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Hematology > Hematology Exam 3 > Flashcards

Hematology Exam 3 Flashcards

1
Q

What is the total VOLUME of one side of the hemacytometer? What is the total AREA of one side of the hemacytometer?

A

0.9 mm^3 (volume)
9 mm^2 (area)

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2
Q

How thick is the coverslip placed on top of the hemacytometer?

A

0.1 mm

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3
Q

What is the area of the small “R” squares in a hemacytometer?

A

0.04 mm^2

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4
Q

What is the area of the large “W” squares in a hemacytometer?

A

1 mm^2

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5
Q

What is the calculation for the hemacytometer?

A

Total count (cells/uL) = cells counted x dilution factor / squares counted x area (mm^2) x 0.1

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6
Q

If an average of 96 cells were counted in 4 large squares, what is the total cell count?

A

(20)(96)/(4)(1)(0.1) = 4800 cells/uL

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7
Q

What is the dilution used for manual WBC counts?

A

1:20 dilution

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8
Q

When would you perform a correct WBC count and why? FORMULA FOR THIS WILL BE GIVEN ON EXAM

A

If there is a presence of 5 or more NRBCs a corrected WBC count is needed since NRBCs are not lysed by the diluting fluid, they can falsely increase the WBC count.

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9
Q

The corrected WBC count should always be ______ than the first WBC count.

A

Lower

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10
Q

Which area of a hemacytometer is counted for manual PLT count? What dilution is used?

A

1:100 dilution is used; count the 25 small squares inside of the center large square

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11
Q

Describe the cyanmethemoglobin for determining HGB

A

Blood is diluted in Drabkin’s solution.
Fe2+ Hemoglobin is oxidized to Fe3+ methemoglobin by K ferricyanide found in the solution.
Fe3+ methemoglobin is then converted to Fe3+ cyanmethemoglobin by potassium cyanide found in the solution.
Absorbance of cyanmethemoglobin at 540nm is directly proportional to the hemoglobin concentration.

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12
Q

What is Drabkin’s solution?

A

Used in cyanmethemoglobin method for hemoglobin determination - consists of potassium ferricyanide and potassium cyanide

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13
Q

Hematocrit

A

Volume of pRBCs that occupies a volume of whole blood AKA PCV packed cell volume

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14
Q

Describe the rule of three in hematology. What does it mean if results do not follow this rule?

A

The hematocrit should be 3x the value of hemoglobin (+/- 3). If results do not follow this rule, the patient has abnormal RBCs (hypochromic or microcytic) or there was an error in testing.

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15
Q

Normal range for MCV.
What is the calculation for MCV?

A

Normal: 80-100 fL (<80 = microcytic, >100 = macrocytic)
Calculation: HCT% x 10/RBC count

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16
Q

Normal range for MCH.
What is the calculation for MCH?

A

Normal: 26-32 pg
Calculation: HGB (g/dL) x 10/RBC count

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17
Q

Normal range for MCHC.
What is the calculation for MCHC?

A

Normal: 32-36 g/dL (<32 = hypochromic, >36 = normochromic, spherocytes)
Calculation: HGB (g/dL) x 100/HCT

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18
Q

What is a reticulocyte?

A

Last immature RBC stage

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19
Q

What is the reticulocyte count used for?

A

To assess the erythropoietic activity of the bone marrow

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20
Q

What stain is used for a reticulocyte count

A

New methylene blue

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21
Q

How to identify a reticulocyte during a retic count

A

Two or more particles of blue-stained material (RNA) is observed

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22
Q

How is a manual retic count performed?

A

Count 1000 RBCs under oil and count retics you see. Retic count = Retics/1000 cells counted = Retic %

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23
Q

What do increased reticulocyte counts mean?

A

Could indicate anemia; the bone marrow is trying to release RBCs prematurely to make up for hypoxia

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24
Q

How to use the Miller Disc? What is the purpose?

A

The purpose is to reduce the labor-intensive process of counting 1000 RBCs for reticulocyte counts.
RBCs are counted in the smaller square (B) and reticulocytes are counted in the larger square (A) and should count at least 112 cells in the small square

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25
Q

What is the absolute reticulocyte count? (ARC)

A

The actual number of reticulocytes in 1L of blood; reported in a number instead of %

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26
Q

What is the purpose of the reticulocyte production index? (RPI)

A

Shift reticulocytes were released from the BM to compensate for anemia and will falsely increase the retic count; so RPI is used to calculate a correction factor

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27
Q

What is an ESR

A

The distance in mm the RBCs fall in 1 hour

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28
Q

What is the purpose of the ESR

A

to detect and monitor the course of inflammatory conditions, infections, or malignancies

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29
Q

What factors can elevate ESR?

