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Thyroid UK
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What should normal thyroid levels be and how does it affect prolactin levels?

My daughter is hypothyroid we have been under endocrinologist since January she is currently taking 75mg levo daily she has improved greatly since January when Tsh was 197 and T4 5.8 but is still always cold and suffers headaches on a daily basis. she recently had thyroid function test at my request because she had high prolactin level of 775 (0-500) reference range. Her T4 was 15 and Tsh 16. This was done through GP and she said because T4 was normal her medication is fine. I am seeing endocrinologist in 2 week s. It has been my understanding that Tsh should be below 5. Do some people just have a high Tsh? or is my daughter undermedicated? Thanks for reading all advice much appreciated.

5 Replies

Trudy44 I wonder why the TSH is so important when a patient is looking for a diagnosis of hypo, ie it usually has to reach the magic number 10 when the reference range is usually something like 0.27-4.20, yet when treated it suddenly becomes unimportant in your daughter's case?? With a TSH of 16 anybody would be diagnosed hypothyroid so I can't understand your GP ignoring it.

In a treated hypo patient the TSH generally should be 1 or below or wherever it needs to be for the FT4 and FT3 to be in the upper part of their respective ranges and the patient to feel well.

Dr Toft, past president of the British Thyroid Association and leading endocrinologist, wrote this in a Pulse Online magazine article:

"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance.

But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."

Maybe your GP would be interested in this. If you email louise.warvill@thyroiduk.org.uk she will let you have a copy of the article which you can print out and show your GP and Endo if necessary.


Thank you for your response and I will get a copy of the article for myself and my Gp. It will be interesting to see what endocrinologist says but she is not the most proactive, doesn't like to give us lab results we only know because my daughter reads them off her screen she just tells us levels normal but Tsh has never been below 10. It is difficult when you feel like you have to fight your corner .


Trudy44 Yes, it is difficult, certainly when we have to fight for ourselves but you have to fight on your daughter's behalf. So you need a plan of action and let the doctors know that you intend to learn all you can and do your best for your daughter so that she doesn't suffer unnecessarily.

Next time the endo says 'normal', get our a notebook and pen, tell her you are doing your best to learn all about this illness so you can help your daughter, that you want to document her progress so will she please give you the name of the test, the result and the reference range. If you don't have the previous figures, ask how the new results compare with the previous ones and write them all down.

Maybe you or your daughter can make a spreadsheet, put the date, time blood was drawn, test name, result, reference range, what dose of meds, how she felt. Update every time. This will be invaluable in the future if any change to dose of meds is suggested (thinking decrease here). You can look back and say..... 'when she was on XX dose of Levo her results were AA/BB and she felt quite good, had energy (whatever). Now you want to reduce her dose back down to YY dose of Levo but when she was on that before she was suffering ...(whatever)... it just doesn't make sense that you would want her to have a return of all those symptoms' ... sort of thing.

Read and learn all you can so that you can discuss with some knowledge. If necessary push for a free T3 test if the endo wants to reduce meds on TSH alone if it's low. We can only be over medicated if our FT3 (the active hormone) is over range, not if the TSH is low or the FT4 is top of range. Push also for antibodies to be tested, both types - thyroid peroxidase and thyroglobulin as TPO can be negative TG can be positive for autoimmune thyroiditis.

On her current results your daughter definitely needs an increase in Levo, the next step would be 100mcg then another test after 6 weeks, then an increase, repeat test in 6 weeks, etc until she gets that TSH down to where it needs to be for her to feel well.

She has an important year coming up with her exams, emphasise to the endo how important this is for her to feel well and to do well at school as her future relies on it.

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To make best use of the Levo vits and minerals need to be good.Suggest you have your daughters folate,ferritin,D3 and B12 tested and post here with the ranges for advice .Under the Data Protection Act your daughter has the right to have the test results.

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I think you need a new doctor..this one will leave her ill. Find a functional medicine doctor, who can show you how to naturally get rid of this and straighten out and save her thyroid gland or google reversing thyroid disease naturally. She should be grain and dairy free and see if it helps. Prolactin raises when hypo..my boobs hurt and felt like rocks. Some people even have milk discharge. It is a pituitary issue.

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