Thyroid UK
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Interpretation of results please

I'm hoping someone can shed light on whether my NDT is working as my GP is concerned about my low TSH and has referred my to an endo with a view to taking Levothyroxine.

Results 6 months ago (pre -NDT):-

Serum free T3 4.4pmol/L (3.5-6.5)----normal

Serum free T4 10pmol/L (9-23)-----normal

Serum TSH level 4.8 mu/L (0.55-4.8)--normal

Results on 4th November after getting my NDT intake up to 4 grains per day (from mid-October, up from 2 grains):-

Serum free T3 6.4 pmol/L (3.5-6.5)----normal

Serum free T4 10 pmol/L (9-23)-----normal (although verbally GP says she's seen recent result of 8 pmol/L)

Serum TSH level 0.04 mu/L (0.55-4.8)--abnormal

Folate - >24

Vit D - 106

Ferritin - 13 (I'm aware this is low and am taking Spatone now)

Vit B12 - 616

Calcium - 2.28

Adj calcium conc - 2.29

Serum albumin - 41

From what I've read on this site my low TSH shouldn't be a concern but am I right in thinking I need to get my T4 up? If so should I increase my NDT dose?

I've been told I have Hashimoto's. I also have Rheumatoid arthritis and have been taking Methotrexate for the last 10 weeks and I'm not sure whether this will affect my thyroid condition.

Although my GP seems concerned about my results I actually have more energy than I've had in a long while. My main symptom is a 'stuffy' head and a blocked ear but I think this is my recurring otitis externa (although I did note on a recent post that one symptom of a dysfunctional thyroid is blocked ears!).

Any help would be appreciated.

2 Replies


FT4 is usually lower when taking NDT than previously when taking Levothyroxine. It really doesn't matter that FT4 is low (even below range) as long as FT3 is good. Your FT3 remains within range so you are not over medicated on your current dose even though your TSH is now suppressed. You shouldn't increase dose as your FT3 will be pushed over range. If you feel better taking NDT there's no point in seeing an endo who's intent is to get you back on to Levothyroxine which presumably didn't suit you previously.

Folate, vitD and B12 are good. You haven't included calcium ranges but I think 2.29 is usually within range.


I am not a medical professional and this information is not intended to be a substitute for medical advice from your own doctor. Please check with your personal physician before applying any of these suggestions.


Depends what you mean by 'working'. I would have thought that the suppressed TSH was one proof that it was 'working', because that's what it's supposed to do - increase thyroid hormone levels until the pituitary no-longer feels the need to secret TSH.

As Clutter said, it doesn't matter about the FT4, as long as the FT3 is good. And yours would seem to be - that your FT3 has come up so much is more proof that NDT is 'working'. But, the ultimate proof is how you feel. If you feel good, then that is all that matters! Don't change a thing! :)


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