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CMOD-Block 2 Path > Strom CBC > Flashcards

Strom CBC Flashcards

1
Q

What 4 methods are used to obtain a CBC?

A
  1. Manual Methods
  2. Spectrophotometry
  3. Conductivity (Coulter Method)
  4. Flow Cytometry
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2
Q

By what method is hemoglobin measured?

  • what is done to the RBCs so that this can be measured?
  • what color is the light?
  • why is this important?
A

SPECTROPHOTOMETRY

  • Red cells are lysed and Cyanide is added
  • light is blue
  • If you eat a fatty meal you Hgb will appear artificially high
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3
Q

If you have a centrifuged tube of blood sitting in front of you with RBCs on bottom and Plasma on top, how do you calculate Hematocrit?

A

(Packed Volume of Red Cells)/(Total blood Volume) = %

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4
Q

Differentiate between a vial with a Lavender top, Blue top, and Green top. Why would you use any of these?

A

These all contain Anti-coagulants or Chelating agents (lavender and blue) to pull Ca2+ out of the blood and prevent it from clotting

Lavender Top - EDTA
Blue Top - Citrate
Green Top - Heparin

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5
Q

If someone tells you they took a “spin hematocrit” what did they use to measure hematocrit?

A

Capillary Tube

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6
Q

How is a Red blood Cell count obtained?

A

Coulter Chamber (counter)

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7
Q

How does a Coulter Counter Work for a Red Blood Cell count?

A

Smaller container with a small hole about the size of a blood cell is pumped RBCs through one at a time, resistance changes as this happens and the counter counts a single blood cell

**Note: every kind of cell RBC and WBC is counted but this doesn’t make a difference because 99% of cells are RBCs

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8
Q

What does a manual leukocyte differential measure that an automated one doesn’t?

A

Manual Measures:
Bands
Metamyelocytes

**But not always, you can’t just tell from looking if it was a manual count, you typically have to request these

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9
Q

What automated method is used to measure leukocytes?

A

Coulter Counter is used and RBCs are lysed while WBCs are left in tact you can then use the same

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10
Q

What formula do you use to obtain hematocrit?

A

Volume x (# of cells)

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11
Q

How would hemoglobin appear in an anemic patient whose cells were lysing in their blood stream?
- how would you pick up on this?

A
  • Hbg would appear normal even though its not

**This is because all RBCs are lysed in spectrophotometry (the method used to measure hematocrit) so you don’t know if they were lysed in the body or not

PICK UP ON THIS BY SEEING A DISCREPANCY BTWN HEMATOCRIT AND HEMOGLOBIN (Hct will be lower than 3x Hbg)

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12
Q

What is the problem with eosinophils and basophils in the CBC?
- how is this problem solved?

A

They are not well separated from the other leukocyte population

  • FLOW CYTOMETRY is performed on the cells as they emerge from the Coulter counter, and SIDE SCATTER is measured, this solves this problem
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13
Q

What does side scatter in flow cytometry measure exactly?

A

Measures the cytoplasmic granules within the cells

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14
Q
  • *How can we measure the amount of reticulocytes (immature blood cells) in the blood?
  • Why is this so important, yet underutilized?
A

Use Nucleic acid fluorescent dyes on RBCs and send them through
**Reticulocytes will be more fluorescent than RBCs

  • This is super important because if we have an Anemic Patient we can start to trace the source, we can tell if they Anemic Because they aren’t making RBCs or because they’re losing RBCs
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15
Q

How are bands and most other immature granulocytes counted in most automatic analyzers?

A

All counted as neutrophils

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16
Q

How are blasts counted in most automatic analyzers?

A

As Lymphocytes or Monocytes

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17
Q

If Red blood cell fragements are detected in an automatic analyzer, how will they be counted?

A

Probably as Platelets

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18
Q

What is the problem with platelet clumps in the analyzer?

A

They aren’t always detected and may show up as a thrombocytopenia

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19
Q

If a lab caught on that the automatic analyzer had missed platelet clumps, what might they request?

A
  • They’ll want you to send a sample in citrate (blue top) instead of EDTA (lavender top)

**THIS SHOULD BE IN YOUR DDx for Thrombocytopenia

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20
Q

By counting blasts as lymphocytes, what might your automated blood counter be missing?

A

An acute leukemia may no be flagged

  • Microscopy is needed to determine this
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21
Q

A patient has a WBC of 15.4 and you suspect pneumonia, what should you do next?

A

Ask for a manual count to determine:

  1. Bands - left shift
  2. Metamyelocytes - Further to the left than bands
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22
Q

How often would you ever see a pluripotent stem cell in the bone marrow?
- would you know what is was if you did see it?

A
  • less than 1 in 20 million cells = Pluripotent Stem Cell

Hard to Identify because they look just like other blasts:

  • Hypodense Chromatin
  • No features of a Differentiated Cell
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23
Q

Burst Forming units (BFU) and Colony Forming Units (CFU) are currently defined by their responsivness to a handful of key known growth factors

A

Burst Forming units (BFU) and Colony Forming Units (CFU) are currently defined by their responsivness to a handful of key known growth factors

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24
Q

What factor stimulates Red Blood Cell formation?

