Module 3 - Topic 1 - Part 1 & 2 - Complete Blood Count

The purpose of CBC is to identify:

1. anemias

2. infection

3. bleeding disorders

CBC

complete blood count

- lab test that quantifies blood cells and associated indices

Key components of CBC

1. RBCs

2. WBCs

3. Platelets

4. hgb/hct

hgb

hemoglobin

Hct

hematocrit

Why do we order a CBC?

1. detect abnormalities

2. diagnosis and treatment

3. health evaluation

4. Rule out disease

5. monitoring

What protein do eosinophils produce?

MBP

What protein do neutrophils produce?

MPO

What protein do basophils produce?

histamine and heparin

RBCs =

is there anemia?

RBC interpretation includes;

1. hgb

2. hct

3. RBC count

decrease in RBCs

anemia

increase in RBCs

polycythemia

RBC indices =

what type of anemia?

RBC indices include;

1. MCV

2. MCHC

3. RDW

MCV

size (micro/normo/macro)

MCHC

color (hypo/normochromic)

RDW

variation in size

- compare to lymphocyte

WBCs =

infection or inflammation?

WBCs indices include;

total WBC count

- neutrophil

- lymphocytes

- eosinophils

neutrophils

bacterial

lymphocytes

viral

eosinophils

allergy/parasites

platelets indices =

bleeding or clotting risk?

platelet indices include;

platelet count

decrease in platelets

bleeding risk

increase in platelets

clotting risk

RBC count;

number of circulating red blood cells

hemoglobin (Hgb)

oxygen-carrying protein in RBCs

Hematocrit (Hct)

percentage of blood volume occupied by RBCs

WBC count and differential

types of white blood cells and their proportions

platelet count

important for clotting and bleeding disorders

mean platelet volume (MPV)

reflects platelet size and production activity

WBC reported as

10^3 /uL

RBC reported as

10^6/uL

Hct is expressed as

a percentage %

Hct % =

(MCV x RBC) / 10

Hct is

the proportion of blood volume composed of RBCs

Rule of three

1. RBC count x 3 = Hgb

2. Hgb x 3 = Hct %

3. RBC count x 9 = Hct %

rule of three acceptable variance

+/- 3

The rule of three is important in identifying

anemias

MCV

size

MCHC =

concentration / color

MCH =

amount

Hgb give RBCs their

color

MCV measures

Avg RBC size

- microcytic vs macrocytic

MCH measures

Avg Hgb per RBC

- general hemoglobin content

MCHC measures

Hgb concentration

- normochromic vs hypochromic

RDW measures

variation in RBC size

- detects anisocytosis

MCV

mean cell volume

reference interval MCV

80-100 fL

MCV is the most important RBC index in the

initial diagnosis of anemia

increase in MCV =

cells appear large (macrocytic)

decrease in MCV =

cells appear smaller (microcytic)

deviations from normal MCV guides differential diagnosis of

anemia subtypes

microcytic anemia

iron deficiency

macrocytic anemia

B12/folate deficiency

MCH

mean cell hemoglobin

MCH equation =

(Hgb)(10) / RBC

MCH does not reflect

hemoglobin concentration, only total hemoglobin per cell

MCH reference range

27-33 pg

MCHC

mean cell hemoglobin concentration

MCHC equation =

(Hgb)(100) / Hct %

MCHC tells us if RBC is

normochromic or hypochromic

Hypochromic central pallor

> 1/3

hyperchromic central pallor

< 1/3

can ONLY tell the size of an RBC if there is a reference

lymphocyte

hyperchromic is

very uncommon

reference range for MCHC

32-36 g/dL

normocytic, normochromic RBCs

1. same size as lymphocyte nucleus

2. central pallow = 1/3 cell diameter

microcytic, hypochromic RBCs

1. smaller size as a lymphocyte nucleus

2. central pallow = > 1/3 cell diameter

3. cause: iron deficiency

macrocytic RBCs

1. bigger size than a lymphocyte nucleus

2. central pallow = < 1/3 cell diameter

3. cause: B12/folate deficiency

RDW

RBC distribution width

RDW measures

variation in RBC size (anisocytosis)

high RDW indicates

increase in size variability

RDW is useful in distinguishing between

anemias

reference interval range RDW

11.5-14.5%

normal RDW with low MCV =

thalassemia trait

high RDW with low MCV =

iron deficiency

reticulocytes

immature RBCs

reticulocytes contains

residual organelles, including ribosomes for hemoglobin synthesis

normal reticulocyte count in peripheral blood

<3%

>3% reticulocytes in peripheral blood indicates

increase in RBC production

what is one of the most useful test for anemia monitoring

reticulocyte count

what stain is used in reticulocyte count

super vital stain

- stains RNA

super vital stain includes;

1. methylene blue

2. brilliant cresyl blue

MPV

mean platelet volume

increase in MPV =

increase in RBC production

decrease in MPV =

decrease in RBC production

WBC differential

analysis and enumeration of various WBC subtypes

- manual or automated

blood smears are stained with

wright's stain

romanowsky-type stain is the same as a

wright's stain

Wright's stain

a special dye used to stain blood smears so you can see and identify different blood cells under a microscope

Erythrocyte (RBC)

biconcave shape

- size: 7-8uM

- MCV: 80-100fL

central pallor

the central pale area of an RBC that represents the thinnest part of the biconcave disc

- 1/3 of the cell diameter

Anisocytosis

variation in red cell size

Anisocytosis detects;

1. blood smear

2. RDW and MCV

RDW

variation in RBC size (not avg size)

MCV

avg RBC size

Anisocytosis classification

1. macrocytic = larger than normal

2. microcytic = smaller than normal