A

Rouleaux, increased plasma proteins, pregnancy

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30
Q

What factors can decrease ESR?

A

anemia, sickle cell, polycythemia, newborn

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31
Q

What is the purpose of POC testing?

A

Offers ability to provide rapid and accurate results at the patient’s bedside

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32
Q

List 3 hematology POC tests

A

Hematocrit, Hemoglobin, Cell and PLT Counts

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33
Q

What two basic principles of operation do most automated analyzers rely on?

A

Electronic impedance (resistance) and Optical scatter

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34
Q

What is the impedance principle?

A

Based on the detection and measurement of changes in electrical resistance produced by cells as they traverse a small aperture

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35
Q

Coulter’s Principle of Electrical Impedance: What do the number of pulses represent?

A

The number of cells counted

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36
Q

Coulter’s Principle of Electrical Impedance: What does the height of the voltage pulse represent?

A

Volume of the cell

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37
Q

Coulter’s Principle of Electrical Impedance: where is the data plotted?

A

Volume distribution histogram

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38
Q

Coulter’s Principle of Electrical Impedance: What is the X and Y axis on the volume distribution histogram?

A

X axis: volume of each cell
Y axis: number of cells

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39
Q

Coulter’s Principle of Electrical Impedance: What separates the cell populations?

A

Volume thresholds

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40
Q

Coulter’s Principle of Electrical Impedance: What are the three parts WBCs are separated into?

A

Lymphocytes, mononuclear cells (monocytes), and granulocytes (eos, basos, neutros)

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41
Q

BRIEFLY describe radiofrequency and direct current.

A

Cell volume is proportional to the change in direct current, cell interior density is proportional to change in radiofrequency signal. Allows for a five-part differential: neutrophils, lymphs, monos, eosinos, basos

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42
Q

What does forward angle light scatter correlate with? What does side scatter correlate with?

A

Forward angle: (0 degrees) correlates with cell volume
Side scatter: (90 degrees) correlates with cell complexity

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43
Q

Which instrument uses MAPSS to perform its WBC differential?

A

Cell-Dyn

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44
Q

What parameters are affected by Cold agglutinins? Why? How do you correct this?

A

Decreased RBC and Increased MCV and MCHC due to agglutination of RBCs; correct by warming specimen to 37C and rerun

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45
Q

What parameters are affected by Lipemic/icteric specimens? Why? How do you correct this?

A

Increased HGB and MCH due to increased turbidity affecting spectrophotometric reading; correct with plasma replacement

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46
Q

What parameters are affected by hemolytic specimens? Why? How do you correct this?

A

Increased HCT, Decreased RBC due to RBCs lysed and not counted; correct by requesting new specimen

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47
Q

What parameters are affected by PLT clumps? Why? How do you correct this?

A

Decreased PLT, Increased WBC due to large clumps counted as WBCs and not PLTs; correct by redrawing specimen in sodium citrate and multiply result by 1.1

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48
Q

What parameters are affected by old specimens? Why? How do you correct this?

A

Increased MCV, MPV and decreased PLT due to RBCs swelling as specimen ages and PLTs swell and degenerate. Correct this by establishing stability and specimen rejection criteria

49
Q

In what time frame should blood films be made?

A

Within 4 hours of collection

50
Q

What is the most commonly used method for making peripheral blood films?

A

Manual wedge technique

51
Q

How would you adjust the angle of the blood smear for a patient with a high HCT?

A

Lower angle

52
Q

How would you adjust the angle of the blood smear for a patient with a low HCT (anemic)?

A

Higher angle

53
Q

What is in included in Wright-Giemsa stain?

A

Polychrome stains (eosin and methylene blue), giemsa, methylene

54
Q

What is the purpose of methylene in the Wright stain?

A

Fixes cells to the slide

55
Q

What type of stain is eosin? What does it stain?

A

It is an acidic stain that stains basic cell components such as HGB and eosinophilic granules

56
Q

What type of stain is methylene blue? What does it stain?

A

It is a basic stain that stains acidic cellular components such as RNA

57
Q

Why might RBCs appear too gray, WBCs appear too dark, or eosinophil granules appear gray on a blood film?

