- RBC x 3 = ~ Hb - Hb x 3 = ~ Hct +/- 3

Lab Evaluation of RBCs Flashcards by Liz Haywood

RBC count (manual or automated)
- Basic procedure

Whole blood diluted w/ isotonic diluting fluid and RBCs counted

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RBC count (manual or automated)
- Normal (adult) reference values

4-6 million /mm^3

- NOTE DIFFERENCES B/W MEN AND WOMEN

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Retic count

- Basic procedure

Whole is diluted w/ supravital stain, smears made, retics count–expressed as %

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Retic count

- Normal (adult) reference values

0.5-1.5%

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Hemoglobin

- Basic procedure

Whole blood is diltued w/ reagent containing a lysing agent

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Hemoglobin

- Normal (adult) reference values

Male: 14-18 g/dL
Women: 12-16 g/dL

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Microhematocrit

- Basic procedure

Whole blood spun down 5 minutes in 2 microhematocrit tubes, sealed at one end w/ clay; determined using reader

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Microhematocrit

- Normal (adult) reference values (% of packed cell volume)

Men: 42-54%
Women: 36-48%

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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

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Erythrocyte sedimentation rate (ESR)

- Normal (adult) values

Men: 0-15 mm
Women: 0-20 mm

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Volume factor for all 9 squares on a hematocytometer

1/(1 x 1 x 0.1 x 9) = 1.1

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Volume factor for 4 W corners on a hematocytometer

1/(1 x 1 x 0.1 x 4) = 2.5

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Volume factor for center square on a hematocytometer

1/(1 x 1 x 0.1 x 1) = 10

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Volume factor for manual RBC area on a hematocytometer

1/(0.2 x 0.2 x 0.1 x 5) = 50

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Retic counts

- Type of stain used

Supravital

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Retic counts

- Two retic stains commonly used

New methylene blue

- Brilliant cresyl blue

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Retic counts

- Composition of reticulum

RNA

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Calculate uncorrected retics

(# retics/1000) = (x/100)

- Expressed as a %

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Calculate corrected retics

observed retics x (patient’s Hct/”normal” Hct)

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Calculate RPI

(corrected retic count)/2

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Calculate absolute retic count

(uncorrected retic count x RBC count)/100

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Form of Hb that can’t be measured by cyanmethemoglobin method

Sulfhemoglobin

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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)

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Rule of 3

RBC x 3 = ~ Hb

- Hb x 3 = ~ Hct +/- 3

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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

Lab Evaluation of RBCs Flashcards

Manual RBC Intro to Hemacytometers Retic Counts Manual Hb, Microhematocrits, ESRs, RBC Indices