As an update, medichecks confirmed they do use Roche ECLIA as opposed to LC/MS/MS.
This confirms
@mands suspicion that this cross reactivity could be the reason.
I'm going to add my lower than mid range E2 into the mix. I have no idea what my baseline is but IF I react like most i.e higher test equals higher E2 then in theory my E2 should be significantly higher. However, this is obviously an educated guess.
As mands eluded to, my test levels would be consistent with 650mg of test. He also indicated that if ECLIA resulted in 100% cross reactivity of nandrolone then there is real possibility that the lab test could well be the reason for a false test reason. It could also actually mean it's also pretty accurately dosed as well.
One thing I'm glad about is the fact I didn't stamp my feet and start shooting my mouth off. I posted and members helped.
If you are kind enough to read this, this may be common knowledge to you, if not, look at the first sticky (tren results in high E2 and DECA results in high test in many cases). . It does ring a bell that I may have already read this but it didn't stick. Also refer to the paper mands posted
I want to thank both mands and
@jano for their input. It has been a great help for me in maintaining an open minded view even if I did think, "oh shit" at first. I bow to their knowledge. Not a bad community hey.
Now this ain't definitive but I'm a lot more reassured that my DECA is DECA. A lab analysis of each compound would confirm but I can't see me being comfortable sending it off (just being honest).
Another way (not definitive but indicative) may be to drop the DECA, stick with test only but increase it to gauge my E2 levels. IF it raises it notably then in theory, it would indicate that on 650mg test, it would be a hell of a lot higher and my DECA ain't test.
Thanks again guys, I may do as above just out of curiosity but for now I'll have faith my initial research is still a good punt.