Graves'/Hyper - difference between Medichecks and NHS blood tests?

[BridlePath]

Firstly, thank you to forum members who kindly responded to my earlier posts regarding my diagnosis with Graves’ disease – much appreciated. I read the forum regularly and gain much understanding from the experience and knowledge of others.

Can anyone advise me on what significance, if any, I should attach to the difference between the NHS and Medichecks Thyroid function blood tests I had done last week. I am about to have a follow up with the consultant who is treating me for hyperthyroidism due to Graves’ disease so I wanted a test which included T3.

Tests were done 24 hrs apart, both at around 9am, fasting, with blood draw.

Medichecks

TSH 0.018 (0.27 – 4.2)

T4 16.6 (12-22)

T3 5.4 (3.1-6.8)

NHS

TSH <0.05 (0.2-4.3)

T4 13.4 (7.8-18.0)

Though I am a maths dunce, I believe the Medichecks test shows T4 at 46% through range, T3 at 62% and the NHS test shows T4 at 54%.

The Medichecks test (for TSH at least) appears to be more sensitive as the latest test shows a slight rise in TSH from my previous Medichecks test in September which recorded TSH of <0.005 (0.27 – 4.2) whereas the NHS tests have consistently recorded TSH at <0.05 (0.2-4.3).

For context I have been taking Carbimazole since September, starting on 20mg daily, and am now down to 5mg – T4 has risen slightly from 12.0 (7.8-18.0) recorded at last NHS test in mid-December when dose was reduced from 10mg to 5mg.

[tattybogle]

yes , the TSH assay (test machine) used by your NHS lab can't accurately measure below 0.05 hence the <

medichecks must be using one which can report lower numbers more accurately .

ft4 assays are a bit variable anyway, lots of different assays / ranges in use , so the difference between 46/ 54% from different assays is not a concern . you can safely interpret your ft4 results as 'around 50%'

[BridlePath in reply to tattybogle]

Thank you, tattybogle, that makes sense and useful to know.