A

EPO

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25
Q

What factor stimulates Megakaryocyte formation?

A

TPO

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26
Q

What factor Stimulates the formation of neutrophils only?

A

G-CSF

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27
Q

What factor stimulates the formation of Monocytes, Neutrophils, and Eosinophils?

A

GM-CSF

28
Q

How many cells in normal bone marrow should be doing each of the following:

  • Erythropoiesis
  • Myelopoiesis
  • Lymphoiesis
A
  • Erythropoiesis (20-30%)
  • Myelopoiesis (60-70%)
  • Lymphoiesis (10-20%)
29
Q

What percentage of your marrow should be blasts?

A

Less than 4%

30
Q

What are the neutrophil precursors seen at each phase in neutrophil formation?

  • what percentage of each should be in the marrow?
  • What growth factors regulate this differentiation?
A

GM-CSF and G-CSF

Blast (3-4%)
Promyelocyte (2-8%)
Myelocyte (10-13%)
Metamyelocyte (10-15%) 
Bands and Neutrophils (25-40%)
31
Q

Of the 5 cell types that are formed on the way to making neutrophils, what is the last cell type that can divide?

A

Myelocyte - after this point it is committed to becoming a neutrophil

32
Q

What cells does GM-CSF act on?

- what cells release GM-CSF?

A

Bone Marrow Stromal Cells release GM-CSF

Promyelocytes (2-8%)
Myelocytes (10-13%)
Metamyelocytes (10-15%)

33
Q

What cells does G-CSF act on?

- what cells release G-CSF?

A

G-CSF released by Bone Marrow Stromal cell and acts on:

Myelocytes (10-13%)
Metamyelocytes (10-15%)

34
Q

What cells secrete EPO?

- what does EPO act on?

A

EPO secreted by renal peritubular cells

EPO acts on:

  • Pronormoblast
  • Basophilic Erythroblast
  • Polychromatophilc Erythroblast
35
Q

When do the renal peritubular cells send out EPO?

A

During Hypoxic conditions

**Consider Renal Peritubular Cell dysfunction in your differential for unexplained anemia

36
Q

What cells can be looked at from aspirated material and which are looked at by “core biopsy” material?

A
  • Neutrophils and their precursors as well as Red cells and their precursors are seen in aspirated material
  • Platelets and their precursors are seen in Core Biopsy Material
37
Q

How are platelets made?

A
  • Matue Megakaryocytes send out small tubes of themself into blood vessel fenestrations within the bone marrow (aka sinus)
  • Mature platelets then get chopped off one at a time
38
Q

What growth factor drives the formation of platelets?

- where does it come from?

A
  • TPO

- Excreted at a constant rate from hepatocytes

39
Q

How does TPO work (or how do they think it works)?

A
  • TPO is secreted from the liver at a constant rate
  • It binds to both platelets and megakaryocytes
  • If more platelets are in the blood, then TPO will be soaked up by platelets and Megakaryocytes won’t be stimulated for platelet production (this is good)
  • If Few platelets are in the blood then most TPO will get taken up by Megakaryocytes and More Platelets will be made
40
Q

What are the key players in Porphyrin Synthesis?

- Enzymes/Co-factors/Subrates?

A

Enzymes:
ALA synthetase
Ferrochelatase

Co-Factors/Substrates:
B6
Succinyl CoA
Glycine

41
Q

What enzyme defect results in Erythropoietic Protophorphyria?
- what is the result of a defect in this enzyme?

A
  • Ferrochelatase

- Sideroblasts are formed by overloaded iron transport into the Mitochondria

42
Q

What is the result of Porphobilinogen being high in the blood as a result of a heme synthesis defect?

A

Sun exposed skin easily gets damaged and nervous tissue does too

43
Q

What effect does lead poisoning have on the appearance of RBCs?

A

Large Basophilic Stippling can be see when they’re stained

44
Q

What form does iron need to be in for us to absorb it in the G.I. tract?

  • what enzyme is responsible for getting it into this form?
  • Co-Factors ?
  • What will happen if any one of these components is missing?
A

Duodenal Reductase
- Reduces Iron from Fe3+ (Ferric, can’t be absorbed) to Iron Fe2+ (ferrous, can be absorbed)

  • Abscorbate Donates electron to Fe3+
  • Low Abscorbate, Low Iron, or Deficient enzyme will lead to Anemia
45
Q

What iron transporter is located on the apical and basolateral sides of enterocytes?

  • Are both of the proteins always expressed?
  • If not then explain.
A

Apical Side:

  • DMT-1
  • Translation of DMT-1 depends on Iron so it is only synthesized when iron is abundant

Basolateral side:

  • Ferroportin
  • Upregulated in high iron, but no iron dependent translation
46
Q

What happens to iron once is crosses through DMT-1 and Ferroportin to enter the plasma?

