Unit 3 - CBC Flashcards
Volume of blood in the body
4-6 Liters
Approximately what % of the total body weight is blood?
8%
What percent of blood is plasma?
~55%
What makes up plasma?
Proteins, electrolytes, hormones
Water
What percent of blood is cellular elements?
~45%
What is the optional component in CBC?
Microscopic evaluation
What does extra anticoagulant do?
Cause shrinkage
Ideal peripheral smears are made within
3 hours
What does EDTA do
Chelates calcium
Perform CBC on room temp blood within
6 hours
Perform CBC on refrigerated blood within
24 hours
When should a sample be prepared for blood smear?
within 2-3 hours of collection
What if a blood smear is prepared after more than 5 hours after collection have passed
Results in artifacts
When is it acceptable to prepare a blood smear without anticoagulant?
Smear from direct finger puncture
When must a finger puncture blood smear be prepared?
Immediately
When to reject CBC specimen?
Too old
Any clotting! even if microscopic
Why is clotting not accepted for CBC specimen?
Activates and consumes coagulation factors
Blood cells bind
WBC reference range in CBC
4.0-11.0x10^3 cells/mcL
No sex difference
RBC reference range in CBC
Male: 4.50-5.90x10^6 cells/mcL
Female: 3.80-5.20x10^6
PLT reference range in CBC
150-450x10^3
No sex difference
Hgb concentration reference ranges
Male: 13.5-17.5 g/dL
Female: 12.0-16.0 g/dL
Hct reference ranges
Male: 42-52%
Female: 36-46%
Which of the indices are not averages?
RDW: Red cell distribution width
What is MCV
Mean corpuscular volume
MCV reference ranges
80.0-100.0fL
Normocytic
80-100fL
Microcytic
<80fL
Macrocytic
> 100fL
What is MCH
Mean corpuscular hemoglobin
MCH Reference interval
26.0-36.0 pg
Normochromic
26.0-36.0 pg
Hypochromic
<26.0 pg
Hyperchromic
> 36.0 pg
What is MCHC
Mean corpuscular hemoglobin concentration
MCHC reference interval
32.0-36.0 g/dL
Which index would you rather use for cell color?
MCHC
What does MCH not take into account?
Cell size
Larger cells have… ___ hgb?
More
Normochromic (MCHC)
32-36 g/dL
Hyperchromic (MCHC)
> 36 g/dL
Hypochromic (MCHC)
<32 g/dL
Hyperchromic is never valid except in…
Spherocytes
What is RDW?
Variation of size in RBC population
MCV Calculation
(HCT/RBC)*10 = fL
MCV is evaluating…
Size of cells
MCH is evaluating…
Concentration of hgb in cell. Evaluating color only
MCHC is evaluating…
Concentration of hgb in cell taking into account size
MCH Calculation
(Hgb/RBC)*10 = pg
MCHC Calculation
(Hgb/HCT)*100 = g/dL
RDW calculation
(1SD of MCV/MCV)*100 = %
High RDW & What it means
> 14.5% indicates the RBC is heterogenous
Anisocytosis
Variation in red cell size
When does high RDW occur?
Diseases with abnormal RBC
Transfusions
Microcytosis (MCV) because denominator is lower
When does Low RDW occur?
No known disease causes this
Macrocytosis can cause a lower number because denominator is higher
What makes a good blood smear?
2/3 to 3/4 of slide
Thumbprint shape
Lateral edges visible
Smear is smooth
Feathered edge
Entire blood drop is used
What components of Wright Giemsa stain ?
Fixative - Methanol
Eosin
Methylene Blue
What pH should romanowski stain be at?
6.4-6.8
Can you wave or blow a blood smear to make it dry faster?
no
High MCV =
Macrocytes
Low MCHC =
Large central pallor
High RDW =
Anisocytosis or variation in abc
What is the rule of 3?
Internal QC check on values related to RBC, Hgb, Hct
Rule of 3 formulas
RBC count x 3 = Hgb
Hgb x 3 = Hct ± 3%