Lab Evaluation of RBCs Flashcards
Manual RBC Intro to Hemacytometers Retic Counts Manual Hb, Microhematocrits, ESRs, RBC Indices
RBC count (manual or automated) - Basic procedure
Whole blood diluted w/ isotonic diluting fluid and RBCs counted
RBC count (manual or automated) - Normal (adult) reference values
4-6 million /mm^3
- NOTE DIFFERENCES B/W MEN AND WOMEN
Retic count
- Basic procedure
Whole is diluted w/ supravital stain, smears made, retics count–expressed as %
Retic count
- Normal (adult) reference values
0.5-1.5%
Hemoglobin
- Basic procedure
Whole blood is diltued w/ reagent containing a lysing agent
Hemoglobin
- Normal (adult) reference values
Male: 14-18 g/dL
Women: 12-16 g/dL
Microhematocrit
- Basic procedure
Whole blood spun down 5 minutes in 2 microhematocrit tubes, sealed at one end w/ clay; determined using reader
Microhematocrit
- Normal (adult) reference values (% of packed cell volume)
Men: 42-54%
Women: 36-48%
Erythrocyte sedimentation rate (ESR)
- Basic procedure
Allow specific amount of blood to sit in vertical position for 1 hour; measure how far, in mm, that RBCs fall
Erythrocyte sedimentation rate (ESR)
- Normal (adult) values
Men: 0-15 mm
Women: 0-20 mm
Volume factor for all 9 squares on a hematocytometer
1/(1 x 1 x 0.1 x 9) = 1.1
Volume factor for 4 W corners on a hematocytometer
1/(1 x 1 x 0.1 x 4) = 2.5
Volume factor for center square on a hematocytometer
1/(1 x 1 x 0.1 x 1) = 10
Volume factor for manual RBC area on a hematocytometer
1/(0.2 x 0.2 x 0.1 x 5) = 50
Retic counts
- Type of stain used
Supravital
Retic counts
- Two retic stains commonly used
- New methylene blue
- Brilliant cresyl blue
Retic counts
- Composition of reticulum
RNA
Calculate uncorrected retics
(# retics/1000) = (x/100)
- Expressed as a %
Calculate corrected retics
observed retics x (patient’s Hct/”normal” Hct)
Calculate RPI
(corrected retic count)/2
Calculate absolute retic count
(uncorrected retic count x RBC count)/100
Form of Hb that can’t be measured by cyanmethemoglobin method
Sulfhemoglobin
4 causes for falsely elevated Hb determination
- High WBC count (>20,000/mm^3)
- High PLT count (>700,000/mm^3)
- Lipemia
- RBCs resistant to hemolysis (Hb-S, Hb-C)
Rule of 3
- RBC x 3 = ~ Hb
- Hb x 3 = ~ Hct +/- 3
Predict causes for discrepancies w/ regard to Hb and Hct not being “in balance”
??
Undercentrifugation will ____ Hct
Falsely ↑
↓ blood: anticoagulant ratio will ____ Hct
Falsely ↓ (“short draw”)
EDTA tube allowed to set out all night at room temp will ____ Hct
Falsely ↑
- Glucose is used up (4-6 hours), cell membrane breaks down and fluid leaks into cells making them more spherical)
Buffy coat included in reading will ____ Hct
Falsely ↑
3 stages that occur during 60-minute setting period of ESR
- Rouleaux (~10 minutes)
- Rapid fall (~40 minutes)
- Packing (~10 minutes)
How does an ↑ in plasma proteins affect ESR?
↑ plasma proteins coats RBCs → ↓ zeta potential (surface charge becomes more positive) → RBCs stick together more → ↑ rouleaux → ↑ mass → bigger fall → ↑ ESR
Plasma proteins w/ the greatest affect on ESR
Fibrinogen
↓ blood:anticoagulant ratio will ____ ESR
Decrease
- B/c of ↑ [anticoagulant], RBCs become spherical inhibiting rouleaux
EDTA blood tube allowed to sit out overnight at room temp will ____ ESR
Decrease
- As glucose is used up (4-6 hours), cell membrane leaks fluid into RBC causing them to become spherical which affects rouleaux; if there’s poik cells, then RBCs won’t rouleaux
Sedimentation tube isn’t perpendicular will ____ ESR
Increase (even a slight tilt)
Rack holding tubes placed next to a centrifuge will ____ ESR
Increase (from vibrations)
Average RBC volume
MCV
MCV formula
(Hct x 10)/RBC count
Normal MCV range
80-100 fL
RBC morphology seen w/ decreased/increased MCV
Decreased MCV → microcytic
Increased MCV → macrocytic
Average RBC Hb mass
MCH
MCH formula
(Hb x 10) /RBC count
Normal MCH range
27-31 pg
Average relative [Hb] per RBC; relates to stained RBC color intensity
MCHC
Normal MCHC range
32-36% (spherocytes)
RBC morphology seen w/ decreased/increased MCHC
Decreased MCHC → hypochromic RBCs
Increased MCHC → >38% should not happen! (Incorrect calc? Lipemia? Cold agglutinin?)
