Thyroid Disorders Community
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5708149 tn?1372878122

How accurate are lab tests?

I am a 20 year old female. Two weeks ago, I finally told my mom I wanted to get some tests done. I haven't felt like myself for a while. A year ago, I went through some anxiety/depression but have since been off the meds for quite a few months. My memory within the last year or so has been really bad. Recently, I woke up one morning and could not remember who I was for several minutes. I have gained weight within the last year (my sophomore year of college) and have always felt tired during the day. I would much rather sleep all day than do anything else. My appetite has been increased, I have seemed to be more irritable, and I am always hot. The machine was down at the lab, so I did not get all my results that day, but all of my results: red blood cell count, iron, B12, blood pressure, was all normal. I found out about a week later that the results had shown a TSH of 6.9, which they said was high so they put me on Synthroid for hypothyroidism. That day, before I started the medicine, they did another TSH test and tested my t4 (but not my t3?). I called them and basically pestered them for my results (this was about a week or more later than the first test). The nurse finally called me back and told me my TSH level was normal (after no meds) and that my t4 was low (she didn't give me the actual numbers). My mom remembered I got blood work done last year, and got them to check what my tsh was last year (maybe it was high then, and they never told me). She once again gave no numbers but said it was normal. I know my grandmother and her sister both have thyroid problems (her sister had a goiter(s) removed). My questions: could the blood that gave the high tsh have rendered wrong results since they tested it a day or two later, could the machine not be accurate, could the abnormal TSH test be abnormal because I was going to start my period that week? They are now sending off my most recent blood (with the normal TSH) off to another lab to be tested, but if it is normal, what does that tell me? Out of the past year, one of three showed me to be hypothyroid, but the others were normal. What is your take on this? If I wanted to go to another doctor for a blood test, how long do I have to be off the Synthroid to get an accurate reading not affected by the medicine? Should I even keep taking the Synthroid since I don't even know that I have hypothyroidism? Thank you for any answers or advice. Our heads are swimming right now.
15 Responses
649848 tn?1534637300
First off, TSH is variable and can fluctuate greatly, even within a day's time; it's totally inadequate to diagnose/treat a thyroid condition, in spite of the fact that it's considered the "gold standard" for thyroid testing.  

You need to have Free T3 and Free T4 (make sure you specify FREE or you will get total, which is not the same test), in order to know what's going on.  Your doctor is required, by law, to provide you with copies of your lab results, free of charge.

If you can get a copy, please post the actual results here, along with reference ranges that vary lab to lab and have to be posted with results.

I'd also like to see the results of your B-12 test.  Even though it might have been in range, it might not have been high enough for you.  Many doctors think that results "in range" are good enough, and that's just not true - that goes for thyroid, as well.

You should get in the habit of getting copies of all blood work and other lab tests and keep a copy for your records, note medications and symptoms on each lab report.  That will become your running record, that you can always look back and see where you felt best/worst.

Have you been tested for thyroid antibodies to determine whether or not you have thyroid antibodies, which would result in a diagnosis of Hashimoto's Thyroiditis.  Hashimoto's is the number 1 cause of hypothyroidism in the developed world.

Have you had an ultra sound to determine whether or not you have nodules on your thyroid?  Nodules are very common and usually nothing to worry about, but it's nice to know if you have them.

"I know my grandmother and her sister both have thyroid problems (her sister had a goiter(s) removed)."  Can you please explain this?  A goiter is simply a swollen thyroid and you only have one thyroid that consists of 2 lobes and an isthmus.  Did she have her thyroid removed?

We can't tell you whether or not to continue with the Synthroid.  If you decide to go to another doctor, you don't have to go off the Synthroid, first.  If your labs come back good, and you feel good, that would indicate the Synthroid is helping.

