Specimen HandlingQuestion 63 of 100
Within what time should serum or plasma be separated from cells for routine chemistry testing?
a.Within 8 hours of collection
b.Within 24 hours if refrigerated
c.Within 2 hours of collection
d.Only after the specimen has been refrigerated overnight
Explanation
Serum or plasma should be physically separated from the cells within two hours of collection, because continued cellular metabolism lowers glucose and raises potassium, LDH and phosphorus. Holding the tube for 8 or 24 hours before separation produces clinically misleading results. Refrigerating an unseparated tube actually accelerates potassium leakage from red cells.
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