CBC and Peripheral Blood Cell Morphology

Question 1

What are the specimen requirements for a CBC?

Answer 1

EDTA anti coagulated blood (purple top)

Question 2

What 3 cell types are counted by CBC?

Answer 2

leukocytes, erythrocytes, thrombocytes

Question 3

Hemoglobin (Hgb)

Answer 3

• reported in g/dL
• uses cyanmethemoglobin method for measurement
• gives the total hemoglobin concentration in a given volume of blood (NOT PER CELL)
• improper venipuncture can affect results, especially with finger stick samples or capillary blood samples

Question 4

Hematocrit (Hct)

Answer 4

• “packed cell” volume, reported in %
• volume percentage of RBC in blood
• Hct = MCV x RBC
• in nml individuals, Hct is 3x Hgb which is 3x RBC count

Question 5

Mean corpuscular volume (MCV)

Mean corpuscular hemoglobin (MC)

Answer 5

MCV

• RBC indicies, in fL
• avg vol of RBCs, correlating with avg RBC size
• MCV = Hct x 1000/RBC
• useful in evaluation of anemia, although may be nml in early deficiency anemias (like iron, B12, folate def)
• small cells have small MCV, large cells have large MCV

MCH
- reported in pg
- weight of Hgb in the average RBC
- calculated from total Hgb concentration and RBC total count
MCH = Hgb/RBC
* doesn’t take into account the size of cell

Question 6

Mean corpuscular (cellular) hemoglobin concentration (MCHC)

Answer 6

• RBC indices
• concentration of Hgb in the avg RBC
• calculated from the Hbg concentration and Hct
• MCHC = (Hgb/Hct) x 100

*normochromic cells have normal MCHC, hypochromic cells have lower MCHC

Question 7

Red blood cell distribution width (RBW)

Answer 7

• measurement of variation in size of RBC

- anisolytosis = abnml variation in size (high RDW) with wider peak on graph

Question 8

Mean platelet volume (MPV)

Answer 8

• reported in fL
• measurement of variation in size of platelets, analogous to MCV in erythrocytes.
• an indirect measure of the age of platelets. newer, more immature ones tend to be larger than older ones

Question 9

Leukocyte differential

Answer 9

• divided into granulocytes (neutrophils, bands, immature granulocytic precursors), lymphocytes, monocytes, eosinophils, and basophils

Question 10

Absolute vs. relative counts

Answer 10

absolute counts - real cell number; calculated by multiplying the % on the manual differential by total WBC count **this is the count that matters

relative counts - percentages, relative numbers

Question 11

Leukocytosis

Answer 11

increased WBC

Question 12

Neutrophilia

Answer 12

increased neutrophils

Question 13

eosinophilia

Answer 13

increased eosinophils

Question 14

basophilia

Answer 14

increased basophils

Question 15

monocytosis

Answer 15

increased monocytes

Question 16

lymphocytosis

Answer 16

increased lymphocytes

Question 17

thrombocytosis

Answer 17

increased platelets

Question 18

polycythemia

Answer 18

increased RBC

Question 19

leukocytopenia

Answer 19

decreased WBC

Question 20

neutropenia

Answer 20

decreased neutrophils

Question 21

lymphocytopenia or lymphopenia

Answer 21

decreased lymphocytes

Question 22

monocytopenia

Answer 22

decreased monocytes

Question 23

thrombocytopenia

Answer 23

decreased platelets

Question 24

anemia

Answer 24

decreased RBC

Question 25

microcytic

Answer 25

decrease RBC cell size (<7 microns, <80 fL)

Question 26

microcytic

Answer 26

larger than nml RBC (>8.5 microns, >100 fL)

Question 27

anisocytosis

Answer 27

variation in size

Question 28

poikilocytosis

Answer 28

variation in shape

Question 29

anisopoikilocytosis

Answer 29

variation in size and shape

Question 30

normocytic

Answer 30

nml amount of Hgb, with nml staining on peripheral blood smear

Question 31

hypochromic

Answer 31

decreased Hgb, with pale staining

Question 32

polychromasia

Answer 32

increased immature RBC (reticulocytes); blue-gray cytoplasm due to residual RNA; nml act of Hgb

Question 33

Describe normal erythrocytes.

Answer 33

- biconcave discs in peripheral blood (flexible) - roughly circular in shape on peripheral blood smear, with minor variations in size and shape - average diameter about 7.5-8um - central zone of pallor occupies approx. the middle third of the cell - main function: carry O2 in arteriolar blood to tissues and CO2 back to lungs

Question 34

Abnormalities in size: microcytic hypochromic cells

Answer 34

cells are small and pale; zone of central pallor is >1/3 the diameter of cell seen in iron deficiency, anemia of chronic dz, sideroblastic anemia, lead or other heavy metal poisoning, and thalassemia

Question 35

Abnormalities in size: macrocytic anemia

Answer 35

cells are larger than nml, well hemoglobinized (normochromic); seen with young cells and in abnormal maturation states like megaloblastic anemia (B12 or folate deficiency_, and myelodysplastic syndromes

Question 36

Abnormalities of shape: spherocytes

Answer 36

cells are smaller in diameter than nml but spherical with loss of central pallor; bone marrow produces nml biconcave red cells but these lose membrane during passage through the spleen; spherocytes have shortened lifespans and destroyed prematurely in spleen - denser in color