & within 2-3 days of rehab starting, my joints (hands, wrists, fingers, elbows/forearms, knees, ankles/feet) started aching, throbbing & cramping, etc), fatigue was much worse than norm., and swelling started in my lower extremities and my face w/puffy eyes, and top of hands, legs & very low back itch LOTS w/bumps/hives top of hands (not allergies). On 6th day of rehab (2hrs/day Mon-Fri -cardio, stretching & strength exercises) started having vertigo w/lightheadedness, disorientation, dizziness and couldn't go back to rehab -per my specialist. Then 10 days later I ended up in hospital w/severe swelling in my lower legs, along w/tingling, pins&needles, numbness (that also bothered one of my arms), w/dizziness, weakness and joint tenderness (around knees especially) being so bad that I needed help to walk to/from bathroom, etc. No blood work was done aside from checking liver & kidney function, and CT & MRI results were normal. Five days later a rash appeared on my lower legs and lower abdonmen, it comes and goes. Could this be my thyroid???

Jan 16, 2009 7:43 AM

Guest :

Hi, it's Chriss again. Sorry but I forgot to mention the chills I sometimes get at night as well, along with night sweats (though that symptom is less often). I'm almost always cold or chilled and usually wear my socks to bed, then sometime through the night I take them off when my feet feel warmer. My hands are almost ALWAYS cold, my 13 yr old son comments often about how cold my hands are. The skin and cuticles around my finger nails are SO dry and they crack often....and my finger nails themselves are dry/brittle w/many of them warped or growing downward (I'm very self concious about my fingernails because they're weird looking). All of these symptoms have been present for the last 2+ yrs I'd say, so the first post I sent lists more recent symptoms in the last yr - which I'd also like to add to the recent symptoms as well that I had forgotten to mention. In the last 4-5 mths my period has also been much heavier and longer than usual, with break through bleeding one month...which is strange because I'm on birth control and my period for yrs was only 2-3 days with light flow. Also, I've noticed (as well as my son) that I'm much more irritable/moody 3-5 days before my period and during as well, and even in general w/crying episodes here and there. My eyes have also been blurry which seems to be worse in the mornings, but also in general as well, and they're often dry and itchy...I find I'm rubbing them quite a bit. My headaches have also been worse, more intense than usual, with shooting pain sometimes in my right eye. My lips as well have been extremely dry, no matter what season it is.

So again, I wonder if my thyroid has anything to do with all these symptoms, as well as the ones in my first post. I've not had my TSH level tested since the Nov'07 blood work, but I see my specialist next week and plan on requesting a full blood workup again. I don't believe I've had the T3 & T4 tests done, and wonder if I should ask about those even though I am on birth control pills? Any feedback, suggests or insight you may have, would be greatly appreciated. Thank you, Chriss.

Jan 16, 2009 9:22 AM

Elaine Moore :

Hi Chriss,
Your symptoms all point toward hypothyroidism. A lot can change in just a few months so it's definitely time to be retested.
Ask for a TSH, FT4 test and a test for thyroid antibodies. I usually mention FT3, but this assay has been running high lately and I'd hate to see you end up with a false positive results. Total T3 and T4 (T4 and T3 tests) will be falsely elevated by your oral contraceptives so don't get these. Best, Elaine

Jan 19, 2009 8:27 AM

Guest :

hi i just reacentley had a blood test and my tsh was 17.5 what does this mean my gp said come back in two weeks to have another one but i have been struggling to swallow and have avery bad pain in my neck and back can any one help .vicky

Jan 19, 2009 8:46 AM

Elaine Moore :

Hi Vicky,
A TSH higher than 3.0 suggests hypothyroidism. There are several causes of hypothyroidism with the most common disorder being the autoimmune disorder Hashimoto's thyroiditis.
Another common cause is a viral or infectious or silent form of thyroiditis. This usually causes a period of hypothyroidism or hyperthyroidism lasting about 2 months followed by a similar period of the other thyroid disorder.
Your doctor might want to see if your level has swung the other way in a few weeks and asked you to wait for this reason.

