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Interpreting TSH and T3/T4 tests

Recently I saw an endocrinologist to check on my thyroid. I have many hypothyroid symptoms (tired, irritable, feeling VERY cold all the time, muscle aches, and before I took birth control my periods were irregular and made me extra shaky and dizzy).

My TSH and T4 results I am determined to argue. I can't see the doctor for two weeks, so I thought I'd get an opinion here.

TSH: 1.50 (normal range .34 - 4.82 ulU/ml)
Free T3: 3.0 (normal range 2.3 - 4.2 pg/ml)
Free T4: 0.60 (normal range 0.59 - 1.61 ng/dl)

The T3 kind of throws me off because it's fairly middle range while TSH and T4 and distinctly lower range. Normal range is determined my a large number of people, and while low normal is healthy for some, another may need to be at a high normal. TSH and T4 particularly concern me because 1) birth control can make T4 levels look higher than they are and 2) different ranges are used by different clinics. By this I determine I can argue that I may have hypothyroidism and should be allowed to try a drug to help that.

So my questions:

How do you interpret these results? and
Can a general practitioner prescribe a thyroid drug? (I didn't like the endo's attitude, it might be harder to convince him to let me try treatment.)
5 Responses
Avatar universal
Your FT4 level is very low.  Many people still have hypo symptoms until FT4 is right around midrange.  TSH is a pituitary hormone, so it's the least important of the three standard thyroid tests.  While it's "in range", I find it on the low side considering how low your FT4 is.  Low TSH with low FT4 can indicate secondary or central hypothyroidism, which is actually a pituitary dysfunction.  The pituitary doesn't put out enough TSH to stimulate the thyroid to produce T4.

Your FT3 is 37% of range, but once again, many people will keep their hypo symptoms until FT3 is in the upper half to upper third of range.  

If you're taking birth control pills, you should request FT4 by direct dialysis, rather than immunoassay.  Direct dialysis gives an accurate reading despite taking BC.

You have to use the range used by your own lab.  Different labs have different ranges depending on a lot of things, but partly their methodology and the test kits they buy.  

I think you're a prime candidate for thyroid meds, based on both your FT4 and symptoms.  Any doctor can prescribe thyroid meds.  Be prepared, though; many doctors look at TSH and nothing else (even when they order FT3 and FT4, all they're really concerned with is TSH).  If your doctor balks at meds, you might ask him to order TPOab and TGab.  They're the two antibodies associated with Hashi's, which is the most prevalent cause of hypo in the developed world.  If either of those were elevated, he might be more easily persuaded to start meds.
Avatar universal
That's what my research in the last few hours has yielded. The TSH number confuses me since it's not high, but I am more interested in trying a medication and see if it works. Although I wouldn't mind an official diagnosis, after 5 years of bouncing from doctor to doctor (well, I had a doctor hiatus of two years when I tried to improve by myself trying lifestyle and other nonmedication options. I tolerate drugs as well as I tolerate food, and that's not a good thing.)

Do you suppose a general practitioner know the type of thyroid drugs and dosages to try? My GP is reasonable and much easier to meet with than the endo doc--assuming I/my GP decide not to get more tests done.
Avatar universal
Low TSH with low FT4 can indicate secondary hypothyroidism.  It's when your pituitary doesn't put out enough TSH to stimulate your thyroid to produce hormone.

I don't tolerate meds well at all, either.

It really depends on the PCP.  Some will only prescribe T4 meds (like Synthroid and generics), some will know how to use T3 along with the T4, and some understand desiccated.  Most often, we are started on T4, so any PCP should be familiar with that.  

Just bear in mind that the usual starting dose is somewhere around 25 mcg (especially if you don't tolerate meds well in general).  You take that for 4-5 weeks and retest to see where your levels have gotten to, re-evaluate symptoms and adjust as necessary, and you keep repeating that until symptoms are relieved.  There is no way to rush this.  If you take too much or increase too fast, you could have hyper-like symptoms, which are even less pleasant (in my opinion) than hypo symptoms.

I hope your PCP will be able to focus on your FT4, which is on the floor of the range, and ignore TSH.  You might have to pound that home a bit...
Avatar universal
I have an appointment with my gp later this week, but I recently had a second appointment with the endocrinologist.

I made logical arguments based my research for why I think I should have more tests for my thyroid, but my endo was a broken record saying "your TSH is normal. You don't have hypothyroidism." So, clearly I know what kind of endo he is.

I did make him run Tg and TPO tests.

My TPO was .5 and "normal" is referred to as <9
My Tg was <20 and "normal" is referred to as <116

At first I thought, "Well, not Hashi's, so probably a different underlying issue." But when I read up on this, it sounds like Hashi does not necessarily have to be super high antibodies, and a lot of articles refer to antibody tests as positive or negative.

I'd appreciate any input.

Will have to discuss/argue with the gp next!

Thanks in advance.
Avatar universal
Both of those are negative.  Hashi's does not have to be super high antibodies, but you do have to be above reference range to confirm it.  Both TPOab and TGab can be "somewhat" (a term that usually goes undefined) elevated with other autoimmune diseases as well.  Your TPOab is extremely low, and your TGab could be zero since all we have is "less-than 20", not an actual number.

Just to give you some perspective, my TPOab on diagnosis was 900+, and my TGab was 3,000+.  These are not unusual values.  Your antibody tests don't indicate Hashi's.

Your FT4 is extremely low in range.  However, FT3, which usually correlates best with symptoms, is still at a fairly decent 37% of range.  That could be what's keeping your TSH fairly low at the moment.  When I say fairly low, I mean that your FT4 is so low that most people with that FT4 would have much higher TSH.  

Good luck with your GP.
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