How reliable is the thyroid test?

May 11, 2009 5:58 PM

My thyroid test came back normal, but I have a bunch of symptoms that seem like hypothyroidism. How reliable is the test?

Symptoms that make me question the results:
- many years: dysthymia (anxious, down, irritable)
- many years: low heart rate (resting pulse at doctor's office: 48)
- recent: elevated blood pressure
- past year or so: can't seem to lose weight despite reducing calories and exercising.

posted by The Dutchman to health & fitness (27 comments total)

I'll be watching this because I have similar things and my MD told me it was all psychological. I don't believe it, though I do believe stress makes it worse.
posted by small_ruminant at 6:00 PM on May 11

There isn't just one test-- which test(s) did you take, and what were the numerical values returned?
posted by availablelight at 6:09 PM on May 11

Doctors have been telling me for years that my thyroid chems are normal, but I have nearly all of the symptoms of hypothyroidism as well. No doctor has ever seemed concerned. Even with a pulse rate and low enough blood pressure that Ive had nurses ask me if I was dead.

Its been my experience when you ask "Well, what were my numbers" most doctors don't want to tell you, nor what test it is they ran exactly.
posted by strixus at 6:22 PM on May 11

Strixus, you can request a copy of the lab report and see the numbers for yourself, plus the test type.
posted by 6:1 at 6:25 PM on May 11

I'll call and ask tomorrow what the test was and my numbers, and will post here.
posted by The Dutchman at 6:31 PM on May 11

A thyroid test is pretty reliable, but it depends on what they tested. The basic one is just a TSH -- thyroid stimulating hormone. That SHOULD be out of whack when you are hypothyroid, but it's conceivable that it could be normal despite hypothyroidism or hyperthyroidism. If you're suspicious of thyroid problems, you can check T3 and T4, the actual thyroid hormones.

More broadly, I think you should go to your physician and frankly talk about how your dysthymia is a problem. If your physician isn't responsive, you should find someone else who WILL address the problem. A physician can easily enough say "your thyroid is normal," but if they don't pursue OTHER things, they've done you no good. If the one test is negative, it's time for your physician to address your problems and consider other causes, and thus, solutions.
posted by davidnc at 6:39 PM on May 11 [1 favorite has favorites]

As it happens, I'm sitting here studying (or screwing around on Metafilter instead of studying) the thyroid disorders component of clinical endocrinology. There appear to be two primary blood tests done to diagnose hypothyroidism, and they're both simple, sensitive and reliable. Here's what my course notes have to say on the subject:

Diagnosis of Hypothyroidism
Determinations of both the serum FT4 and serum TSH concentrations are warranted in patients who have a clinical syndrome that suggests hypothyroidism. Serum measurements of T3 are not helpful in the diagnosis and may be normal in hypothyroid patients.

The concomitant finding of a decrease in serum FT4 and increase in serum TSH levels confirms the diagnosis of hypothyroidism caused by thyroid gland failure; an increase in the concentration of serum TSH together with a normal or low normal serum FT4 indicates that the patient may be at an early stage in the development of primary hypothyroidism (subclinical hypothyroidism).

Basically, your level of serum FT4 is a direct reflection of how well your thyroid is functioning, since T4 is the major circulating hormone produced by your thyroid's cells. Measuring levels of serum TSH (thyroid-stimulating hormone) is a more indirect and also more sensitive way to test thyroid function -- TSH is a circulating hormone that stimulates your thyroid to produce thyroid hormone, and more of it is produced when circulating thyroid hormone levels are lower than they should be.

Disclaimer: IANAD.
posted by killdevil at 6:44 PM on May 11

Go to an endocrinologist. Most doctors still consider a TSH of up to 5 to be normal. That is too high; the numbers have been revised downward. I feel best when my TSH is less than 1.
posted by jgirl at 6:58 PM on May 11 [1 favorite has favorites]

As a general matter, you're likely to get better results from doctors if you 1) find one who will take your symptoms and complaints seriously, and 2) don't self diagnose. Not only are you unlikely to have as good an idea as a trained physician as to what the hell is going on, but you're also likely to interfere with proper diagnosis by doing it yourself. Going to your doctor and saying "I have all these symptoms, it must be hypothyroidism, and you should treat me," and then having a thyroid test come up normal, isn't likely to get you anywhere. But saying "I have all of these symptoms, please find out what's wrong," will, with a good physician anyways, get you a lot farther.