A

Stain or buffer was too alkaline, inadequate rinsing, prolonged staining, or heparinized blood specimen

58
Q

Why might RBCs appear too pale/red or why might WBCs be barely visible on a blood film?

A

Stain or buffer was too acidic, underbuffering, overrinsing

59
Q

Describe the optimal assessment area for examining a peripheral blood smear.

A

RBCs should be uniformly and singly distributed with few touching or overlapping and have a normal biconcave appearance (~200-250 RBCs per 100x field)

60
Q

SI vs Common units

A

SI = per L
Common = per uL, dL, or %

61
Q

Microcytosis

A

RBCs are smaller than average (low MCV)

62
Q

Macrocytosis

A

RBCs are larger than average (high MCV)

63
Q

Anisocytosis

A

RBCs are unequal in size and have a large variability (large RDW)

64
Q

Hypochromia

A

Larger central pallor (low MCHC)

65
Q

Polychromasia

A

Appearance of blue-gray cells with red cells indicating premature release of RBC from bone marrow

66
Q

Poikilocytosis

A

Increase in abnormally shaped RBC

67
Q

RBC morphology parameters

A

Cell size (microcytosis, macrocytosis)
Variability in size (anisocytosis)
Cell color (polychromasia)
Cell shape (poikilocytosis)
Cellular inclusions (pappenheimer bodies, toxic granulation, etc.)

68
Q

WBC parameters reported in CBC

A

Total WBC count (WBCs x 10^9/L)
WBC differential count (relative)
WBC differential count (absolute)
WBC morphology

69
Q

PLT parameters reported in CBC

A

PLT count (PLTs x 10^9/L)
Morphology
MPV (mean platelet volume)

70
Q

RBC parameters reported in CBC

A

RBC count (RBCs x 10^12/L)
HGB (g/dL)
HCT (%)
MCV
MCH
MCHC
RDW
Morphology

71
Q

A hypochromic, microcytic anemia would have abnormal results for which two main RBC parameters?

A

Low MCV
Low MCHC

72
Q

What RBC parameter is anisocytosis associated with?

A

Large RDW

73
Q

What RBC parameter is macrocytic associated with?

A

MCV (high)

74
Q

What RBC parameter is hypochromic associated with?

A

MCHC (low)

75
Q

What are the main reasons flow cytometry testing is performed?

A

To detect/monitor leukemias, lymphomas, and HIV

76
Q

What are the proper storage requirements for flow cytometry specimens (blood, bone marrow, fluids, tissues)

A

Blood and BM: Room temp less than 24hrs
Fluids and Tissue: Refrigerated 4C less than 24hrs

77
Q

Monoclonal antibodies in flow cytometry

A

Antibodies made from one type of cell

78
Q

CDs in flow cytometry

A

Clusters of differentiation - cluster of antibodies recognizing the same antigen

79
Q

BRIEFLY describe how a flow cytometer works

A

uses hydrodynamic focusing and lasers as light sources to produce both scattered and fluorescent light signals that are read by detectors, signals are converted into electronic signals that are analyzed by a computer

80
Q

What is gating in flow cytometry?

A

Selection of a population of interest as defined by one or more flow cytometric parameters

81
Q

What cells show the highest density of CD45 in flow cytometry?

A

Lymphocytes, then monocytes

82
Q

What cells show intermediate CD45 density?

A

Granulocytes

83
Q

What cells are negative for CD45?

A

Late erythroid precursors and megakaryocytes

84
Q

What cells are the most complex (most side scatter)?

A

Granulocytes

85
Q

What cells are the least complex (not much side scatter)

A

Lymphocytes

86
Q

What cells are biggest (most forward scatter)

A

Monocytes

87
Q

What CD markers are present on megakaryoblasts?

A

CD31 and CD36

88
Q

What CD markers are the first of megakaryocytic differentiation?

A

CD41 and CD61

89
Q

What are blasts characterized by?

A

Low density expression of CD45

90
Q

What is the CD4:CD8 ratio in healthy individuals?

A

> 1 (more CD4)

91
Q

What is the CD4:CD8 ratio in HIV positive patients?

A

<1 (losing CD4)

92
Q

How is flow cytometry used to monitor HIV therapy?

A

CD4 and CD8 antibodies used to measure CD4:CD8 ratio

93
Q

What RBC, granulocyte, and monocyte CD markers are decreased in PNH?

