Hematocrit Value and Packed Cell Volume

Packed Cell Volume (PCV)

• PCV is the percentage of blood volume that is made up of red blood cells
• Methods for detection: Macro hematocrit method and Micro hematocrit method
• Normal values: Male: 42-52%, Female: 37-47%

Clinical Significance of PCV

• Dehydration: increases PCV
• Polycythemia: increases PCV
• Overhydration: decreases PCV
• Anemia: decreases PCV

Complete Blood Picture (CBC)

• Calculation of cellular elements of blood
• Automated hematology analyzer determines the calculations
• Used to determine general health status, screen for, diagnose, or monitor diseases and conditions that affect blood cells
• Includes: anemia, infection, inflammation, and bleeding disorders

Red Blood Indices

• Mean Cell Volume (MCV): average volume of red blood cell measured in femtoliters (fl)
• Mean Cell Hemoglobin (MCH): average amount of Hb in a single red blood cell measured in picogram (pg)
• Mean Cell Hb Concentration (MCHC): concentration of Hb per 100 ml of RBC measured in g/dl

Erythrocyte Sedimentation Rate (ESR)

• Rate by which red cells sediment when blood is placed vertically in a narrow tube
• Westergren Apparatus: uses a calibrated tube to measure the rate of sedimentation
• Normal values: Male: 4-6 mm/h, Female: 8-10 mm/h
• Clinical significance: increases in inflammatory activity, pregnancy, menstruation, lactation, and certain diseases

Osmotic Fragility Test

• Measures erythrocyte resistance to hemolysis while exposed to varying levels of dilution of a saline solution
• Procedure: uses a series of test tubes with decreasing concentrations of NaCl
• Clinical significance: enzymatic deficiency, hereditary spherocytosis, iron deficiency anemia, thalassemia, and sickle cell anemia