So this will also be impacted by the instrument/ machine that your testing facility uses as most standard measurements are done with a method called ECLIA that is basically a less sensitive test and can a lot of times mistakenly cross detect certain metabolites. As an example because deca is a natural occurring hormone in the human body in the form of 19-nor testosterone the eclia measuring tool will mistakenly pick up your Nandrolone and measure it as testosterone.
On the flip side making use of a higher sensitivity machine when doing blood work if you were to test your blood on a nandrolone only cycle while making use of a LC/MS/MS method your free testosterone would come back very low as there is no cross detection due to the high accuracy.
You will also notice when doing a blood test making use of LC/MS/MS that your Estradiol might be lower. Thats because nandrolone aromatises a lot less than testosterone does.
So the detection method your lab uses is very important when determining your blood work.
In doping scenario’s in sports they have to account for the small amount of naturally occurring nandrolone present in the human body when testing for performance enhancing drugs.