Hematocrit

The hematocrit represents the percentage of whole blood volume made up by erythrocytes. Laboratory instruments calculate the Hct from the erythrocyte count and the MCV, ie, Hct = RBC x MCV. 


Normal Range: Male: 39-49 Female: 35-45 Age-dependent


increased in: Hemoconcentration (as in dehydration, burns, vomiting), polycythemia, extreme physical exercise. 
 

Decreased in: Anemia: macrocytic (liver disease, hypothyroidism, vitamin B12 deficiency, folate deficiency), normocytic anemia (early iron deficiency, anemia of chronic disease, hemolytic anemia, acute hemorrhage) and microcytic anemia (iron deficiency, thalassemia). 

 

Additional: Conversion from hemoglobin to hematocrit is roughly Hgb x3 = Hct. Hematocrit reported by clinical laboratories is not a spun hematocrit. The spun hematocrit may be spuriously high if the centrifuge is not calibrated, if the specimen is not spun to constant volume, or if there is "trapped plasma."