HEMATOCRIT - A measurement of the concentration of red blood cells in serum. Expressed as a percent of the blood volume that is occupied by the red cells. Normal values are in the range of 40-54% for males and 37-47% for females. Low hematocrit may indicate anemia, blood loss, leukemia, rheumatoid arthritis, overhydration, multiple myeloma, malnutrition, or bone marrow failure. Higher than normal hematocrits may be seen with burns, dehydration, COPD, eclampsia, erythrocytosis, or polycythemia vera.