How do I learn to interpret my blood test results and general advice

Hi there.Great to be on the site.I had years with UAT without diagnosis.I have been on Levothyroxine for nigh on 20 years now.I have not been told if I have Hashi's.I do not understand the T4 and T3 amounts and what to identify in oder to balance them.I don't feel 100 percent at all and have various symptoms.Drs raise and lower my med amounts and I don't know why,is it due to my hormones changing?Any advice before I ask for my results and try and interpret them.I will also ask if I have Hashi's.I am considering buying Erfa but my GP wouldn't give a prescription.Any advice welcomed.

11 Replies

Welcome to the forum, Alma1.

It will be easier to explain if you can post your results and ranges but generally patients taking Levothyroxine should be looking for TSH around 1.0 or lower with FT4 in the upper quadrant of range. FT3 is rarely tested in primary care but if it is FT3 is usually desirable over halfway through range into the upper third of range. If thyroid peroxidase antibodies are over range it confirms autoimmune thyroid disease (Hashimoto's).

Erfa is NDT which isn't licensed for UK use and therefore rarely prescribed on the NHS. Most members using NDT have private prescriptions or buy online and self medicate.

Before ditching Levothyroxine for NDT it may be worth checking your ferritin, vitamin D, B12 and folate levels as deficiencies are common and can cause symptoms similar to hypothyroid symptoms.

You can private thyroid and vitamin tests if your GP won't order them.

Thank you very much for this.I guess I have to get a private test to find out about Hashi's then.My friend is gluten and lacto free for her Hashi's and it reduced her thyroid attacking antibody level.The GP said my B12 is fine but both parents who have UAT have B12 injections but their deficiency occured in older age.I have had very low vitamin D before but don't know about the folate.What about private prescriptions and monitoring for Erfa?Would I just google a private GP?


You can ask your GP receptionist whether thyroid peroxidase antibodies were tested. Negative TPOab doesn't conclusively rule out Hashi's because some people have positive thyroglobulin antibodies which aren't usually tested in primary care so it may be worth ordering a private thyroid antibody test.

GP's tend to say things are fine when they are within range. When ranges are very broad it can make a lot of difference where in range results are. Ask your GP receptionist for B12 result and range and whether ferritin and folate were tested. If vitD has previously been low and you aren't supplementing D3 you should have vitD retested.

Email for a list of member recommended private doctors. You should check with the doctor that they prescribe NDT before you confirm the booking. You will have to pay for the consultation, any blood tests required to monitor levels and the cost of Erfa prescription.

Thank you so much Clutter for your time and expertise.


Post any results and ranges you get into a new question for advice.

Hi Clutter i got some results from last year when they lowered my Levothyroxine from 150mg to 125mg then I was not retested.It was:

Serum TSH level 0.06 mil [03-4.2]

Serum free T4 level 14.3 pmol/L [9-23 ]

B12 386ng/L [160.-800]

I wondered if these are OK.I am going back for another thyroid test and Vit D and iron next week.


You should have a thyroid test 6-8 weeks after every dose adjustment.

I suspect your GP reduced dose because TSH 0.06 is suppressed and s/he hoped to raise TSH. You weren't over medicated on 150,mcg because FT4 14.3 is less than halfway through range and will probably have dropped lower after the dose reduction.

B12 386 is probably okay but if you have the symptoms of B12 deficiency in go to for advice.

Thank you Clutter.I didn't realise my thyroid level wasn't followed up.At least my B12 is ok.Will look up symptoms though.Grateful for your time and expertise.

Thank you Clutter I will do that.I emailed the address you gave to find out more information.

The thing I found helpful in learning how the thyroid worked and how to understand what was going on was to buy and read this book :

Sometimes there are lots of entries on Amazon for this book with wildly different prices. I suggest checking carefully to make sure you aren't being ripped off. I've even seen the book offered for sale, second-hand, at greater than £40 which is an absolute nonsense!

Thank you humanbean.I need to do some serious learning about it.It's about 17 years too late but hey.

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