Hemodilution

An increase in plasma volume relative to red blood cell mass, known as hemodilution, can lead to a seemingly lower concentration of red blood cells in the blood, even if the actual number of red blood cells remains the same. 

Hemodilution refers to the dilution of blood components, particularly red blood cells, due to an increase in plasma volume. 

• Dilutional Anemia:In some cases, hemodilution can lead to a condition called dilutional anemia, where the hemoglobin concentration (a measure of red blood cell volume) appears low, but the actual red blood cell volume is normal.  https://www.ncbi.nlm.nih.gov/books/NBK2263