So if your current doctor isn't doing anything for you, you might consider finding one who will, but don't try to guide the doctor's diagnosis. That's almost always counterproductive.
posted by valkyryn at 7:02 PM on May 11 [1 favorite has favorites]

The TSH test is pretty reliable. The problem is that there's some controversy over where in the range of readings to place the "above normal" marker that would result in a hypothyroidism diagnosis.

Previously, anything between 0.5 and 5.0 was considered normal, with lower numbers indicating hyperthyroid and higher numbers indicating hypothyroid. However, because so many patients inside of the normal range are experiencing symptoms that abate when they are treated, the American Association of Clinical Endocrinologists has recommended that the normal range be revised to 0.3-3.0.

If your number is above 3.0 and you are experiencing symptoms, find a doctor who takes that seriously.
posted by decathecting at 7:06 PM on May 11

First: agreeing with those above that say many GPs tend to read TSH results as normal when they are not. After my thyroid was removed I was on a dose of .175 mg and my GP thought my TSH was good; my endocrinologist took one look at my TSH and raised my dose to .200 mg. I suspect it's still a little too low, but at least I can get out of bed. My endo has given me specific instructions to only get my blood tested at one particular clinic, because most clinics don't do the free T4s test, and it's critical. While I adore and trust my GP, it seems that thyroid issues are really best left to the specialists.

Second: I'd advise you to stop fixating on thyroid issues. You're not reporting the key symptoms of hypothyroidism, which are tiredness and low body temperature. Those are really prominent, common and annoying symptoms of hypothyroidism. While some people don't experience these as much as others (I know of someone who ran a marathon after having no thyroid hormone in her body for a month, which is INCONCEIVABLE to the rest of us). But the vast (vast) majority of people who suffer from hypothyroidism will notice the tiredness and coldness first. Be open to other explanations for your symptoms.

You have to be your own advocate when it comes to your health. Pursue more testing, but don't get your head locked in a diagnosis that might not be yours.
posted by Hildegarde at 7:31 PM on May 11

Yeah, definitely go to an endocrinologist and tell that doctor that you suspect you are subclinical hypothyroid. I did, the doctor took me seriously, I took meds, I felt better within two months.

My TSH was 4.3. Normal, but unbearable based on my symptoms, and I went past my regular doctor's suggestion to "try therapy and Weight Watchers" and found a specialist.

My TSH is now in the 1.3-1.5 range and I feel awesome. Also, I had elevated cholesterol, which was another indicator of being subclinical (TS3 and TS4 levels were really high/low, that sort of thing).

Google "subclinical hypothyroidism" and you will get lots of book results, medical studies, etc. that may help you understand better what to ask/test for and how to talk to the endocrinologist.
posted by Unicorn on the cob at 8:28 PM on May 11 [2 favorites has favorites]

My story is almost the opposite, but the questions are similar: what is going on and can I (and my dr.) trust the results? I've concluded that symptoms don't always correspond with lab results and it isn't always clear what kind of treatment, if any, is warranted. Sorry, as I don't think that's what you wanted to hear.

My employer provides annual health screening which includes a TSH test and 2 years ago, my TSH was 45! Not 4.5, but 45 - over 9 times the upper limit of normal. As it happens, I'm a lab tech and work in the lab that did the testing so, with my Pathologist boss's permission, I had my blood redrawn and retested right there on the spot. Same result. Further testing was ordered, including a FT4, T3, and anti-thyroid antibodies. The FT4 and T3 were below normal and the antibodies were off-the-scale high. All of these results were diagnostic of Hashimoto's hypothyroidism. I was completely shocked.

Thing was, I felt perfectly normal and still do - no fatigue or weight gain, no hair falling out, constipation, etc. Yes, my core temp was/is lower than normal, but I've always been cold sensitive. I'm extremely active and at 5'5" weigh 106 lbs. I went to an endocrinologist who was baffled and left it up to me as to whether to be put on meds or not. (?!) I opted not to take meds. After 2 years of monitoring my lab levels every 6 months, the TSH has slowly dropped to 10 (still abnormal but much better), while the other values have stayed the same. Go figure. I still weigh the same and am as active as ever, working full-time and exercising (power walking, biking, etc.) daily with no obvious feelings of fatigue.

