Specimen Handling and Processing Flashcards

What is the primary reason for centrifuging a blood specimen after collection?

Answer: To separate cellular components from serum or plasma

Centrifugation uses centrifugal force to separate the heavier cellular components from the lighter serum or plasma, allowing testing on the liquid portion.

Which specimens must be protected from light during transport to the laboratory?

Answer: Bilirubin and vitamin B12 specimens

Bilirubin and vitamin B12 are light-sensitive analytes that degrade when exposed to light, requiring amber tubes or foil wrapping during transport.

What happens to potassium levels in a specimen that is hemolyzed?

Answer: Potassium increases significantly

Hemolysis releases intracellular potassium from ruptured red blood cells into the serum, falsely elevating measured potassium levels.

What is the maximum time a serum specimen should remain on the clot before centrifugation?

Answer: 2 hours

Serum specimens should be centrifuged within 2 hours of collection to prevent glycolysis and other cellular metabolic changes from altering analyte concentrations.

Why must a blood gas specimen be placed on ice immediately after collection?

Answer: To slow cellular metabolism that consumes oxygen and produces carbon dioxide

Ice slows the metabolic activity of blood cells, which would otherwise consume oxygen and produce carbon dioxide, changing the pO2 and pCO2 values.

What is the correct procedure for aliquoting serum from a centrifuged tube?

Answer: Use a clean disposable pipette to transfer serum without disturbing the cell layer

A clean disposable pipette should be used to carefully transfer serum from above the gel or cell layer without disturbing it, preventing cellular contamination.