What does the microhaematocrit centrifuge do?

• A. Separates plasma from serum
• B. Specific for PCV and total protein of blood
• C. Measures blood sugar
• D. Determines white blood cell count

Answer: (B)

The microhaematocrit centrifuge is used to quickly determine the packed cell volume (PCV) by centrifuging a capillary blood tube until the red blood cells pack at the bottom and the plasma rises to the top. Reading the height of the packed cell layer as a percentage of the total tube gives the PCV, a measure of how concentrated the red cells are in the blood. The plasma portion at the top can then be used to estimate total protein, typically with a refractometer. So this device is used for PCV measurement and for obtaining plasma for total protein assessment. It’s not used for measuring glucose or directly counting white blood cells, and the key outcome is PCV plus plasma protein, not plasma–serum separation per se.