I am analyzing serum samples which have been frozen for several years (6 or 7) and I am obtaining some strange results. For example, the same subject showed increased cholesterol, glucose... values when measured recently as compared to 2-3 years ago.
I think it's possible samples have been concentrated because of being frozen for a long time, but I am looking for someone who works in the same conditions or has experience with this type of samples who could confirm this or give me another explanation. Even stranger, in other analysis types like ELISAS...the same samples have shown good results.
Thanks so much in advance