Collect light blue top sodium citrate, tube must be full (meet line in the tube near the top of the label). Do not over fill or under fill as it may affect results. The sample must be sent to the laboratory the same day it is draw. Delays in shipping may affect results.

If collected through blood collection set (butterfly), a discard tube must be first drawn to eliminate dead space from tubing.

Causes for rejection include tube under or overfilled, clotted specimen, grossly hemolyzed specimen or grossly lipemic specimen.