Hematology Instruments and Blood Cell Measurements

what parameters are typically recorded in a CBC

Erythrocyte parameters (Hematocrit, hemoglobin, RBC count)

-MCV, MCH, MCHC, RDW

Leukocyte counts (total leukocyte and differential leukocyte counts)

Platelet count

using the impedance method, change in resistance is proportional to

cell volume

cats have ____ platelets

big!!!!

what is the impedance instrument useful for

cell count and size, provides cell volume distributions

measure Hb spectrophotometrically

WBC and platelet counts

what can the impedance instrument not be used for

reticulocytes

intracellular characteristics of cells

accurate platelet counts in cats

What limitation does impedance technology have for WBC differentials?

only a 3-part differential based on size, which has limited accuracy

what is laser flow cytometry useful for

determines number, size, and internal complexity of cells

reticulocyte counts!

5 part differential counts and total WBC

what is laser flow cytometry not useful for in dogs

basophils

what does forward scatter measure

cell size

what does side scatter measure

cells internal complexity or granularity

what is an example of a cell with high side scatter

neutrophils

what is an example of a cell with low side scatter

lymphocytes

RBC count itself has

little value, use it to calculate MCV and MCH manually and Hct electronically

MCV stands for

mean cell volume

MCH stands for

mean cell hemoglobin

MCHC stands for

mean cell hemoglobin concentration

RDW stands for

red cell distribution width

MCV measures

average volume of single erythrocyte

MCH measures

average amount of hemoglobin in single erythrocyte

what does MCHC represent

represents Hb concentration per dL of packed RBC

when is MCH lowest

severe iron deficiency anemia

what does RDW measure

coefficient of variation of erythrocyte volumes

electronic measure of ansiocytosis

only what kind of reticulocyte counts are measured in most instruments

aggregate reticulocytes

what causes spuriously increased RDW

erythrocyte agglutination

platelets counted in erythrocyte histogram for severely anemic patients

platelet aggregates can result in

false thrombocytopenia

-due to platelet activation during blood collection

how are automated reticulocyte counts performed

flow cytometry

what must be verified when measuring automated reticulocyte counts in cats

validated with manual count

confirm that only aggregate reticulocytes are counted

what causes spuriously increased MPV

platelet aggregates

storage of blood at 5C

what error occurs due to nucleated erythrocytes in blood

counted as leukocytes, correct by calculating total leukocyte before calculating absolute differential leukocytes

what are some causes of sample errors in blood cell measurement

old blood samples

platelet, leukocyte, erythrocyte aggregates

clot formation

precipitate below body temp

how can lipemia affect blood cell measurements

Hb and MCHC increased falsely

how can heinz bodies affect blood cell measurements

Hb and MCHC increased

sometimes increases leukocyte and reticulocyte counts

how is MCV determined

hematology analyzers

what is used to calculate MCHC

hemoglobin and hematocrit