Any form of thyroiditis (thyroid inflammation) can cause a sore throat and pain in swallowing or a hoarse voice if the thyroid gland becomes enlarged (goiter). Goiters aren't always visible and are more likely to cause symptoms when they're not visible and the gland is situated further back in the neck.

Pain isn't common and it can be a sign of subacute thyroiditis, which is caused by infection and needs proper treatment.

You should probably call your doctor's office and report your new symptoms. Ideally, your doctor would order a CBC to look for signs of infection and along with tests for FT4 and FT3 to see what your actual thyroid hormone levels are. You could also go to an urgent care facility if need be, but it's a good idea when there's pain to get things out sooner rather than later. Best, Elaine

Jan 21, 2009 2:06 AM

Guest :

Jan 21, 2009 2:14 AM

Guest :

Jan 21, 2009 10:16 AM

Elaine Moore :

Hi Chriss,
Hypothyroidism can cause many different symptoms although most people experience a few predominant symptoms. Joint pain, rash, urticaria, neuropathy (tingling in extremities), inability to regulate body temperature, etc. are all symptoms. It's important to have a TSH, FT4, FT3, and tests for thyroid antibodies. If these are normal, you'd want to have a workup for thyroid hormone resistance. Best, Elaine

Feb 21, 2009 2:33 AM

Guest :

What if you can't have the T3 and T4 tests done? What other tests can be done to see if you have a thyroid problem?

Feb 21, 2009 2:39 AM

Guest :

Hi Elaine. Can you have the same kinds of symptoms if ur in pre-menopause? All thyroid tests came back normal so I've asked my doctor about hormone testing but he doesn't think that's an issue. A woman knows when her body isn't feeling right. The only tests that haven't been done are my hormone levels and all other blood work and other tests have been normal, but I just know something is going. Yet I'm being told there's nothing and that I'm too young for menopause (I'm 38).

Feb 21, 2009 11:36 AM

Elaine Moore :

Hi,
If you're not on any thyroid medications, TSH is a good screening test for diagnosing new cases of thyroid disease in most people. If TSH is normal and you have a family history of thyroid disease or strong symptoms of thyroid disease, most doctors will order FT4 and FT3 tests and also tests for thyroid antibodies. Otherwise, a high cholesterol level can suggest hypothyroidism and years ago cholesterol tests were used to give an idea of thyroid function. But nothing compares to thyroid function tests, FT4, FT3 and TSH. Best, Elaine

Feb 21, 2009 11:42 AM

Elaine Moore :

Hi,

Symptoms of peri-menopause can start occurring in women in their late 30s. Any related changes might not show up in blood tests. Most blood tests used, like FSH and LH, are used to confirm menopause in women who stopped having periods.
You might want to do a search on estrogen dominance and see if any of those symptoms fit. In this case, women often use topical progesterone creams to help reduce symptoms. And if you only had a TSH and it was normal now, you might ask about having the TSH test repeated in 3-6 months since symptoms can show up before lab results become abnormal. Also, find out the results of your TSH test. Many labs are still using the old higher reference ranges for TSH. If your TSH level is higher than 3.0 this could suggest hypothyroidism. Best, Elaine

May 6, 2009 8:46 PM

Guest :

my friend has post RAI hypothyroidism, taking thyroxine tablets as supplement. on regular blood test, doctor said her TSH was a bit high, but T4 was normal. she has no symptom. doctor still step up the dose of thyroxine. i heard that TSH rises slow. When should we arrange blood test again? just test TSH or test T4 too? any special precaution on diet? Please advise. thanks

May 7, 2009 9:07 AM

Elaine Moore :

Hi,
the best test for monitoring thyroid hormone levels after RAI is the FT4 test. The free T4 (FT4) measures available levels of thyroid hormone. Your friend should also have an FT3 level because many of us fail to convert T4 into T3 properly after RAI.
T3 is much more potent than T4. Your friend's TSH could be high because her FT3 is low and/or because her FT4 is too low for her body's needs.