Technique used to determine size of RBC by comparison w/ small lymphocyte
Find small, resting lymphocyte; RBCs should be about the size of the nucleus of the lymph or about 2/3 the size of the lymph itself
Variation in RBC diameter (or volume) on blood film; correlates w/ RDW (> 14.5%)
Anisocytosis
Presence in PB of RBCs w/ varying or bizarre shapes
Poikilocytosis
Young non-nucleated RBCs that still contain some basophilic substance (RNA)
Polychromasia
Small RBC w/ reduced MCV (
Microcyte
RBC w/ abnormally large diameter seen on PB film and elevated MCV (> 100 fL)
Macrocyte
Acanthocyte
- Morphology
- Disorders/conditions
- Lack central pallor, multiple irregularly spaced projections of varying length
- Abetalipoproteinemia (hereditary)
Blister cell
- Morphology
- Disorders/conditions
- Heinz bodies pitted out by healthy spleen
- Burn patients, DIC
Burr cell
- Morphology
- Disorders/conditions
- Short, evenly spaced projections usually w/ central pallor
- HUS, PK deficiency
Crenation
- Morphology
- Disorders/conditions
- Almost always a drying artifact
- Severe electrolyte imbalance
Elliptocytes
- Morphology
- Disorders/conditions
- Cigar-shaped
- Hereditary elliptocytosis
Hb C crystals
- Morphology
- Disorders/conditions
- Dark red, hexagonal
- Homozygous Hb C disease
Hb SC crystals
- Morphology
- Disorders/conditions
- Dark red, 1-2 fingerlike projections (mitten-shaped)
- Hb SC disease
RBC clumps (agglutination)
- Morphology
- Disorders/conditions
- Clumping
- Ag-Ab reactions
Rouleaux
- Morphology
- Disorders/conditions
- Stack of coins
- Multiple myeloma
Schistocytes
- Morphology
- Disorders/conditions
- Fragments
- Burn patients, DIC
Sickle cells
- Morphology
- Disorders/conditions
- Elongated cell w/ point on each end; may be curved or S-shaped
- Sickle cell anemia (homozygous Hb SC disease)
Spherocytes
- Morphology
- Disorders/conditions
- Round, no central pallor; darker color than surrounding RBCs
- Hereditary spherocytosis, burn patients, thalassemia, transfusion w/ old blood
Stomatocytes
- Morphology
- Disorders/conditions
- Slit-like area of central pallor
- Rh null disease
Target cells
- Morphology
- Disorders/conditions
- Bull’s eye
- Thalassemia
Tear drops
- Morphology
- Disorders/conditions
- Shaped like tear drop or pear
- Tumor in BM
Mixed cell population
- Morphology
- Disorders/conditions
- 2 distinct RBC populations
- Sideroblastic anemia, transfusion therapy
Macroovalocytes
- Morphology
- Disorders/conditions
- Egg-shaped
- Megaloblastic anemia
Round macrocytes
- Morphology
- Disorders/conditions
- Associated w/ hemolytic conditions → reticulocytosis
Basophilic stippling
- Composition of inclusions
- Disorders/conditions
- RNA; fine or coarse punctuate granules fairly even distribution
- Lead poisoning, thalassemia
Howell-Jolly bodies
- Composition of inclusions
- Disorders/conditions
- DNA; 1 per cell
- Sickle cell anemia, megaloblastic anemia
Pappenheimer bodies (Wright stain); Siderotic granules (Prussian blue iron stain)
- Composition of inclusions
- Disorders/conditions
- Non-heme iron; fine irregular granules in clusters around periphery of cell
- Sideroblastic anemia, thalassemia
Heinz bodies
- Composition of inclusions
- Disorders/conditions
- Denatured Hb; generally membrane-bound
- Thalassemia, G-6-PD deficiency
Cabot rings
- Composition of inclusions
- Disorders/conditions
- Remnants or mitotic spindle; beads on a string
- Pernicious anemia, lead poisoning
- *Don’t confuse w/ Plasmodium species**
Which RBC inclusion doesn’t stain w/ Wright stain? Which stain should be used?
Heinz bodies; use supravital stain (crystal violet)
4 RBC morphologies that can be artificially created
- Crenation → drying artifact
- Rouleaux → sits on slide too long
- Tear drop → too much pressure when making slide
- Schistocytes → too much pressure
RBC inclusion composed of ferric iron; w/ Prussian blue staining, appear as multiple dark blue irregular granules
Siderotic granules
Cell volume of RBC
RDW
Index calculated to correct for presence of shift/stress retics that may otherwise falsely elevated visual retic count
RPI