L27: Complete Blood Count (CBC) Flashcards
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)
How is WBC, RBC, and PLT measured?
Number of cells per unit volume (µL or L)
What is HGB?
Hemoglobin
The concentration of hemoglobin in the RBCs (g/dL)
What is HCT?
Hematocrit
% of packed RBCs per packed volume of whole blood
What is the rule of three?
When RBCs are normal
HGB x 3 = HCT +/- 3
What is the reference range for WBCs?
Male and female: 4.5 - 11.5 x 10^3/µL
What is the reference range for HGB?
Male: 13.5 - 18.0 g/dL
Female: 12.0 - 15.0 g/dL
What is the reference range for HCT?
Male: 40 - 54%
Female: 35 - 49%
What is the reference range for RETIC?
< 2.5%
What is the reference range for PLT?
Male and female: 150 - 450 x 10^3/µL
What is commonly called H & H?
HGB and HCT
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
What does decreased HGB, HCT, RBC count indicate?
Anemia
Decreased production, increased destruction (hemolysis), blood loss, dilutional (increased plasma volume)
What does increased HGB, HCT, RBC count indicate?
Polycythemia
Benign and malignant causes, severe hydration (decreased plasma volume)
What is MCV?
Average volume of RBCs (fL)
What is MCHC?
Hemoglobin concentration in a cell
Average weight of hemoglobin per RBC in pg
Correlates w/ MCV
<30 g/dL is hypochromic
What is the most important RBC indice?
MCV
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
