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HemOnc Week 1 > Erythrocyte Lab Tests: Topic 1 > Flashcards

Erythrocyte Lab Tests: Topic 1 Flashcards

1
Q

what does CBC stand for?

A

complete blood count

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2
Q

what are CBCs used to determine?

A
  1. determine the status of our overall health
  2. diagnose medical conditions
  3. monitor medical conditions and treatments
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3
Q

what does CBC measure?

A

measures three main cell types within our blood

  1. red blood cells (RBCs)
  2. white blood cells (WBCs)
  3. platelets, which technically are cell fragments
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4
Q

what are the main components of the CBC?

A
  • red blood cell count
  • white blood cell count
  • platelet count
  • hemoglobin
  • hematocrit

all of them: RBC count, hemoglobin, hematocrit, MCV, MCH, MCHC, RDW, WBC count, WBC differential, platelet count, and MPV

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5
Q

what components of the CBC give us the big picture status of our RBCs?

A

red blood count, hemoglobin and hematocrit

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6
Q

what is the RBC count?

A

the number of red cells given as an absolute number per liter

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7
Q

what does the RBC count effect?

A

can directly affect the amount of oxygen our tissues receive because RBCs contain hemoglobin which is what carries oxygen to our tissues and participates in gas exchange

From the results of a RBC count, the physician can determine if our values are higher or lower than normal, which indicates erythrocytosis or anemia, respectively.

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8
Q

what is erythrocytosis?

A

RBC count is higher than normal

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9
Q

what is anemia? how can you tell if someone has anemia from a CBC?

A

RBC count is lower than normal

can be determined by low RBC count, hemoglobin and hematocrit on CBC

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10
Q

what is hematocrit?

A

also known as the packed cell volume (PCV)

it’s the ratio of the volume of RBCs to the total volume of blood

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11
Q

what are the units of hemoglobin on a lab report?

A

grams/dL

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12
Q

what are the types of erythrocytosis?

A
  1. relative: an increase in RBC number without an increase in total RBC mass, usually due to loss in plasma volume
  2. absolute: an increase RBC numbers because of increased RBC mass
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13
Q

what is the mean corpuscular hemoglobin?

A

MCH

the average weight of hemoglobin per RBC

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14
Q

what is the mean corpuscular hemoglobin concentration?

A

MCHC

average concentration of hemoglobin per RBC

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15
Q

what is leukopenia?

A

low WBC count

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16
Q

when can leukopenia happen?

A

drug reactions, autoimmune disorders, cancer, and bone marrow disorders

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17
Q

what is leukocytosis?

A

high WBC count

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18
Q

when can leukocytosis happen?

A

drug reactions and leukemia

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19
Q

what is a WBC differential count?

A

tells us the amount of each type of white blood cell in the body

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20
Q

what is thrombocytosis?

A

too many platelets

can lead to excessive clot formation

21
Q

what is thrombocytopenia?

A

too few platelets

can lead to increased bleeding

22
Q

what is the mean platelet volume?

A

MPV

measures the average volume of platelets

23
Q

what are the three followup tests if there’s an RBC abnormality on the CBC?

A

hemoglobin electrophoresis, osmotic fragility testing, and the direct antiglobulin test

24
Q

what is hemoglobin electrophoresis?

A

gives us an in-depth look at the amount and type of hemoglobin within our RBC

If we apply electrical charge to a gel that contains hemoglobin samples, different hemoglobin types migrate away from the negatively charged electrode, landing at various distances away from their point of origin

+ “A Fat Santa Clause” -

A: normal Hb B chain
F: normal Hb γ chain
S: sickle cell Hb B chain
C: hemoglobin C B chain

25
Q

what are the types of hemoglobin that show up on a Hb electrophoresis?

A

A: normal Hb B chain (HbA adult)

F: normal Hb γ chain (HbF, fetal)

S: sickle cell Hb B chain (HbS)

C: hemoglobin C B chain (HbC)

26
Q

what conditions can hemoglobin electrophoresis help identify?

A

thalassemia, sickle cell disease, sickle cell trait, and hemoglobin C disease

27
Q

what causes thalassemia?

A

caused by decreased production of either alpha or beta globin chains

degree of impairment and severity varies according to the specific genetic mutation that is present, and the number of genes that are affected

28
Q

what is sickle cell disease?

A

a mutation in the beta chain gene causes hemoglobin to polymerize when it deoxygenates, turning the normal biconcave-disc-shaped of RBCs into a crescent moon, or sickle, shape

these sickled cells can get stuck in blood vessels, impairing oxygen delivery to tissues and causing pain and other problems in organs, muscles, and bones

29
Q

what does osmotic fragility testing tell us?