What, if any, symptoms do you currently have?  Has the Synthroid done anything to alleviate symptoms you previously had?
5708149 tn?1372878122
Thank you SO much for being so helpful in your reply! I am so new to blood tests and this site. This doctor's office never calls me like they say they will, and even when I call and ask my results, I am lucky if they call back that day. Today, after waiting 7 hours, I pestered them again just enough to get her to send off the rest of my blood and to tell me my t4 was low and my TSH was normal. I asked about t3, and she said they didn't test that. We had to basically force them to even test my thyroid with my first blood test.

Because of all of that, I doubt what they tested was the free t4, and I know they didn't test the free t3. Unlike my mom's doctor, which is so nice to post all her tests online for her, they don't tell me any numbers, nor do they give me any of the paperwork. I will try to get them to mail it to me or have it at the font desk for me if I can make someone get on it. I did not even know about the antibodies testing until today, so they haven't tested that at all.

At this point, my best bet may be to go to a new doctor. I have never had an unltrasound, and I just learned of the history of thyroid conditions on my dad's side today from my grandmother who probably does not really understand what a goiter is, which I didn't either, so I guess throw my lack of knowledge and goiters out of that post of mine.

So, if I had another doctor test me while I am on Synthroid and the results are good, it is from the Synthroid for sure or could it still have been my natural levels? I have currently not been on the Synthroid long enough for me to even tell anything (only one week), but my mom thinks I should stop taking it.

I just want to know why I am always hot, tired, forgetful, and started gaining weight just within the past year or so and even worse within the last few months. :/ I wish there was a blood test that could just test everything because I know my symptoms are pretty generic.

Should I request my other blood test and last year's blood test results if they have them?
649848 tn?1534637300
Synthroid has a long 1/2 life so it takes a while to get out of your system, but it also takes a while (4-6 weeks) to build to maximum potential in your blood when you first start taking it.  If you've only been on it a week, it won't have built much in your blood, so you could, either go ahead and have another blood test now, before it builds anymore, or simply stop taking it for a few days, then get another test.  

You said the nurse told you your T4 was low........  with  a higher than normal TSH, low T4, even if it was total, not free, indicates that you are hypo and really do need the medication.  

Thyroid 101......... Your thyroid produces the hormones T4 and T3, but mostly T4 and very little T3.  The cells don't use T4 directly; it has to be converted to T3. The pituitary constantly monitors for adequate levels of T3 and T4.  If it senses that levels are low, it puts out Thyroid Stimulating Hormone (TSH) to stimulate the thyroid into producing more hormones. If the thyroid doesn't respond, the pituitary continues to crank out more and more TSH.  The lower thyroid hormone levels (T3 and T4) go, the higher TSH will go.

Of the T4 produced by the thyroid, some of it will be attached to a protein.  The T4 attached to the protein is not available for conversion.  The only T4 that can be converted is FREE T4, which is that portion not attached to the protein.  When Total T4 is tested, the result contains both the amount attached to protein and the amount that free....... since the free is what's available for conversion, that's the main thing we need to know.

T3 works the same way........ a portion is attached to a protein and that portion is not usable by the individual cells.  The usable portion is the FREE T3, which is the portion not attached to protein. Again, testing Total T3 includes both bound and unbound T3; we're concerned, mostly, with the unbound, because that's what's available for our cells to use.

With Hashimoto's, the body sees the thyroid as foreign and produces antibodies to destroy it.  Many of us here, on the forum, have Hashimoto's.  The destruction process can take years, but as the antibodies destroy healthy thyroid tissue, the thyroid makes less and less hormones, until eventually, it produces nothing and the patient is totally dependent on the replacement hormones - some of us are at that point.  Along the way, replacement hormones have to be adjusted periodically, to account for the decreased thyroid hormone production.  

The antibody tests you need to diagnose Hashi's are Thyroid Peroxidase Antibodies (TPOab) and Thyroglobulin Antibodies (TGab). You need them both, because some of us have one or the other, some have both, so not testing them both, could result in misdiagnosis.  While Hashimoto's is most often associated with hypo, early stages can be characterized by periods of hyper alternating with hypo. Symptoms of hyper and  hypo can "overlap", such as the tired, forgetful.  

