Exercise 6: hematocrit and RBC indices

what specimen is used for hematocrit?

anticoagulated whole blood

what does hematocrit measure?

the percentage of packed red blood cells

what errors can occur duing hematocrit procedure?

incorrectly collected specimen

incomplete sealing of tube or mixing

incorrect speed or time for centrifuge

parallax

parallax 

reading position for hematocrit reader isn’t right over top 

male hematocrit reference range

41-53%

female hematocrit reference range

36-46%

what does increased HCT mean?

not common; extreme dehydration or excess RBC production 

what does decreased HCT mean?

reduction in total RBC volume (anemia)

MCV (mean cell volume)

average RBC volume

increase= macrocytic 

decrease= microcytic

equation for MCV

hematocrit x 10/ RBC count

MCV reference range

80-100 fL

MCH (mean corpuscular hemoglobin)

average hemoglobin mass in RBCs

varies with cell size 

equation for MCH

hemoglobin x 10/ RBC count

MCH reference range

26-34 pg

MCHC (mean corpuscular hemoglobin concentration)

average concentration of hemoglobin in RBCs

% of RBC that hemoglobin takes up

decrease=hypochromia

increase=not possible

equation for MCHC 

hemoglobin x 100/ hct 

MCHC reference range

31-37%

both MCH and MCHC are decreased

microcytic/hypochromic

production defect

both MCV and MCHC are normal

normocytic/normochromic

MCV is increased and MCHC is normal

macrocytic/normochromic

maturation defect

why is hematocrit high at birth?

to maximize oxygen uptake for the baby to increase RBC production

rule of three

HGB x 3 = HCT (±3)

why is not possible for RBCs to be hyperchromic?

they would burst because they can only hold so much hemoglobin