Thyroid UK

Does an 'in range' full blood count result prove my iron, ferritin and B12 levels are fine?

My gp refuses to send me for separate iron,ferritin or B12 level tests saying my full blood count was fine. He's prescribed me anti depressants for tiredness and foggy head which I don't want to start until I've ruled out everything else as to why my TSH levels have improved on 100 thyroxine but still feel unwell. Am I being unreasonable asking for these separate tests. Anyone had them done privately?

9 Replies

Ask your surgery for a print-out of the blood tests you had done by the surgery which should include the ranges and post on another question. I hope it also includes your thyroid function too.

It is not the amount of thyroxine you take that is important, it is how you feel and if still unwell, an increase may be in order. Some GP's think it o.k. to keep us within 'normal range' but this often doesn't make us feel better.


Your GP is wrong on this occasion, unfortunately a full blood count is not sufficient. However, I think their hands are sometimes tied because labs won't allow the other tests to be done if the FBC is normal. The main thing they look for is anaemia, but this is usually a late stage of deficiency. In fact, in the case of B12/folate deficiency, neuro symptoms are often present in the absence of anaemia. The second problem is the MCV. This is below range in the case of iron deficiency, and above range in the case of B12/folate deficiency. So if you are deficient in all 3, then the MCV will appear to be normal.

The next problem comes if you actually manage to get the other tests done (B12, folate, ferritin), because you can test normal for all these things and still be deficient. The joys of lab ranges. I can only speak from my own experience, and say that I was at my most ill when all my blood tests were normal, including thyroid. The only thing I was just below range on was folate. In correcting these deficiencies I am by and large very well, with no change in thyroid medication (I am on Carbimazole).

As Shaws says, it is definitely worth posting all your lab results up in a new question, including thyroid and FBC, because even when they are normal they can give you clues as to the things that might not be optimal. You might just need a tweak in thyroid meds.

It is very disappointing to see yet another prescription for anti-D's when other options haven't been fully explored.


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Totally agree. Also, and I'm speaking from personal experience, by the time something appears wrong in your full blood count, you are in the late stages of deficiency. I have some neurological damage that I now fear is permanent. I had a high MCV for years that was 'not a problem' according my GP because I wasn't anaemic and that's what matters (!!!!!) I was referred to a neurologist about the tingling, nerve pain, loss of sensation and weakening grip in my hand and loss of sensation/nerve pain in my feet. They couldn't find out what was causing it.

Since finding this site, I realised my high MCV was probably a B12 problem. I started supplementing with a B vitamin complex and a separate high dose B12 supplement and noticed a big improvement. I have some permanent loss of sensation in my toes but my fingers are much better. My vertigo has also mostly gone, but rears its ugly head if I forget my B12 for more than a couple of days.

Mossycat, I hope, with the information from Shaws and hampster1, that you are able to get the tests and treatment you need.

Carolyn x


My full blood count was in range but my B12 levels were 155 (range 150-900) so I think it is possible. I was told by a private Dr that anybody who is hypothyroid should be taking 1000mcg B12 daily.


I have found , together with my gp , that if on the blood test request your gp writes each test ' requested by specialist ' the lab actually carries out the tests from the gp would appear [ in my opinion ] that you have possibly only been tested for tsh ONLY and not for any other --- which all of us know does not give the full picture or treatment options ........ vit's , ferretin ,calcium etc all play a massive part in the CORRECT and optimum treatment of this condition......alan


That must be what happened to my blood test results, only TSH result was showing and TPO , my dr admitted that my antibodies was extremely high, but just said I had to be patient and they will come down slowly but surely, ...leaving me feeling ill and frantic with worry, and again last night my hubby blow his top at ME, and I walked off I returned home and he ignored me completely,so much for making up on Sunday.

, I posted my blood tests here last week but I haven't seen them since!!!


tish, as I have found out in the past year [ with my lady's thyroid problem ] from this site ----and even at my age ....I had a loooong paper round ......[ that's why I look OLD ]......YOU NEED TO INSIST TO YOUR GP TO REQUEST THE FULL TESTS [ and I am still gaining others that need to be done ] ----always remember your gp's practice/trust actually pays the lab's costs [ they CANNOT refuse---even under nhs rules ....if this is done in the correct way ]....your hubby is even more worried than you so remember he cannot YET understand or comprehend the other implications of what YOU are experiencing just give him a cuddle and I am damn sure he will return it ......AND DONT GET RATTY [ even though you may want to ] far as I know with your situation you need to INSIST on t3/t4/calcium/ferritin/iron/b12/b3 tests.....but for now t3 and t4 together with tsh tests NEED to be carried out at the same time for a full 'picture ' of you problem....hope this helps and if I can help in the future please contact me directly.....LoL alan


He he he , I got one up on my usual Dr yesterday, I have been referred back to my Endo, and had one of their blood envelopes left over from last time I saw them, so off I popped to the BRI to their bloods department and marked on the envelope was TSH , Ft4 and I cheekily added t3 he hehe,......ohh that rhymed diderly dee, he he, any way rung the endos secretary this morning and she was very pleased I'd done so!!!! So One point for meeeee, diderly dee, he he

I writing this is bed as I'm aching all over but my sense of humour is still with me he he


Hi there, I believe that adrenal fatigue can produce similar symptoms as those you state. Also, Hashimoto's thyroiditis is suffered by majority of thyroid patients giving these symptoms. Diagnosis is with an antibody test. Treatment is with thyroid hormone, diet change and supplementation. For More info see hashimotos 411 website or Facebook page. It is excellent.


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