Being hot is often a hyper symptom, so you could have Thyroid Stimulating Immunoglobulin (TSI), which is the definitive test for Graves, though, it's probably an unnecessary expense, since your high TSH and low T4 would pretty much rule that out.

In my opinion, it's always worth the effort to get copies of previous labs, but that's up to you. Our labs are our "medical history", that show where we've been.  Mine have become a running record of my disease, because I note on each one, the medication(s)/dosage(s) I was on at the time of the blood draw and what, if any, symptoms I was experiencing.  That lets me know what levels I need to target.

You DO need a different doctor asap........Is there any way you can go to your mother's doctor?  Sounds like you might have better luck, there, getting tests you need.  But then if she doesn't have a thyroid condition, it's hard to say, because many doctors are reluctant/refuse to test both FT levels, since they're taught that TSH is the "be all, end all" of thyroid treatment.

It's best to call a potential doctor and ask questions, often via a nurse or office manager, about how that doctor tests/treats thyroid patients. Questions should be  1) what tests are routinely ordered (should be TSH, FT3 and FT4 - antibodies, typically, only need to be done once).  2) Is the doctor willing to prescribe medication with both T4 and T3, as needed, including desiccated?  Answer should be yes.. 3) Is the doctor willing to treat by symptoms, rather than simply looking at labs and saying "anything in range" is good enough. For many of us, that's not true.

With your symptoms, I'd also like to see a current B-12 result, so you should try to get that retested.

You should also ask for cholesterol testing, since high cholesterol and hypothyroidism go hand in hand.

5708149 tn?1372878122
Goodness me you are so helpful! So you know all of this stuff from previous experiences and such? That really helps give me a better understanding of what the 'free' means and what t4 and t3 kind of do.

I just got back from the doctor's office. Apparently, it was FT4 they tested but for some reason they do not test T3 at all. I have a lab from a little over a year ago that has CMP, TSH, FT4, CBC, Gran#, Lymph #, Mono#, Gran%, Mono%, Lymph%.

I also have the one from 6/18/13 which has B12, UACOMP (Urinalysis?), CBC, CMP, TSH, and a paper with CO2, NA, Calcium, etc.

Lastly, I have my FT4 and TSH as of 6/26/13.

I cannot begin to thank you for giving me helpful insight on what these things mean. We are talking about trying to find another doctor who seems to be better at this stuff. Please tell me what of an of these things, would be helpful. Also, is there any way to make things like that private? My mom doesn't like the idea of the whole world seeing lab results. Thank you!
649848 tn?1534637300
Please post the TSH and FT4 results from 6/26/13, as well as the ones from last year.  Be sure to include reference ranges, as they vary lab to lab and have to be posted with labs.  Not surprised they didn't do any T3, many doctors don't and if they do, they order total T3, which is not nearly as useful as Free T3.

Also post the B12 result from 6/18/13.

Do you see anything listed for either iron or ferritin, as well as anything to do with cholesterol? If so, please post those, as well.  

Again,  please be sure to post all reference ranges from your lab reports.
5708149 tn?1372878122
2012 TSH:  1.120 mIU/mL  |   Expected: 0.340 - 4.820
6/26/2013 TSH:  2.950 mIU/mL   |   Expected: 0.340 - 4.820

2012 FT4:  0.60 ng/dL   |    Expected:  0.59 - 1.17
6/26/2013 FT4:  0.58 ng/dL   |   Expected:   0.59 - 1.17

6/18/13 (typed it exactly because it was confusing)
Test Name:                   In Range:            Reference Range:               Lab:
Vitamin B12/Folate,                                                                          AT
Serum Panel
Vitamin B12                  458                    200 - 1100 pg/mL
Folate, Serum               >24.0                 Reference Range
                                                             Low:                  5.4

There weren't Reference Ranges on the TSH or FT4, only the 'Expected', which may be the same thing. As for the cholesterol and iron, I am almost certain those were of the things they said were 'normal', but I cannot find either of them on my lab work unless they are listed in some weird 3-letter name, so I guess the few things I provided don't say much. :/
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