the proportion of immunoreactive somatomedin-c ( ir-sm-c ) in blood that is available for measurement in the ria is influenced by whether the sample is processed as serum or plasma , by how promptly the sample is chilled and frozen , by whether the reaction is carried out in glass or polystyrene tubes and by whether the incubation mixture contains protamine or heparin .
C0229671
serum
C0032105
plasma