How is the packed red blood cell volume commonly determined?

The packed red blood cell volume, also known as hematocrit, is commonly determined by performing a hematocrit test. This test involves collecting a blood sample and then centrifuging it to separate the blood components. The hematocrit measures the proportion of blood volume that is occupied by red blood cells relative to the total blood volume.

This method is direct and standardized, allowing for an accurate assessment of red blood cell mass in relation to plasma. Results from a hematocrit are crucial for diagnosing conditions like anemia and polycythemia, as they provide insights into the number of red blood cells present.

While hemoglobin levels can provide useful information about red blood cells, they reflect the amount of hemoglobin (the protein in red blood cells that carries oxygen) rather than the volume or proportion of red blood cells in the blood. Blood smear analysis gives a visual representation of blood cells and can identify certain disorders but does not measure packed cell volume. Centrifugation alone, without the context of performing an actual hematocrit test, doesn't define the packed red blood cell volume unless the sample is appropriately processed and measured afterward.