TSH does lag about 6 weeks behind thyroid hormone levels. If your friend has been on a certain dose for a while it's not unusual for adjustments to be needed. After RAI, hypothyroidism steadily worsens. One year after RAI, the average dose of levothyroxine is 0.1 mg (100 mcg) whereas 6 years after RAI, the average dose is 175 mcg.

Increasing the dose of replacement hormone is a good idea when TSH is elevated but both the FT4 and FT3 levels are needed to figure out what type and amount of replacement hormone is best. Many people use both T4 (levothyroxine) and T3 replacement hormone.

The T4 and T3 tests aren't as good as the FT4 and FT3 levels. T4 and T3 measure inactive hormone that's bound or linked to carrier proteins. Changes in levels of these proteins affect the results. Estrogens cause a rise in these proteins so levels of T4 and T3 are often falsely elevated in women. Best, Elaine

May 8, 2009 6:53 AM

Guest :

You state: "TSH does lag about 6 weeks behind thyroid hormone levels." Can you cite a reference or two to support this? I have read several texts on endocrinology (Endocrinology in Clinical Practice -- 2003 by Harris-Bouloux to name one) but they do not mention a lag -- probably because it is so basic and commenly known. But after many hours of searching, I have been unable to find credible confirmation. Thanks!

May 8, 2009 9:05 AM

Elaine Moore :

Hi,
The 6 week lag for TSH is mentioned in Clinical Diagnostic Laboratory Books such as Clinical Chemistry volumes by Tietz and also in Endocrinology, Test Selection and Interpretation, 2nd Edition by Delbert Fisher.
I haven't looked there recently but you could also look in www.thyroidmanager.org
Best, Elaine

Jul 13, 2009 5:47 PM

christy lemaster :

I had my Tsh checked and is was 5.13 in December I had it checked and it was 1.99, and my t4 was 14 something and my free t4 was 0.50. In less than a year my TSH has jumped this much, My t4 was 12 something this time and I haven't got my results yet on my free t4. I have all the classic signs, I have alot of hair loss and its so dry. My doctor is telling me that this level isn't high enough to put me on the medication yet Is this Normal?

Jul 14, 2009 9:30 AM

Elaine Moore :

Hi,
The American Association of Clinical Chemists recommends using a TSH range of 0.3-3.0 and last year they suggested the high end of the range be lowered to 2.5.
If you're on estrogens your T4 level will be falsely elevated. Your doctor may be confused by this level, which measures inactive hormone. If your FT4 was only 0.5 before it may be even lower now. The usual reference range is 0.8-1.8 and your level shows you don't have enough thyroid hormone for your body's needs. Best, Elaine

Jul 15, 2009 3:06 PM

Elaine Moore :

Hi Christy,
Yes, you're hypothyroid and most endocrinologists would start you on thyroid hormone. Elevated lipid levels are caused by hypothyroidism.

When you don't have enough thyroid hormone for your body's needs, your pituitary gland secretes more TSH trying to correct the problem. Normally, TSH orders thyroid cells to produce more thyroid hormone. Your elevated TSH is a sign that you're hypothyroid. Best, Elaine

Aug 3, 2009 8:54 PM

Elaine Moore :

Hi,

TSH is a pituitary hormone that helps to regulate your thyroid hormone levels (FT4 and FT3).

Normally, TSH is secreted throughout the day to help keep thyroid hormone levels adequate. TSH tells thyroid cells to produce thyroid hormone.

When your thyroid hormone levels start to fall, the pituitary secretes more TSH to help raise the thyroid hormone levels. The American Association of Clinical Chemists notes that symptoms of hypothyroidism develop when the TSH is higher than 2.5. TSH can rise as high as 500 or so in severe hypothyroidism. Your level is slightly elevated but it's enough to cause symptoms of hypothyroidism such as elevated cholesterol and elevated diastolic (bottom number) blood pressure.

