The effect of recentrifugation of serum separator tubes on concentration of serum analytes

In clinical laboratories, sometimes there is a need to recentrifuge the original tubes ("clot" tubes) in order to better clarify and clean the serum or plasma for further analysis. Also, the original tubes are recentrifuged to ensure there is an adequate volume of serum or plasma for multiple repeating or different tests, and/or to run additional tests that are ordered hours after the original analysis was completed. In our practice, we have encountered that recentrifugation of original tubes, including those with gel separators, does slightly change the concentration of analytes. Although there are two reports on the effect of recentrifugation on serum potassium concentration [1, 2], to the best of our knowledge there are no other studies to show the impact of re-centrifugation on the concentrations of multiple analytes that are routinely measured as part of "metabolic panel". This study investigated the effect of recentrifugation on the concentrations of glucose, sodium, potassium, chloride, BUN, creatinine, bicarbonate, calcium, phosphorus, and magnesium.