A

tells us how easily our RBCs burst open when they are exposed to solutions of varying salt concentration

30
Q

how do you conduct osmotic fragility testing?

A

the patient’s blood is added to various saline solutions with progressive concentrations of NaCl

the amount of cell lysis (hemolysis) is plotted against NaCl concentration

if the RBCs lyse when the solution is not very hypotonic then they are considered fragile

31
Q

when would a cell undergo hemolysis during osmotic fragility testing?

A

if a cell is placed in a hypotonic solution, water will enter the cell (because the cell has more solute than the surrounding solution), causing swelling of the cell and, eventually, lysis

as the concentration of NaCl in the saline solution increases, the lysis of the RBCs will decrease

32
Q

what is hereditary spherocytosis?

A

A disease process frequently associated with increased osmotic fragility = RBCs lyse when the solution is not very hypotonic

The spherocytes in hereditary spherocytosis are less flexible than normal RBCs, due to cytoskeleton mutations; this makes them more prone to rupture

they’re so sensitive to blood tonicity that they even lyse at higher than normal concentrations of NaCl

33
Q

what disease is associated with increased osmotic fragility?

A

hereditary spherocytosis

34
Q

what diseases are associated with decreased osmotic fragility?

A

sickle cell anemia and thalassemia

35
Q

what does the direct antiglobulin test tell us?

A

DAT aka Coombs test

tells us whether the patient’s RBCs have been coated with antibody or complement (a phenomenon which happens in autoimmune hemolytic anemias and in other clinical settings)

36
Q

how does the DAT test work?

A

anti-Ig antibody (or Coombs reagent) is added to the patient’s RBCs

Coombs reagent is actually a combination of immunoglobulins directed against both human antibodies and complement

If the patient’s RBCs are coated with immunoglobulin (or complement), they will agglutinate, and the test will be considered positive

37
Q

what conditions cause a positive DAT test?

A

A positive DAT may be seen in autoimmune hemolytic anemia, hemolytic transfusion reactions, hemolytic disease of the fetus and newborn, and drug- induced immune hemolysis

aka the patients RBC are coated with immunoglobulin

38
Q

what is autoimmune hemolytic anemia?

A

the body makes antibodies that bind to RBCs, causing them to lyse and making them susceptible to phagocytosis by splenic macrophages.

you will get a positive DAT test for people with AIHA

39
Q

what is differential staining?

A

a process which uses two or more dyes that stain some structures one color and others a different color, allowing you to visualize different structures more easily

Using more than one stain can help the viewer better differentiate between organisms and cellular components

The differential staining of blood cells allows the different types of WBCs to be visualized.

40
Q

what is the wright-giemsa stain?

A

the most commonly-used differential stain for blood specimens

consists of a combination of eosin, which stains cellular structures red, and methylene blue, which stains cellular structures blue

41
Q

what color do negatively charged compounds stain with the wright-giemsa stain? what are examples of negatively charged compounds? what are they called?

A

negatively charged compounds stain with methylene blue and are called “basophilic”

ex. DNA and RNA

42
Q

what color do positively charged compounds stain with the wright-giemsa stain? what are examples of positively charged compounds? what are they called?

A

positively charged compounds stain red and are called “eosinophilic”

ex. hemoglobin

43
Q

what are two types of stains?

A
  1. wright-giemsa stain

2. supravital stain

44
Q

what are supravital stains used for?

A

commonly used to detect reticulocytes (immature RBCs)

A drop of blood is stained with new methylene blue or brilliant cresyl blue, and the ribosomal rRNA in reticulocytes stains a deep blue color, making the reticulocytes easy to visualize

ribosomal rRNA is what’s visible!!!

45
Q

what is the reticulocyte count in anemia?

A

reticulocyte = immature RBC

Counting the number of reticulocytes can provide insight on bone marrow activity and disorders such as anemia

In anemia, the reticulocyte count is often increased because the bone marrow is producing more RBCs to make up for the ones that are lost

46
Q

what is the mean corpuscular volume?

A

MCV

mean RBC size

47
Q

what is the red cell distribution width?

A

RDW

the standard deviation of size from the mean

the higher the RDW, the larger the range of red blood cell sizes

48
Q

what two indices tell us about the size of RBCs?

A

MCV and RDW

mean corpuscular volume: mean RBC size

red cell distribution width: the standard deviation of size from the mean

HemOnc Week 1 (32 decks)

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