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RHS > L14- RBC Pathology I > Flashcards

L14- RBC Pathology I Flashcards

1
Q

define the following:

(1) reticulocytosis
(2) erythroid hyperplasia
(3) pancytopenia

A

1- elevated serum reticulocytes
2- excess precursor cells in bone marrow
3- low RBCs, low WBCs, low platelets

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2
Q

Hb makes up __% of the dry weight of RBCs (include why that is important to lab testing)

A

95%- means there cannot be hyperchromatic RBCs since there really can’t be that much more Hb in RBCs

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3
Q

describe the breakdown of Hb

A

HbA, α2β2, 95%
HbA2, α2δ2, ~2%
HbF, α2γ2, ~2 (may slightly inc during pregnancy)

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4
Q

what are the advantages of the RBC shape

A

Biconcave Disc
=> large SA for Hb-O2 interactions –> reach maximal saturation of Hb
-allows for deformability and passage through small capillaries and splenic sinusoids

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5
Q

Define Anemia, then give the practical evaluation of anemia in a clinical setting

A

Defn: reduction (below normal limits) of total circulating RBC mass

  • in practice it is determined throught [Hb] OR packed cell volume / Hematocrit
  • normal [Hb] = 12-15 g/dL
  • normal Hc = ~45%

Note- [Hb]:Hc is about 1:3

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6
Q

define MCV

A

mean cell volume

-average volume of RBC in femtoliters (10^-15L)

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7
Q

define MCH

A

mean cell hemoglobin

-average Hb content per RBC in picograms

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8
Q

define MCHC

A

mean cell hemoglobin concentration

-average [Hb] in given volume of packed RBCs in g/dL

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9
Q

define RDW

A

red cell distribution width
-coefficient of variation of RBC volume (since older RBCs have dec volume)

-normal ~12.5, it will inc with hemolysis

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10
Q

Give the symptoms of Anemia at different severities

A

Mild: asymptomatic

Moderate (poor O2 supply to tissues): easy fatigability, loss of energy, HAs, fainting/dizziness, SOB, palpitations
(more prominent during exercise)

Severe: angina, CHF, confusion

Note- Sxs are more prominent in rapid onsets; in slow onsets, even severe anemia can be asymptomatic

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11
Q

list the clinical signs of anemia

A
  • pallor
  • nail changes
  • hemic murmurs
  • Inc pulse rate and RR –> inc SV –> high output cardiac failure (if severe enough)
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12
Q

how are anemias classified

A
  • morphological changes of RBCs

- pathophysiological mechanisms causing anemia

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13
Q

what are the morphological classifications of anemia

A

1) Normo-, Hypo-chromic: degree of hemoglobinization (or pinkness of) of RBCs
2) Macro-, Normo-, Micro-cytic: based on RBC size

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14
Q

list the 3 morphological classifications of anemia seen in practice (include blood work results)

A

Microcytic Hypochromic anemias: low intracellular [Hb], low MCV

Normochromic Normocytic anemia: normal intracellular [Hb], normal MCV

Normochromic, Macrocytic anemia: normal intracellular [Hb], high MCV

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15
Q

list the microcytic hypochromic anemias

A
  • Fe deficiency
  • anemia of chronic disease (also in normochromic, normocytic)
  • Pb poisoning
  • thalassemia
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16
Q

list the normochromic normocytic anemias

A
  • acute blood loss
  • hemolytic anemia
  • anemia of chronic disease (also in hypochromic, microcytic)
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17
Q

list the normochromic macrocytic anemias

A
  • cobalamin/B12 deficiency

- folate/B9 deficiency

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18
Q

what are the mechanism classifications of anemia

A

1) Accelerated RBC loss/destruction: blood loss, inc destruction / hemolytic anemia
2) Impaired RBC production: defective stem cell, abnormal RBC proliferation / maturation, bone marrow replacement, others

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19
Q

response of body to blood loss depends on….

A
  • rate of blood loss

- internal v external loss

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20
Q

Anemia due to blood loss is divided into….

