Pernicious Anaemia Society
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Confused about TSH, T3 and T4

Hi im a bit confused what is T3 and T4 I know TSH means but alot of people go on about T3 and T4, I have always been tested for TSH but I dont think ive been tested for the other two. Recently as a lot of you know my TSH level was 17.16 which has risen from 0.8 six weeks ago, the Doctors have upped my thyroxine in an effort to correct this. I have started to get my hoarse voice back ago so not sure if my B12 needs topping up (have also been diagnosed with Pernicious Anemia and had a course of 6 injections)

Can anyone help me distinguish between them all

6 Replies

Hi mummytina, all is explained on the Thyroid Uk site, just go to:


Must add that I had B12 deficiency found in 2011, but did not record a hoarse voice among the umpteen symptoms, but I certainly had a hoarse voice years ago when finally diagnosed hypothyroid around 2001.

My own feeling about your soaring TSH is that if this had ever happened to me I would have wanted to be referred to an endocrinologist, but there are people on this site who will be able to advise on this I am sure.

Regarding your diagnosis of PA, you will need to have lifelong B12 injections as your doctor has probably told you. I say this because you write "not sure if my B12 needs topping up" as at a minimum you should have a B12 injection every three months, which is much too long for a lot of people, and if you have neurological symptoms then the British National Formulary which doctors are, or should be, guided by says:

"By intramuscular injection, pernicious anaemia and other macrocytic anaemias without neurological inviolvement, initially 1mg on alternate days 3 times a week for 2 weeksthen 1mg every 3 months.

Pernicious anaemia and other macrocytic anaemias with neurological involvement, initially 1mg on alternate days until no further improvement then 1 mg every 2 months."

Note the difference between the 2 paragraphs, which, alas, many doctors do not.

You can consult the BNF on:

head for Section 9.1.2 Drugs used in megaloblastic anaemias and you can sign in etc. as directed and get half an hour or so to read and print out whatever you need for your own information or even for your doctor.

Hope this helps, sorry if I have told you stuff you may know already.


Thanks very much for the information you have given me this site and all the people on it have been very helpful and have helped me understand more about my problems more than the doctors.

What do you mean by neurological problems what are the symptoms of that, the dr didn't mention that, Do you know if you please let me know then I can see if this applies to me.

Thanks for everything and look forwrad to the answer.


Hi, mummytina, neurological symptoms are demonstrations of nerve damage caused by lack of B12. Different people get different selections of neuro symptoms. The early ones can be mild tingling in the feet and hands. At first, these might only be felt at night in bed. This tingling gradually over the following days and weeks becomes stronger and creeps up the legs and arms. Meantime shooting pains can also develop in the legs; spasmodic movements of the legs in bed; pain in the feet; a strange "switching on" of a feeling as though a lacework of nerves under the skin of the legs had suddenly gone live; painful sparks of points of pain shooting up the legs; a feeling of pain in the thighs like tight muscles or pain in the femur; a loss of perception of sensation leading to numbness perhaps in the legs; or perhaps the fingers so that hot articles can be picked up with no discomfort; unsteadiness showering/dressing; inability to to stand with eyes closed/indark; irritability; wish for isolation.. These all vary form person to person.

The above is just a selection, the PA site on which the forums are open to non-members is invaluable for information.

This link on it might be of initial value to you:


Then there is this other site, also very informative.

Prompt treatment of B12 deficiency whether caused by PA or other conditions, especially by injection of B12 which gets the needed B12 into the bloodstream directly avoiding the causes of malabsorption of B12, in classic PA this is lack of Intrinsic Factor, stops these symptoms and returns the sufferer to normality although this return to normality does not happen overnight. It does sound to me as though your doctor is acting appropriately in the case of your PA diagnosis and that regular B12 injections will follow, but unfortunately I personally, along with many others, have learned not to trust a doctor to do the right thing and it is better for any patient to learn as much as possible themselves. If you have any of the above symptoms or any other symptoms you read of, you should be able to anticipate their disappearance with correct treatment according to the BNF information I have supplied.

Make sure that your folate levels have been assessed, you will find this out by asking for copies of any blood tests and do not be put off asking for them, they are your absolute right. Folate levels should be near the top of the range, for maximum effectiveness of the B12 injections for which the UK uses hydroxocobalamin which has to be methylised by the body using folate in the process. Lack of folate will inhibit the usefulness of B12 injections to the body. Ferritin/iron and Vit D at optimal levels, i.e., not just "in range", or in doctorspeak "normal", but high in the ranges will help to maximise the attention you need for your thyroid problems as well as the PA-caused low B12 level.

I do hope that this helps. I wish you all the best in your learning and recovery path.


Thank you so much you seem to know so much and you have been a good source to help me find out things, I am back for another blood test next week and while I am there I will ask for my blood test results and I will put them on the here and maybe if I can't understand them maybe you or anyone else might be able to.

Thank you once again.


Just a thought, over on the Thyroid UK community there are many very helpful people who can comment on your thyroid issues, if you have not already posted there.


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