New Thyroid function tests values UK

[Haddockfishface]

Hi everyone. I had my TSH, Serum free T4 and T3 checked last week. I left 26 hrs since my last dose of 150 prior to the test.I requested a copy of my results

Lab note states

All biochem methods have changed. New reference ranges may apply and some results will not be directly comparable to previous.

Please refer to Path Handbook or contact lab for more info......

Has any one else aware of this change???

TSH 0.192 mu/L No action required

range 0. 27 -4.40 mu/L

Serum free T4 19.8 pmol/L NORMAL

Range 12.00- 22.00pmol/L

Serum Free T3 4 6 pmol/L NORMAL

Range 3 .10- 6.80pmol/L

BUT it says Values <8pmol/L approx 15% lower than test results pre this test.

[SlowDragon Administrator]

Welcome to the forum

Do you always get same brand levothyroxine at each prescription

What vitamin supplements are you currently taking

When were vitamin D, folate, ferritin and B12 levels last tested

Free T4 (fT4) 19.8 pmol/L (12 - 22) 78.0%

Free T3 (fT3) 4.6 pmol/L (3.1 - 6.8) 40.5%

Most people when adequately treated will have BOTH Ft4 and Ft3 approx 70% through range

So, like many patients on just levothyroxine you have low Ft3

What was reason for thyroidectomy?

Poor conversion of Ft4 to ft3 is often improved by getting vitamins at OPTIMAL vitamin

So first step is to get vitamin levels tested

Low Ft3 leads to low vitamin levels…..low vitamin levels leads to poor conversion rate

Frequently necessary to supplement continuously to maintain optimal vitamin D and folate and B12

Usually just vitamin D and vitamin B complex…..if B12 is particularly low a separate B12 too initially

If ferritin is below 50, a full iron panel test for anaemia including ferritin to see if need iron supplement

[Lalatoot]

Haddock, each lab sets its own ranges based on its equipment and the local population. so the changes at that one lab apply only to that one lab.

On here you will see folks talking about percentage through range. For example my ft4 is 50% through range and my ft3 72% through range. This is how you compare your result between different ranges ie my ft4 should be 50% of any range so if the range was 10 - 20 my result should be 15. If the range was 9 - 25 my result should be 17 if I tested at that lab.