So, to answer your question of how reliable the test is - I wouldn't doubt the lab results (although repeating the test is never a bad idea when symptoms don't match). Thyroid testing in general is quite reliable. But just because the results are normal, after my experience, I wouldn't give up trying to find out what is going on. And, listen to the posters who mention subclinical hypothyroidism as a possibility. You know your body best.

Find a doc who will listen to you and be willing to retest your thyroid as well as test other things such as heart, kidney, diabetes, autoimmune, etc. Good luck and hope you get to the bottom of it and begin feeling better soon.
posted by ourroute at 8:43 PM on May 11

My experience has been that GP's are very conservative when it comes to diagnosing hypothyroidism through blood work. If that is what you have. Simple fact is that it is becoming more and more prevalent. I suffered from a laundry list of symptoms for over 2 years before I was diagnosed with Hashimoto's. Individually each one seemed minor but the sum of 10 or so symptoms equaled a quality of life below 50%. Doc's tried to pass off anti-depressants on every visit and always told me to "diet and exercise". Although I was feeling extremely low, I was not depressed about life in general, I was uber frustrated about my ailing health and lack of interest by my doctors. My blood work always came back normal. FYI I never felt cold. Only after a throat sonogram, which confirmed an enlarged thyroid and nodules, did I get a referral to see an endocrinologist.

Try to take control & keep an open mind. A very happy committed 8 year relationship ended due to my unpleasantness to be around.
- dysthymia (bitchiness, moodiness, depression)
- extreme fatigue (it took all the energy in the world to get out of bed in the morning)
- painful joints (felt like I was 70 yrs old)
- major brain fog
- no libido
- dry mouth (cracked lips)
- insomnia
- weight gain
- constipation
- hair loss
- very dry skin

(Un)Funny thing is, my allergist, during a routine examination about 6 months prior to the disease onset suggested checking my thyroid as he thought it felt enlarged. I told my GP on a routine physical but he immediately dismissed it & so did I.
Also, I would have tried alternative treatments (homeopathy/herbs) first as opposed to synthroid had I known what I know now. And finally, in hindsight, I am pretty confident that a series of VERY stressful events triggered the illness. After all Thyroid Stimulating Hormone is initially released from the pituitary gland, in the brain. So in my opinion stress management is key.
posted by sequin at 8:44 PM on May 11

When I complained about general symptoms of depression, a thyroid test was my doctor's first step. Mine came back normal, and that was the end of that--but not the end of my problems, although we proceeded as though it was standard garden-variety depression with little success.

But recently a friend mentioned having been in the same situation, and having superceded her primary care doctor and gone to an endocrinologist, and her treatment has been very successful.

I am planning to do this myself (you know, when I can get my shit together enough to make it happen), and I see no reason not to recommend that you do so if your medical coverage allows you to. There is no reason to feel shitty if you have the means to help yourself feel better.
posted by padraigin at 9:30 PM on May 11

As a general matter, you're likely to get better results from doctors if you 1) find one who will take your symptoms and complaints seriously, and 2) don't self diagnose. Not only are you unlikely to have as good an idea as a trained physician as to what the hell is going on, but you're also likely to interfere with proper diagnosis by doing it yourself. Going to your doctor and saying "I have all these symptoms, it must be hypothyroidism, and you should treat me," and then having a thyroid test come up normal, isn't likely to get you anywhere. But saying "I have all of these symptoms, please find out what's wrong," will, with a good physician anyways, get you a lot farther.

valkyryn makes very good points. Describe you symptoms, don't self-diagnose. Let the doctor with experience, training and expertise diagnose and figure out where to go next.

Thyroid problems seem to be either very common or very popular topics of discussion these days. The latter means one might overlook an alternative, equally plausible illness with similar symptoms. A doctor won't, or shouldn't, overlook lesser-known alternatives to thyroid problems.

If you don't trust or communicate well with your doctor, find another one. That said, even if you go that route, the advice above still holds.
posted by vincele at 12:08 AM on May 12

I have my thyroid function done regularly for medication I'm on. They should measure two things; TSH, which is how much your body is kicking the thyroid to make it go, and thyroxine (T4), which is actually how much it's working. Together yes, they are good measures of thyroid function.

- recent: elevated blood pressure
- past year or so: can't seem to lose weight despite reducing calories and exercising.
How old are you? Those can be 'normal' for aging; as much as 25% of the population over middle age have high blood pressure.

