Can a person have a normal red blood cell count, but a low haematocrit?

Answer 1

Yes, but it's not simply dilution. A hyperosmotic volume expantion would increase the osmolarity and decrease the hematocrit. An example of this would be eating dry NaCl or drinking super concentrated salt water. The red blood cell count is the same and the hematocrit would decrease. In this case, the hematocrit decreases because of dilution and because water flows out of the RBCs.
The IV fluid is generally an isosmotic volume expansion, and it would decrease the hematocrit by simple dilution.

Answer 2

Yes.

The red cell count (RBC) only indicates the number of cells that are seen on a slide or detected in a sample by a machine.

The haematocrit (HCT) indicates the amount of hemaglobin in the red blood cells of that sample.

In dilutional states, i.e. fluid overload, poor sampling, etc, the RBC value and the HCT value will both be low.
In the example above with hypertonic salt solution, the RBC and HCT will both still be lower due to dilutional effects since only the water leaves the RBCs not the hemaglobin. The cells will shrivel in size (in the worst case scenario) but the number of cells or the amount of hemaglobin in the cells won't change.

If a person is mildly iron deficient, his bone marrow may still be producing the normal number of cells (i.e. normal RBC), however each cell may have a lower concentration of hemaglobin resulting in a lower HCT.

Answer 3

Yes, its often seen in a dilution state. Anything that dilutes the blood makes your Hematocrit run low, but doesnt affect your RBC ct.

An example would be IV fluids

Answer 4

ha ha let me guess - u got intro to lab prac cw in for tomro??? lol me too! thanks for askin this question! :)