A

RBC: CD55 and CD59
Granulocyte: CD24 and FLAER
Monocyte: CD14 and FLAER

94
Q

List the purines

A

Adenine and Guanine

95
Q

List the pyrimidines

A

Thymine, Cytosine, and Uracil

96
Q

In DNA, A pairs with?

A

T

97
Q

In RNA, A pairs with?

A

U

98
Q

In DNA, G pairs with?

A

C

99
Q

Why is isolation of RNA more difficult than DNA?

A

There is RNases present on the surface of human skin which can lead to contamination of lab surfaces and inhibition of amplification

100
Q

Regular PCR vs RT-PCR

A

Regular PCR amplifies DNA, RT-PCR amplifies RNA

101
Q

Process/Purpose of PCR

A

Denaturation of DNA, DNA polymerase binds to DNA and reads template and amplicon is reproduced millions of times to detect viruses/bacteria genomes

102
Q

What is gel electrophoresis

A

Separation of DNA fragments by their MASS only

103
Q

Agarose gel vs polyacrylamide gel

A

Agarose gel has larger pores and allows for larger fragments to pass
Polyacrylamide gel has smaller pores and is more effective for smaller fragments

104
Q

Anode vs cathode

A

Anode is the positively charged electrode; Cathode is the negatively charged electrode

105
Q

How do fragments move in electrophoresis and why

A

Since DNA is negatively charged, it moves towards the positively charged anode

106
Q

What fragments move further in gel electrophoresis?

A

Smaller fragments will move faster and at a further distance

107
Q

How does capillary gel electrophoresis differ from regular gel electrophoresis?

A

Capillary gel electrophoresis is automated and separation is rapid and has greater resolution with more accuracy

108
Q

In one sentence, describe the theory behind RFLP (Restriction Fragment Length Polymorphism)

A

If there is a mutation present, restriction endonucleases will not cleave the same sites, and will produce restriction fragments of different lengths than normal.

109
Q

Describe real-time PCR Ct/Cp

A

Ct is cycle threshold and this is the PCR cycle at which amplification crosses the threshold; it is inversely related to the amount of target; the more starting DNA that is present, the lower the number of PCR cycles required to amplify.

110
Q

Describe qualitative vs quantitative real-time PCR

A

Qualitative PCR is looking for the presence or absence of a mutation while quantitative PCR is looking for the amount of copies of the mutation present

111
Q

What types of body fluids can be tested in the hematology lab?

A
  • CSF
  • Serous/body cavity fluid (pleural, pericardial, peritoneal fluids)
  • Synovial (joint)
  • Bronchoalveolar lavage (BAL)
112
Q

Describe ependymal/choroid plexus cells. Which body fluid can they be found in?

A

They can be found in CSF because they line the CNS, and they are clumps of basophillic cells with round nuclei

113
Q

Describe cartilage cells. Which body fluid can they be found in?

A

These are seen in CSF if vertebral body is accidentally punctured - they are a deep wine-red color.

114
Q

Describe siderophages. Which body fluid can they be found in?

A

These can be found in CSF and they are macrophages that have ingested RBCs and as a result of the breakdown of RBCs contain hemosiderin and sometimes bilirubin.
Bilirubin = yellow crystals
Hemosiderin = large dark blue/black granules in cytoplasm

115
Q

Describe mesothelial cells. Which body fluid can they be found in?

A

They can be found in serous fluids (like pleural fluid). They have a fried egg appearance and may be multinucleated.

116
Q

Describe LE cells. Which body fluid can they be found in?

A

Lupus erythematosus cells may be seen in serous fluids of patients with lupus (SLE). They are intact neutrophils that have engulfed nuclear material, which displaces the normal nucleus.

117
Q

Describe signet ring cells. Which body fluid can they be found in?

A

Signet ring cells are macrophages that have ingested lipids and can be found in serous fluids. They are a clear-like cell with a purple border and the nucleus on one far edge of the cell.

118
Q

Describe ciliated epithelial cells. Which body fluid can they be found in?

A

These are normally found in BAL specimens and should be reported because they indicate that the sample was taken from the URT instead of deeper in the lung. They are columnar cells with the nucleus at one end of the cell and cilia at the opposite end of the nucleus.

119
Q

What are the most common cells seen in a BAL?

A

Neutrophils, monohistiocytes (macrophages), lymphocytes

Hematology (10 decks)

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