Hematocrit and RBC Indices

TRUE about indirect hematocrit determination (more than 1 answer required)

• incorporated in automated hematology analyzers

• calculated from RBC count and MCV

• utilizes the spun microhematocrit method

• makes use of EDTA as the anticoagulant

Anticoagulants in the Wintrobe macrohematocrit method (more than 1 answer required)

• sodium oxalate

• double oxalate

• heparin

• EDTA

Proper sealing of capillary tubes

• 4 mm, clay then paraffin

• 4 mm, paraffin then clay

• 8 mm, clay then paraffin

• 8 mm, paraffin then clay

Solve for Hct value given the following:

height of entire blood column: 65 mm

height of buffy coat: 15 mm

height of RBC: 27 mm

• 42% normal

• 34% decreased

• 65% increased

• 18% decreased

Centrifugation for macrohematocrit

• 2500 x g for 30 minutes

• 10,000 x g for 30 minutes

• 3,000 x g for 30 minutes

• 15,000 x g for 30 minutes

Minimum required height of the entire blood column in microhematocrit

• 5 cm

• 6 cm

• 7 cm

• 8 cm

Expected Hct value of a patient with anemia

• increased

• decreased

• normal

• variable

Microhematocrit value if tube is centrifuged at 13,000 x g for 5 min

• falsely low

• falsely high

• no erroneous effect

• variable effect

Effect of anisocytosis and poikilocytosis in Hct values

• falsely low

• falsely high

• no erroneous effect

• variable effect

Causes of falsely high Hct value (more than 1 answer required)

• 3ml blood in a 5ml-EDTA tube

• Hct performed 10 hrs after venipuncture

• patient who is dehydrated

• heparinized blood centrifuged at 3,000 rpm for 5 min