Synonyms

   PCV (Packed Cell Volume),Haematocrit (Hct), Erythrocyte volume fraction (EVF)

Clinical Significance

   PCV is the ratio of the volume of erythrocytes to that of whole blood and is reported as percentage. PCV is the earliest RBC parameter identified and is used for red cell disorders differentiation. PCV is one of the most precise methods of determining the degree of anemia or polycythemia.

Specimen

   Whole blood 1ml or 3ml

Stability

   24 hours at 20 - 25 ˚C

   72 hours at 2 to 8 ˚C

   7 days at -20 ˚C

Reference Range

   Male : 42.0 – 48.0 %

   Female : 40.0 – 45.0 %

Interpretation

   PCV is decreased in:

       Blood loss

       Bone marrow failure

       Erythropoietin deficiency

       Hemolysis

       Leukaemia

       Malnutrition

       Multiple myeloma

       Autoimmune disease such as SLE and Rheumatoid arthritis

   PCV is increased in:

       Dehydration

       Kidney disease with high erythropoietin production

       Low oxygen level in the blood

       Congenital heart disease

       Cor pulmonale

       Pulmonary fibrosis

       High altitude

       Polycythemia vera

       Smoking

Limitation

   PCV may be normal or high in patients with shock or with volume depletion due to hemoconcentration despite a decreased red cell mass. Inappropriate concentration of anticoagulants, poor mixing of samples, or insufficient centrifugation sometimes cause technical error in manual PCV determination. Also errors of automated PCV calculation are more common in patients with polycythemia or abnormal plasma osmotic pressures.