- Some apheresis donors may be asked to have a second procedure in which they take calcium according to standard guidelines for plateletpheresis and leukapheresis. During the second procedure, platelet donors will take oral calcium tablets before starting plateletpheresis. White cell donors will receive calcium intravenously (through a vein) during the second leukapheresis. For this second procedure, the donors provide additional blood and urine samples as described above.