Abaxis VetScan HM5, Operator'S Manual

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A-4 Introduction to Veterinary Hematology
A.3 Blood Cell Parameters
A.3.1 Red Blood Cells, Hemoglobin
Red blood cells — RBC — are formed in the bone marrow. A mature dog red blood cell is non-nucle-
ated, and has a mean corpuscular volume (MCV) of approximately 70 fl. RBCs are the most numerous
cell type in blood. There are approximately 5–10 x 10
12
cells/l in the blood of a healthy dog. RBC
counts and MCV are directly measured primary parameters.
Hematocrit — HCT — is the ratio of the volume of RBCs to the total volume of blood. HCT is the
simplest way to measure the degree of anemia, and is calculated from the RBC and MCV values:
HCT
percent
= (RBC x MCV) / 10
HCT
absolute
= HCT
percent
/ 100
Red Blood Cell Distribution Width — RDW — is a
measure of RBC anisocytosis, the degree of cell size vari-
ation. In a healthy sample, RBCs demonstrate a normal
(Gaussian) distribution (bell curve), as shown at right.
RDW can be characterized by a standard deviation
(RDW-SD) or a coefficient of variation (RDW-CV) repre-
sented as a percentage.
Hemoglobin — HGB — is the main component of RBCs. It is a conjugated protein (with Fe), and its
main function is to transport oxygen from the lungs to tissues and carbon dioxide from the tissues back
to the lungs. HGB is the best measure of blood’s oxygen-carrying capacity.
Mean Corpuscular Hemoglobin — MCH — is the average hemoglobin content of RBCs, and is cal-
culated from RBC and HGB values:
MCH = (HGB / RBC) x 10, reported in picograms or fmol
Mean Corpuscular Hemoglobin Concentration — MCHC — is the concentration of HGB in an
average RBC, calculated from the HGB and HCT values:
MCHC = HGB / HCT
absolute
, reported in g/dl, g/l or mmol/l
Mean Corpuscular Volume — MCV — is the average size (volume) of red blood cells in the blood.