A
  1. Ferrous iron (Fe2+) oxidized to Ferric iron (Fe3+) by serum oxidases
  2. Fe3+ binds to serum transferrin to make Fe3+/Transferrin and it travels around to get deposited in tissues
47
Q

What is the point of using transferrin to transport serum iron?

A
  • It prevents Bacterial Growth, since they are very heavily dependent on iron
  • Prevents the formation of ROS via the Fenton Reaction
48
Q

Where does iron typically go when it exits the plasma?

  • Storage?
  • Use?
A

Storage:
- Macrophages in the Liver, Spleen, and Bone Marrow

Use:
- Red Cell precursors in the Bone marrow

49
Q

What is Hepacidin?

  • where does it come from?
  • what does it do?
  • what does it mean when its high?
  • what does it mean when its low?
A

Hepacidin

  • Released by the liver
  • Down Regulates the amount of Ferroportin expressed on the cells of organs

Hepacidin High:
- Ferroportin on macrophages will be down regulated and serum [Fe] will drop

Hepacidin Low:
- Ferroportin on macrophages will up regulated and [Fe] will rise in serum

50
Q

What happens if your liver makes:

  • too much Hepacidin?
  • too little Hepacidin?
A

Too Much:

  • Ferroportin will be down regulated
  • You will get anemic because serum iron will drop and all iron will be trapped in macrophages in the liver, spleen, and bone marrow

Too Little:

  • Ferroportin will be up regulated
  • You get iron deposition in inappropriate tissues that is driven by [Fe] in serum being too high
51
Q

What two genes is normal globin sythesis dependent on?

A
  • Alpha and Beta globin genes
52
Q

T or F: While Red Blood Cells have not nucleus, at one point they had a large nucleus and needed lots of DNA

A

True

53
Q

What enzyme/co-factors are needed for DNA synthesis?

A

Enzyme:

  • Ribonucleotide Reductase
  • Thymidine

Co-Factors:

  • B12
  • Folate
54
Q

What amino acids are needed in purine synthesis?

  • other things?
  • what nucleotides are the purines?
A
  • Gln
  • Glu
  • Asp

**PRPP needed too

*A and G = purines

55
Q

What version of Tetrahydrofolate (THF) is needed to synthesize purine?
- Co-factors/Co-reactants needed to convert from THF to this active methyl donor form?

A

N10-formyl-THF

Cofactors:

  • NADPH
  • CO2
56
Q

What version of THF is needed to make Thymidine?

  • What version of Folate is used to make this?
  • what enzyme is important in this reaction?
  • Co-factor(s)?
A

N5, N10-methylene THF

Made from:
DHF that is converted to THF by DIHYDROFOLATE REDUCTASE

NADPH is the hydride donor

57
Q

How is N5-methyl THF converted back to THF?

  • What accepts this methyl group?
  • Co-factor(s) needed?
  • what happens if this co-factor is missing?
A

Homocysteine accepts the Methyl form N5-methyl THF to become Methionine

  • This requires B12 as a co-factor

***NO B12, then Homocysteine builds up in the blood and the methyl is “trapped” on N5-methyl-THF

58
Q

What should you do if you test for a B12 deficiency and the test comes back negative, but you strongly believe the patient is Anemic because they are deficient in B12?

A

Test for Homocysteine since it builds up without B12 present

59
Q

Other than anemia, what is the problem with having a B12 deficiency?

A

Homocysteine can’t get converted to methionine

  • Methionine is important to sphingomyelin synthesis
  • No sphingomyelin then you get demyelination of the spinal cord and mutiple organ dysfunction
60
Q

Why would kidney failure lead to RBC insufficiency?

A

EPO is made by the kidney’s

  • No EPO no RBC formation in marrow
61
Q

What happens when your marrow gets filled with myelofibroblasts?

A

This is a change in the bone marrow microenvironment causing RBCs not to be formed (anemia)

62
Q

What kind of receptor do EPO and TPO signal through?

A

Jak-2 kinase

63
Q

How do we measure Serum Iron (aka Transport system)?

A
  1. Measure Fe3+/Transferrin in serum
  2. Measure TIBC (total iron binding capacity) - determines if iron is bound to transferrin
    * *this is important because transferrin production is often kicked into high geer when iron availability is low
64
Q

What do we get an estimate of by measuring Serum Ferritin?

A
  • Storage Pool of Iron

Ferritin is found INSIDE of iron storage cells, but SOME leaks out into the serum
*The amount that leaks out is proportional to storage iron

65
Q

T or F: Serum Ferritin is the most useful test you can use as a starting point for unexplained anemias

A

True, It tells you if the Iron is getting to the tissue (if it is then you expect high serum ferritin), or if its not getting to the tissue (low serum ferritin)

66
Q

What if BOTH serum ferritin and Fe3+/Transferrin is low ?

A

You can assume that iron is not getting from the GI tract into the serum in the first place (Duodenal Reductase issue/ DMT-1 / Ferroportin issue) or that iron isn’t getting converted back to Fe3+ in the serum (serum oxidase issue)

CMOD-Block 2 Path (22 decks)

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