42 yr old male Clin. Details : Hypertension
Anomalous TFTs
TSH(mU/L) fT4(pmol/L) fT3(pmol/L)
Beckman 7.8 21 7.5
Second sample 8.5 21 6.2
Roche(on 2nd sample) 10.7 28.8 8.9
Delfia 9.7 39.4 12.6
(calculated fT4 based on Total T4 & TBG = 29 pmol/l Comment : Poor agreement between fT4 methods suggests assay interference)
We await an equilibrium dialysis fT4.
It’s the first time I’ve come across this sort of interference in three different assays. Does anyone else have any experience of this or suggestions as to what may be causing it? One colleague has suggested
thyroid resistance.
What is the right answer?
Anyone care to try it on a different method?
Michael