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Thyroid Low T4, normal TSH & T3 Lab results


I am wondering about my lab results. I started Levothyroxine in October. My T4 is staying low, my TSH decreased, and my T3 is going up. But I still have symptoms, fatigue, aches and pains, weight gain and other smaller symptoms. I have arrhythmia that may be associated with hypothyroidism according to my cardiologist.

Throughout my dosage, I felt some of my symptoms lessen as I hit 50ug levothyroxine, less crashing fatique, less faintness, and less arrhythmia. For two weeks on 50 ug I felt almost completely normal, with no aches, arrhythmia, fatique. But after those glorious 2 weeks my symptoms started coming back (ache, fatigue, arrhythmia) while still on the 50ug dose. I asked my Dr. to up to 62.5 ug levothyroxine, but this dosage has not helped, and I am feeling aches, fatigue and arrhythmia again. I feel that I should be better, my Dr. probably won't increase my levo. dosage with the TSH being under 1. (I didn't ask for t3 uptake, that was my Dr's request).

My Vitamin D is low at about 20 ng/mL, but when I try to raise it past 1000 IU my arrhythmia seems to bother me more.

Any suggestions about where to go from here would be appreciated.  

Here are my lab results, most recent first:

1/27/2017 have been on 62.5 ug levothyroxine for 6 weeks:
TSH 0.56 ulU/ml 0.27-4.20 uIU/mL in range
T4 Free 0.9 ng/dL 0.9-1.8 ng/dL in range 0% of range
T3 Free 3.6 pg/mL 2.4-4.2 pg/mL in range 82% of range
T3 Uptake 31.80% 21.6-34.1 % in range

11/30/2016 have been on 50ug levothyroxine for 6 weeks:
TSH 1.24 uIU/mL 0.27-4.20 uIU/mL in range
T4 Free 0.9 ng/dL 0.9-1.8 ng/dL in range 0% of range
T3 Free 3.1 pg/mL 2.4-4.2 pg/mL in range 39% of range

9/29/16 had been on 25 ug levothyroxine for ~6 weeks
TSH 2.52 uIU/mL 0.27-4.20 uIU/mL in range
T4 Free 0.9 ng/dL 0.9-1.8 ng/dL in range 0% of range
T3 Free 2.9 pg/mL 2.4-4.2 pg/mL in range 28% of range
T3 Uptake 31.6 % 21.6-34.1 % in range

8/10/16 not yet taking levothyroxine
TSH 5.02 uIU/mL 0.27-4.20 uIU/mL high
Free T4 0.8 ng/dL 0.9-1.8 ng/dL low -11% of range (under)
Free T3
T3 Uptake 30.4 % 21.6-34.1 % in range

Thank you!

5 Responses
Avatar universal
Have you ruled out hyperparathyroidism? If not check your serum calcium and PTH together as creating problems when taking Vitamin D seem to be due to hypercalcemia.

Make sure you take levothyroxine on empty stomach and give sufficient time before taking food and other supplements.
Avatar universal

I have had a test for parathyroid last fall, and a calcium test earlier in the year:
4/13/16  calcium 9.6 mg/dL (range 8.5-10.5 mg/dL)
8/10/16   PTH  20 pg/mL  (range 15-65 pg/mL)

Both are in range.

I was more concerned that despite increases of levothyroxine, and a lowering TSH to the low end of the range, my Free T4 remains at 0% of the range, at the bottom value of the range. Shouldn't my Free T4 be increasing? Why would it not increase with increasing dosage of levo.? Should I be concerned, or should I just focus on the Free T3 levels? What would be the optimum Free T3 level or range?

Thank you for your time.
Probably a lab error, try to do the Free T4 and TSH on a different lab. The reason said is because your TSH value is responding correctly to the dose like when you adding more levothyrxine your TSH is coming down and when you stopping TSH is increasing. Anyway never stop medicine as TSH is good marker in most people though exceptions there like in pituitary problems.

I think 50 ug is the correct and safe dose for you based on TSH value.
Hi, just to clarify, do you think the lab made a mistake 3 times in a row? Or do you think that particular lab is performing the test wrong? Thank you!
May be as your TSH value is responding to thyroid hormone pill. If the three lab results of Free T4 are true then need to up the dosage till it comes close to mid range in reference range. For accurate Free T4 results need to make sure levothyrxine is not took prior to blood draw for at least 18 hrs.
But if I up the dosage of levothyroxine, won't my TSH go down further? Would my FT3 then go up further? My FT3 is in the 82% of range on the latest test. Is there a reason to raise the FT4 to midrange if the FT3 is already near the top of the range? Thank you!
I don't take my levo. the morning of the bloodtest, more than 18hrs between.
Avatar universal
A good thyroid doctor will treat a hypothyroid patient clinically by testing and adjusting Free T4 and Free T3 as needed to relieve symptoms without being influenced by resulting TSH levels.  Symptom relief should be all important, not just test results.  I say that about TSH because it is frequently suppressed below range when taking adequate thyroid med.  That does not mean hyperthyroidism, unless you have hyper symptoms due to excessive levels of Free T4 and Free T3.  Your doctor is erroneously medicating you based on achieving a TSH level to his liking.  That does not work for many hypothyroid patients, like yourself.   Many of us have found that we needed Free T4 at the middle of the range, at least, and Free T3 in the upper half of the range, adjusted from there as needed to relieve hypo symptoms.  

In addition, hypo patients are very frequently deficient in Vitamin D, B12 and ferritin.  You need to get those tested and then supplement as needed to optimize.  D should be at least 50, B12 in the upper end of the range, and ferritin should be at least 70.  All are important of you.

The reason your Free T4 has not increased with increasing med dosage is that serum levels of thyroid hormone are the sum of both natural thyroid hormone and thyroid med.  As you start taking thyroid med, TSH drops, and that stimulates less thyroid hormone from the gland.  Only when the dosage is increased enough that TSH is no longer a  significant factor will further med dosage increases start to increase your Free T4 and Free T3 levels.  

If you want to confirm this, read at least the first two pages of this link, and  more if you want to get into the discussion and scientific evidence supporting all that is recommended.  If your doctor continues to treat you based on TSH you may need to give him a copy and ask to be treated clinically, as described.

Avatar universal
Thank you, Gimel, for your response, and link to the pdf. I found the following within that document:

"If the FT4 is below mid-range, then FT3 should be in the upper end of its range, or as needed to assure thyroid
sufficiency (31, 44)."

Note that my FT3 is in the 82% of range on this last test. Most of the treatment recommendation ranges mention FT4  FT3 both in the half or top quarter of the range, but I never see much mention of the FT4 being low and FT3 being high. Since FT3 is the biologically active form of T4, I worry about it being to high. How high is too high for FT3? I don't mind upping my Levothyroxine dose, if I can persuade the endo, but I do worry about too much FT3 as I already have arrhythmia, and increased night sweats.
I'm not sure how you calculated your FT3 percentage, but I calculate it at 67% rather than 82%...

Avatar universal
I expect that the reason your FT3 is higher in range than FT3 is that your body is converting more T4, in an effort to maintain thyroid function as well as possible.  So increasing your T4 dosage should not affect FT3 the same amount.

Also, don't be concerned about your TSH.  IF you have any reservations about a suppressed TSH, have a look at Rec. 10, on page 13 of the link above.
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