How thoroughly has your slow heart rate been investigated? Because a really slow heart rate can cause the tiredness and irritability you're talking about; higher blood pressure may be a compensatory mechanism for how slowly your heart is beating. Yes, slow heart rate can be caused by hypothyroidism, but it might also be the cause of your problems, rather than a symptom of them.
posted by Coobeastie at 1:37 AM on May 12

Also, meant to say, what vincele said. I can think of three or four possible different diagnoses for you and I'm only a medical student; going in and bashing the doctor with "It's hypothyroidism and I won't hear different", when it might well not be - not helpful.
posted by Coobeastie at 1:39 AM on May 12

Go to An endocrinologyst. You could have a lump or something on your thyroid that doesnt effect your levels all the time.

Maybe its not a thyroid problem? could it be an adrenal gland problem?

There are other things that could cause that , not just the thyroid.

PS i had m ythyroid taken out about 4 years ago so if you need any more info let me know.
posted by majortom1981 at 5:01 AM on May 12

The TSH test does not work for those of us who have underachiever pituitary glands. I was horribly ill with hypothyroidism when my TSH was 2.3. The only reason I was diagnosed was because my thyroid eye disease made it obvious that I had anti-thyroid antibodies, so I went to a specialist, who used a TRH stimulation test to make the diagnosis.

My endocrinologist pays little attention to my TSH tests, because I do much better if she keeps my free T3 and free T4 in the middle of their normal ranges, and my TSH down at the very bottom of the supposed normal range.

That said, you don't sound particularly hypothyroid. As others have said, there may be a different explanation for your problem. Keep searching. Always find out what your actual numbers are for each of your blood tests—make sure you get free T3 and free T4 levels, not just TSH—and keep them safe. A year later, get the tests repeated and compare your numbers; if your TSH has increased, or the others have decreased, it's worth looking into, even if they are still in the "normal" range.
posted by Ery at 6:06 AM on May 12

Last year, around this time, I had similar symptoms, although the most pronounced were fatigue, generalized anxiety, and weight gain. I also noticed a large lump in my neck. My doctor ran my T3, T4, and TSH levels, and they were all in the normal range. But it turned out I had thyroid cancer. Now that I am on the other side of it, it was only once my TSH got below 2 that I started feeling normal again.

I really think that if I hadn't had an actual lump, that my symptoms would have been dismissed, even though I clearly had a thyroid problem. So yes, I agree with the other that say you should go see an endocrinologist.
posted by kimdog at 6:39 AM on May 12

You may want to take a look at the recommended labwork here

If the problem does turn out to be thyroid or throid/pituitary/adrenal. there's a wealth of useful information on that site.
posted by vers at 7:18 AM on May 12 [3 favorites has favorites]

"See an endocrinologist" x100.

And no, don't say "I think I have hypothyroidism" to the endo. Say "Here are these symptoms which I have, and I want to rule out an endocrinological issue."
posted by Sidhedevil at 9:03 AM on May 12 [1 favorite has favorites]

Following up, just spoke to doctor...
TSH: 4.5
T3 and T4 levels normal.

Doc says that the T3/T4 levels being normal means everything is fine.

I'm not sure exactly what my next step will be, but your responses have been really helpful so far giving me some options.

Oh, someone asked how old I am: 34.

Also, my "normal" temperature has always been 97.6 (my dad's, too). Does this qualify as low body temperature?
posted by The Dutchman at 11:35 AM on May 12

Also, my "normal" temperature has always been 97.6 (my dad's, too). Does this qualify as low body temperature?

I don't think that's low enough to be considered "persistent hypothermia," no. Mr. Google might help, but IIRC persistent hypothermia is more like a constant body temp of 97.0 or below.
posted by Sidhedevil at 11:55 AM on May 12

One more thing: My vitamin D level was 26, and the doctor said it should be 50. He told me to take 1000 units of D3 daily. Not sure if that's relevant to this discussion in any way, but thought I'd put it out there.
posted by The Dutchman at 12:05 PM on May 12

Vitamin D level is relevant to your symptoms. At my nutritonist/endo's office (they share), they've started automatically recommending D supplements within the last year, since so many people are deficient. We spend more time inside and out of the sun.
posted by jgirl at 3:25 PM on May 12