L27: Complete Blood Count (CBC) Flashcards by Preethi Gov

What are the major components of a CBC?

Red blood cell count (RBC)

Hemoglobin (HGB)

Hematocrit (HCT)

RBC indices - Mean cell volume (MCV)

Red cell distrubution width (RDW)

Reticulocyte count (RETIC)

White blood cell count (WBC)

WBC differential count (DIFF)

Platelet count (PLT)

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How is WBC, RBC, and PLT measured?

Number of cells per unit volume (µL or L)

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What is HGB?

Hemoglobin

The concentration of hemoglobin in the RBCs (g/dL)

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What is HCT?

Hematocrit

% of packed RBCs per packed volume of whole blood

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What is the rule of three?

When RBCs are normal

HGB x 3 = HCT +/- 3

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What is the reference range for WBCs?

Male and female: 4.5 - 11.5 x 10^3/µL

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What is the reference range for HGB?

Male: 13.5 - 18.0 g/dL

Female: 12.0 - 15.0 g/dL

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What is the reference range for HCT?

Male: 40 - 54%

Female: 35 - 49%

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What is the reference range for RETIC?

< 2.5%

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What is the reference range for PLT?

Male and female: 150 - 450 x 10^3/µL

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What is commonly called H & H?

HGB and HCT

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What counts are higher in newborns and fetuses? Why?

Fetus and newborn have higher HGB, HCT, RETIC bc Hb F (the major hemoglobin in fetus) shifts the O2 dissociation to left resulting in hypoxia

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What does decreased HGB, HCT, RBC count indicate?

Anemia

Decreased production, increased destruction (hemolysis), blood loss, dilutional (increased plasma volume)

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What does increased HGB, HCT, RBC count indicate?

Polycythemia

Benign and malignant causes, severe hydration (decreased plasma volume)

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What is MCV?

Average volume of RBCs (fL)

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What is MCHC?

Hemoglobin concentration in a cell

Average weight of hemoglobin per RBC in pg

Correlates w/ MCV

<30 g/dL is hypochromic

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What is the most important RBC indice?

MCV

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What are RBCs with a normal MCV called? How do they appear on blood film?

Normocytic, normochromic

RBC diameter is normal

Central pallor 1/3 of cell

What are RBCs w/ increased MCV called? How do they appear on blood film?
What are the causes?

Macrocytic

RBC diameter is increased

Found in megaloblastic anemia, myelodysplastic syndrome, bone marrow failure, liver disease

What are RBCs w/ decreased MCV called? How do they appear on blood film?What are the causes?

Microcytic, hypochromic

MCV, MCHC decreased

RBC diameter is decreased

Central pallor > 1/3 of cell

What is RDW?

Red cell distribution width

Measures variation in red cell volume

What does increased RDW correlate with?

Anisocytosis (variation in RBC diameter on a blood smear)

Seen in: Deficiency of iron, vitamin B12, and/or foltate

Hemolytic anemias

Why is it important to look at MCV and RDW together?

MCV can be the same but distribution can indicate abnormalities

What is increased RWD called?

Anisocytosis

How might a bimodal histogram of RDW and RBC occur?

If you have a pt with microcytic anemia and you give them iron and they start producing normal cells

What are retics?

Last immature RBC stage

What is the clinical sue or retics?

Estimate of erythropoietic activity of BM in anemia (or BM's ability to replace RBCs)

What does increased retic count indicate?

Bone marrow responding to anemia Hemolytic anemias, acute hemorrhage, after successful therapy for iron, vitamin B12, or folate deficiency

What does decreased retic count indicate?

Bone marrow NOT responding to anemia Bone marrow failure

What does interpreation of WBC count depend on?

Type of cell affected

What is increased WBC count called? What does it indicate?

Leukocytosis Infections, inflammation, some leukemias

What is decreased WBC count called? What does it indicate?

Leukopenia Some hematologic malignancies, bone marrow failure, megaloblastic anemia

What is WBC differential count?

Proportion of each type of WBC Relative (%) Absolute (# per µL or L)

Is relative or absolute WBC count more reliable?

Absolute

How is absolute count measured?

Absolute count = Total WBC count x % cell

How is absolute neutrophil count (ANC) measured?

ANC = Total WBC x (% Neut + % Bands)

What occurs if instrument differential is abnormal?

Slide is viewed under microscope or w/ digital technology Slide review includes morphology assessment of RBCs, WBCs, PLTs (including inclusions); looking for abnormal or immature blood cells or other abnormal findings

What is left shift?

Shift to the left, band shift Increase in bands and presence of immature neutrophils in PB

What is the clinical correlation of left shift?

Bacterial infections usually present with neutrophilia and a left shift Immature neutrophils also found in PB in myeloid malignancies

What are NRBCs?

Nucleated RBCs

When are NRBCs normally present?

Present in PB of neonates in small #s

What does presence of NRBCs in PB after 4 days of life indicate?

Indicates BM response to severe anemia or disruption of BM (leukemias, other malignancies)

What is increased PLT count called? What does it indicate?

Thrombocytosis Various benign and malignant causes

What is decreased PLT count called? What does it indicate?

Thrombocytopenia Excessive loss, consumption, or destruction Decreased production in bone marrow Maldistribution