A
  • acute bleeding (hemorrhage)

- chronic blood loss (in stool, menses, etc)

21
Q

Anemia due to acute hemorrhage:

  • (1) is the immediate concern
  • (2) type of anemia
  • (3) compensation
A

1- hypovolemia
2- normocytic, normochromatic anemia
3- rise in EPO –> reticulocytosis

22
Q

describe the mechanism of anemia in chronic blood loss (include type of anemia)

A

(note- hypovolemia is not a concern)

  • Fe stores are gradually depleted –> underproduction of RBCs
  • microcytic hypochromatic anemia
23
Q

(1) list the common features of hemolytic anemias

(2) how are hemolytic anemias classified

A

1- shortened RBC life span –> inc EPO / erythropoiesis + accumulation of Hb breakdown products

2:
i) by site, intravascular or extravascular
ii) by cause, intrinsic or extrinsic to RBCs

24
Q

list and provide some examples of the 3 causes Intravascular Hemolysis

A
  • Mechanical Injury: defective cardiac valves, microvascular thrombi, heat
  • Complement Fixation: Ab coated RBCs
  • Infections: intracellular parasites (malaria), microbial toxins (clostridia)
25
Q

Extravascular Hemolysis:

  • caused by defects that will cause (1) by (2) cells in the (3), therefore it is associated with (4) in relation to (3)
  • (5) and (6) are the common mechanisms by which (1) occurs
A

1- RBC destruction
2- phagocytes
3- spleen
4- splenomegaly

5- RBCs rendered less deformable (spherocytosis, sickle cell)
6- RBCs rendered foreign (immune mechanism- Ab coating)

26
Q

Peripheral Blood test results that show evidence of hemolytic anemia

A

normochromic normocytic anemia with polychromasia (bluish tinge) +/- nucleated RBCs

27
Q

Bone Marrow test results that show evidence of hemolytic anemia

A

(not usually done)

erythroid hyperplasia

28
Q

Plasma/Serum test results that show evidence of hemolytic anemia

A
  • elevated unconjugated bilirubin
  • elevated LDH
  • elevated free Hb levels (ntravascular hemolysis

-dec or absent Haptoglobin levels

29
Q

Urine test results that show evidence of hemolytic anemia

A
  • hemosiderinuria

- hemoglobinuria (intravascular hemolysis)

30
Q

Intravascular Hemolysis:

(1) bilirubin levels
(2) haptoglobin levels
(3) hemoglobinuria
(4) hemosiderinura
(5) reticulocyte levels
(6) LDH levels
(7) free Hb levels
(8) splenomegaly
(9) Fe recycling

A 
1- inc
2- absent
3- positive
4- positive
5- inc
6- inc
7- large inc
8- absent
9- minimal
31
Q

Extravascular Hemolysis:

(1) bilirubin levels
(2) haptoglobin levels
(3) hemoglobinuria
(4) hemosiderinura
(5) reticulocyte levels
(6) LDH levels
(7) free Hb levels
(8) splenomegaly
(9) Fe recycling

A 
1- large inc
2- dec
3- negative
4- negative
5- inc
6- inc
7- inc
8- present
9- maximal
32
Q

list the common Intrinsic RBC defects causing hemolytic anemia

A

(usually hereditary)
-Membrane Defect: hereditary spherocytosis

  • Enzyme Defect: G6PD deficiency
  • Hb Defect: sickle cell, thalassemia
  • PNH (paroxysmal nocturnal hemoglobinuria)- ONLY ACQUIRED ONE
33
Q

list the common Extrinsic RBC defects causing hemolytic anemia

A

(usually acquired)
Immune mediated damage: autoimmune, drug-associated, transfusion reaction

Non-immune damage: mechanical trauma, infections, chemicals, hypersplenism

34
Q

Hereditary spherocytosis stems from a defect in (1) in the RBC leading them to have (2) shape and a (3) life span.

