Thyroid UK
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Confusing blood test results

Hello, I am new to this site. I am looking at advise as I am rather confused with my thyroid test results and want to make sure my doctor is doing the right thing by not treatment and waiting 2 months and re-testing me. I also should say I am 23 weeks pregnant so not sure if this is an influencer.

My results are: TSH: 0.37 mu/L; T3: 3.8 pmol/L

My doctor just said its boarderline low and not lower enough for treatment. But I have been signed off work, as I am so tired, no appetite, and can easily sleep at any opportunity plus my heart rate keeps spiking over 100 bmp when resting randomly. I really dont want to go through the whole pregnancy like it and definitely not when a new baby is here.

Any advise would be much appreciated.

12 Replies

I'm afraid we need a bit more information. :) Do you have the range for that FT3 result? And do you have an FT4 results and range?

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They never tested my FT4 only FT3.

The FT3 range they gave was 3.5 to 6.5 pmol/L and my reading was 3.8.


So, to which result was your doctor referring when he said 'borderline' low? I hope he didn't mean your TSH, because he would be completely barking up the wrong tree!

You need to ask him to test your FT4 and your antibodies - TPOab - not possible to make any sort of diagnosis without testing those two, because they hold the key. :)


Yes she said it was my TSH and need to monitor it. I am assuming because my result was 0.37 and the range is 0.55 to 4.78.

I am speaking to another doctor on Thursday and I will ask if my FT4 and antibodies could be tested as well.


OK, so perhaps you're wondering what my thinking behind this is? Well, your TSH is low, admittedly, but your doctor seems to be associating that with hyperthyroidism and ignoring the very low FT3. But, if your FT4 is also very low - bottom of the range, or under - then there's no way you can be hyper, you are hypo. And, what your doctor should be considering is Central Hypo, where the problem is with the pituitary (Secondary Hypo) or the hypothalamus (Tertiary Hypo) rather than the thyroid itself.

If this is the case, it's very important that the pituitary should be investigated, because it doesn't just make TSH, it makes a lot of other hormones, as well, and they might be equally low. So, you need to be referred to an endo rapidly.

The problem is, the majority of GPs have never heard of Central Hypo, and just think 'low TSH = hyper' and give the patient the wrong treatment. So, they need to be told about it. They, however, cannot test the other hormones, I don't think, it has to be an endo.

As for the antibodies, that should really be standard testing - it is in other countries. There is just a chance - a slim one - that your TSH is so low because you've just come out of a Hashi's flare, and the TSH hasn't recovered, yet. But, I think the problem is more likely to be the pituitary, I'm afraid.


Welcome to our forum and it is all very strange to us when first it is suggested we may have a problem with our thyroid gland. Particular care is needed if someone is pregnant.

If you are in the UK we are not diagnosed as hypothyroid until the TSH reaches 10. This is high and can also cause clinical symptoms. In other countries, people are diagnosed if TSH is above 3 with clinical symptoms.

What you need is a Full Thyroid Function Test and I doubt GP will do this but we have two private labs which will do all of the ones you need.

All tests for thyroid hormones have to be at the earliest possible, fasting (you can drink water). If you were taking thyroid hormone replacements you'd allow a gap of 24 hours between last dose and test and take afterwards.

The TSH, which most doctors diagnose by is highest early a.m. and drops throughout the day and could mean the difference between being diagnosed or not.

You need TSH, T4, T3, Free T4, Free T3 and thyroid antibodies. If antibodies are present regardless of your TSH being insufficient to be diagnosed, you should be prescribed levothyroxine.

If you have thyroid antibodies in blood you'd have an Autoimmune Disease called Hashimoto's or Hashi's for short.

Blood tests are home pin-prick ones so make sure you are well-hydrated a couple of days before blood draw. The private labs can advise if you don't think you will be able to pin-prick your fingers.

When you post your results you also have to give the ranges. Ranges are in brackets after the results. Labs differ in their machines so the results/ranges may differ.

Your doctor should also test B12, Vit D, iron, ferritin and folate. Deficiencies can also cause symptoms.

Put your results, with the ranges on a new post for comments.

The labs are Medichecks and Blue Horizon.

Always get a print-out of your results with the ranges and post for comments.

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I will certainly pursue this. I already have an autoimmune condition - Coeliac Disease, so maybe its related. My Vitamin D has been constantly low regardless to the supplements I take, so the doctor just monitors that, my Calcium level is low along with albumin level. I also have an abnormal blooding clotting disorder which is has not been named as the consultant is unsure. My inflammatory markers are always high too. In my mind I feel this all has to be linked in someway, 6 years ago I ran the great south run with no training, thought nothing of it, now I struggle with a simple dog walk. So determined to get to the bottom of this so I can at least help myself get back to normal.


We have to find the root cause, if possible, of your inflammatory markers etc. I hope the Specialists are able to do so. Then you can begin a recovery programme. Once we have one autoimmune condition we can develop more but I hope you will soon get a diagnosis.

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I will certainly mention it to the doctor I already have low Vit D which is staying low even though I now take liquid vitamin D, low calcium and low albumin. So will ask for the tests. I just hope this doctor is more switched on to the area.

But you have said does make sense and if the doctor refuses more tests I will get them done privately.


Low calcium can be linked to parathyroid problems. If you have problems with your pituitary it can affect your ability to breastfeed so you need to sort it out before the baby arrives. Definitely try and see an endo, one who doesn't specialise in Diabetes like most of them do.

One cause of fast pulse rate and extreme tiredness is low iron - presumably your doctor has tested this?


That’s interesting you say about breast feeding. With my others I could only get to 2oz’s which is no good so ended up supplementing with bottle. The breastfeeding midwife put it down to me suffering raynards.

My parathyroid was check and was on the lower end of normal and they never checked my Iron so my midwife is arranging that. I have mentioned it to my haematologist team I am under and they are very interested in the findings and getting me in ASAP so they can go through what’s been done so far and no doubts more tests follow but they didn’t understand why my doctor just said a 2 month review and no follow with other relevant tests.


Prolactin is one of they hormones they check when looking at pituitary malfunction. Is is also, as the name implies, involved in lactation ie breastfeeding, so it would seem that your pituitary is not functioning well. This is highly likely to be what is causing your strange thyroid results. You do need to see an endocrinologist who knows his/her stuff because GPs only look at your TSH result, and your TSH result will not accurately represent your thyroid status. The TSH is a hormone produced by the pituitary to tell the thyroid to produce more hormone, so if your pituitary isn't working properly your thyroid will never produce enough hormone. In fact your doctor may conclude that you are hyperthyroid purely on the basis of your low TSH and prescribe anti-thyroid hormone when you need more.

The treatment for your thyroid will be the same as if you were hypothyroid in a 'normal' way - Levothyroxine, but your blood test results will need to be interpreted by someone who knows to ignore the TSH, which today's doctors are told is the 'gold standard', when in fact it is anything but!


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