If TSH is elevated and thyroid hormone levels are normal, this is considered subclinical hypothyroidism. You want to look at your FT4 and FT3 levels to see how much available thyroid hormone you have in your blood circulation. Even with subclinical hypothyroidism, treatment with replacement hormone is generally needed. The FT4 and FT3 levels are used to determine the best type and amount of replacement hormone. Best, Elaine

Oct 19, 2009 9:22 AM

Guest :

Hello

I found this page because my blood level is a bit strange. Maybe you can help me.

I am from Denmark therefore the number are a different then yours.

A month ago:
TSH: 1,06 (0,3-4,2)
T3: 1,3 (1,2-2,7)
FT3: 1,2 (1,2-2,7)
T4: 12,8 (13-23)
T4 uptake: 0,92

A couple of days ago:

TSH: 1,12
T3: 1,2
FT3: 1,2
T4: 11,4

My T4 i falling and my T3 is in the low end of normal. But my TSH is normal.

Why is my T3 and T4 low?
Can i have any other blood samples done?
Do i have have hypothyroidism?

I have diffent symptoms as hairloss, pain in my feet and legs.

Thanks Anja

Oct 19, 2009 11:37 AM

Elaine Moore :

Hi Anja,
You're not hypothyroid based on your labs, but your FT4 and FT3 are probably too low for your body's needs. Although TSH isn't elevated you could have thyroid hormone resistance or a central hypothyroidism. I'd ask your doctor about the possibilities and have him run more tests like the TRH. Best, Elaine

Nov 2, 2009 1:34 PM

Elaine Moore :

Hi Anastasia,

If you've been on any meds, including estrogens or progesterone, they can cause a false elevation of the FT3 level. Ideally, all your levels would be within range, but since we have so much less FT3 compared to FT4 I'm not sure your doctor will be concerned about it. If he or she is, he could order an FT3 by dialysis test and this test result would be more accurate as it's not influenced by interfering substances the way the FT3 result is. Best,Elaine

Jan 29, 2010 4:15 PM

Elaine Moore :

Hi,
As soon as your thyroid hormone levels begin to fall, the pituitary gland tries to correct the problem by secreting more TSH. TSH orders thyroid cells to produce more thyroid hormone. When TSH is elevated and thyroid hormone levels are within the normal range, the condition is called subclinical hypothyroidism.
See http://autoimmunedisease.suite101.com/article.cfm/subclinical_hypothyroidis m
for a description of this condition.

Several years ago the TSH range was changed, and today TSH levels higher than 2.5 indicate subclinical hypothyroidism. Even though your thyroid hormone levels are within range, they're probably too low for your body's needs.
And even though you were probably tested for TPO and thyroglobulin antibodies, you probably weren't tested for blocking TSH receptor antibodies. These cause atrophic autoimmune hypothyroidism.

A test for total TSH receptor antibodies or TBII will tell if you have this form of hypothyroidism. You can try getting by without thyroid replacement hormone, but this can lead to other problems, including elevated lipid levels. Best, Elaine

Mar 11, 2010 5:21 PM

Elaine Moore :

Hi,
TSH can be falsely elevated by both TSH antibodies and by heterophile antibodies. Since your FT4 isn't low, your doctor should run a TSH by dialysis test, which removes interfering substances.

Or if he agrees that TSH is likely falsely elevated, he can just monitor your FT4 and also your FT3 levels to ensure that you're on optimal replacement hormone. It's important too to check parathyroid hormone levels and your ionized calcium level since if these levels are off they can cause symptoms similar to those of hyperthyroidism. Best, Elaine

Mar 15, 2010 11:26 AM

Elaine Moore :

HI,
An elevated TSH with normal thyroid hormone levels indicates subclinical hypothyroidism, autoimmunedisease.suite101.com/.../subclinical_hypothyroidism

It means that your thyroid hormone levels are too low for your body's needs and your pituitary is trying to help by secreting more TSH. Usually, thyroid replacement hormone is needed. Best, Elaine

43 Comments

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