  • highest incidences in (4) part of the world
  • usually inherited in (5) pattern
A

1- membrane skeleton
2- spheroid shape –> less deformable
3- 10-20 days

4- northern Europe
5- AD (75% of cases)

35
Q

Hereditary spherocytosis:

  • (1) list affected proteins
  • (2) pathogenesis (hint- 5 steps)
A

1- ankyrin, band 3, spectrin, band 4.2

2- reduced membrane stability –> loss of fragments (normal shearing forces in circulation) –> more spherical RBCs –> cannot transverse splenic sinusoids –> phagocytosis / destruction by splenic macrophages (=> splenomegaly)

36
Q

list the clinical features of Hereditary Spherocytosis (Sxs)

A

Anemia: mild to moderate, 25% asymptomatic, minority are severely anemic from birth

Splenomegaly

Jaundice: unconjugated hyperbilirubinemia (continous hemolysis)

37
Q

_____ along with hereditary spherocytosis can induce aplastic / hemolytic crises

A

parvovirus B19 infection

38
Q

hereditary spherocytosis Tx

A
  • supportive

- splenectomy –> corrects anemia, spherocytosis persists

39
Q

Hereditary Spherocytosis diagnosis and lab findings

A
  • FHx
  • CBC for anemia
  • evidence of hemolysis
  • elevated MCHC
  • positive Osmotic fragility test
  • negative Coombs test

Peripheral blood: normochromic normacytic anemia, spherocytes, polychromatic cells (w/ or w/o nucleated RBCs), Howell-Jolly bodies (post-splenectomy)

40
Q

explain osmotic fragility test

A
  • confirms presence of spherocytes

- spherocytic RBCs lyse prematurely when exposed to inc hypotonic salt solutions

41
Q

explain the coombs test for hereditary spherocytosis

A
  • spherocytes are seen in hereditary spherocytosis and in autoimmune
  • Neg. coombs test confirms hereditary spherocytosis

Test is specifically for autoimmune hemolysis

42
Q

G6PD deficiency is inherited in (1) fashion. List the specific alleles / variants for G6PD, (2).

A

1- X-linked (affects mainly males)

2:

  • G6PD A+, high enzyme levels, no hemolysis
  • G6PD A-, lower enzyme levels, acute intermittent hemolysis
  • G6PD Mediterranean, more severe than other A- variants
  • G6PD B, normal variant
43
Q

G6PD A- variant:

  • normally seen in (1) people
  • characterized by (2)
A

1- 10% of american blacks

2- normal enzyme activity, but dec half-life

44
Q

G6PD Mediterranean variant:

  • normally seen in (1) people
  • (2) is the reason why it may have high persistance
A

1- Middle Eastern populations

2- protects against malaria

45
Q

describe the parameters that allow for the pathogenesis of G6PD deficiency event to occur

A

Parameters:

  • abnormal enzyme are misfolded –> prone to proteolytic degradation
  • enzyme is not made, no nucleus in RBC
  • Note: G6PD A- half-life is moderately reduced, Mediterranean is severely reduced
46
Q

describe the pathogenesis of a G6PD deficiency event

A

1) RBC exposed to oxidants / oxidative stress
2) SH-groups on globin chains of Hb are oxidized
3) precipitation of denatured globins on RBC membrane
4) Heinz body formation

5a) for severe membrane damage –> intravascular hemolysis occurs
5b) less affected RBCs go to spleen –> macrophages ‘bite out’ inclusions => bite cells —> extravascular hemolysis

47
Q

describe the clinical presentation of G6PD deficiency

A
  • Acute Hemolysis: intravascular hemolysis 2-3 days after exposure to infection, drugs (antimalarials, Sulfas), foods (fava beans)
  • Neonatal jaundice, uncommon
  • Chronic low grade anemia, uncommon: lacks known environmental triggers
48
Q

Triggers for G6PD deficiency:

(1) common drugs
(2) common foods

A

1- antimalarials (primaquine), sulfonamides

2- fava beans

49
Q

Diagnosis of lab findings for G6PD deficiency

A
  • clinical Hx
  • CBC w/ anemia + evidence of hemolysis
  • Peripheral blood: normochromic, normocytic anemia, heinze bodies, polychromatic cells (+/- nucleated RBCs), bite cells
  • G6PD enzyme assay (complete during hemolytic episodes, repeat 3 mos. after)

RHS (35 decks)

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