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Pathology > Red Blood Cell disorders > Flashcards

Red Blood Cell disorders Flashcards

1
Q

is defined as a reduction in red cell mass, with consequent decrease in oxygen transport capacity of the blood.

A

Anemia

Impaired tissue oxygenation leads to shortness of breath, weakness, fatigue, and pallor

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2
Q

What are three mechanisms by which red cell mass is decreased?

A

RBC (blood) loss - hemorrhage (acute or chronic)
Decreased RBC survival - hemolysis
Decreased RBC production - nutritional deficiencies, aplastic anemia, myelophthistic processes

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3
Q

___ denotes an increase in red cell mass.

A

Polycythemia

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4
Q

List some of the laboratory tests for anemia.

A

CBC (RBC count, Hemoglobin, Hematocrit, Mean cell volume (MCV), Hb (MCH), Hb concentration (MCHC)
WBC, Platelets)
Blood smear review
Reticulocyte count
Iron Indices (serum Fe, iron-binding capacity, transferrin saturation, ferritin concentration and Vitamin B12 and folate (serum and RBC concentrations))
Hemolysis work-up (Bilirubin-
direct and indirect, Haptoglobin, LDH, Coomb’s test, Plasma hemoglobin, Hemoglobin electrophoresis)

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5
Q

Young healthy subjects can tolerate rapid blood loss of 500-___mL (up to 15-20% of total blood volume) with few symptoms, but some will have a ___ response- sweating, weakness, nausea, slow heart rate, hypotension. If blood loss is controlled, ___ fluid will redistribute (within 24 hours) into the vascular space in an attempt to re-expand the vascular volume.

A

1000; vasovagal; interstitial

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6
Q

Rapid blood loss of 2000-2500 mL produces ___.

A

shock

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7
Q

___ blood loss causes anemia when the rate of loss exceeds the capacity for RBC ___ or when ___ reserves are depleted.

A

Chronic; regeneration; iron

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8
Q

What are two important causes of iron deficiency?

A

Chronic GI hemorrhage due to ulcer or neoplasm, or GYN hemorrhage (menorrhagia)

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9
Q

When does intravascular and extravascular hemolysis occur?

A

Intravascular - destruction of red cells within the circulation
Extravascular - destruction of red cells in reticuloendothelial systems (spleen, liver)

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10
Q

With intravascular hemolysis, what conditions are considered immune and non-immune?

A

immune - transfusion reaction

non-immune - mechanical trauma (defective heart valve)

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11
Q

Hemoglobin released from RBC into circulation (hemoglobinemia) is bound to ___, a binding protein, and cleared from the circulation by the liver. A decrease in this serum protein is a key feature of ___ hemolysis.

A

haptoglobin; intravascular

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12
Q

What happens when plasma hemoglobin levels exceed amount of available haptoglobin in intravascular hemolysis?

A

free hemoglobin is excreted in the urine (hemoglobinuria); however hemoglobin is toxic to the kidney, and iron that accumulates in proximal tubular cells in the kidney as a breakdown product of hemoglobin is lost in the urine when these cells are shed (hemosiderinuria).

Conversion of heme (derived from hemoglobin) to bilirubin leads to hyperbilirubinemia and jaundice. The degree of jaundice is dependent on the functional capacity of the liver and rate of hemolysis. Levels of haptoglobin are characteristically low.

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13
Q

Which of the following are immune (extrinsic) and non-immune (intrinsic) examples of extravascular hemolysis:

  1. Autoimmune
  2. Hereditary spherocytosis
  3. Sickle cell anemia
  4. Erythroblastosis fetalis
  5. Transfusion reaction
  6. Thalassemia
  7. Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency
A

Immune (extrinsic) - 1, 4, 5

Non-immune (intrinsic) - 2, 3, 6, 7

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14
Q

How does extravascular hemolysis lead to the formation of gallstones?

A

Damaged or abnormal RBC are removed in spleen, where hemoglobin is broken down intracellularly. Free hemoglobin is not released directly into the blood and urine, but hemoglobin breakdown products are increased (hyperbilirubinemia) and jaundice may result. Spleen and liver may become enlarged since these are sites of removal of RBC from the circulation. Chronically elevated levels of bilirubin can promote formation of gallstones.

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15
Q

In hereditary spherocytosis, there is an inherited (usually autosomal ___) defect in the structural cytoskeleton protein, ___. RBCs are less ___ are are sequestered and destroyed in the ___ because they can’t squeeze through the splenic sinusoids.

A

dominant; spectrin; deformable; spleen

The specific defect can be a qualitative or quantitative deficiency of spectrin

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16
Q

T/F. Splenectomy helps symptoms and anemia of patients with hereditary spherocytosis, but the RBCs remain abnormal.

A

True.

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17
Q

What is the red cell morphology name given in hereditary spherocytosis?

A

spherocyte

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18
Q

Sickle cell anemia is an inherited defect (autosomal ___) in the structure of ___ chain causes hemoglobin to gel upon deoxygenation. The specific defect is a single base pair substitution in DNA that causes a single amino acid substitution (___ for ___) at position ___ in the ___ chain of globin to produce sickle hemoglobin (HbS).

A

codominant; globin; valine; glutamic acid; 6; beta

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19
Q

What induces hemoglobin S polymerization and a “sickled” cell shape?

A

low oxygen tension

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20
Q

What are the two leading causes of ischemia-related death for affected sickle cell patients?

A
  1. acute chest syndrome

2. stroke

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21
Q

T/F. About 8% of blacks in USA have sickle cell trait (homozygotes), and are essentially asymptomatic because less than half of the hemoglobin is abnormal and the concentration of HbS within the RBC is insufficient to cause sickling.

A

About 8% of blacks in USA have sickle cell trait (HETEROzygotes), and are essentially asymptomatic because less than half of the hemoglobin is abnormal and the concentration of HbS within the RBC is insufficient to cause sickling.

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22
Q

___ is an autosomal codominant ___ defect in the synthesis of alpha and beta globin chains due to ___ mutation or gene ___.

A

Thalassemia; quantitative; point; deletion

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23
Q

What is occuring in Thalassemia?

A

Decreased globin production results in decreased hemoglobin production, and anemia is the principal clinical manifestation. In addition, precipitation of the relative excess of the other globin chain within RBC causes membrane damage and premature destruction of RBC precursors in the marrow and spleen (ineffective erythropoiesis and extravascular hemolysis).

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24
Q

In almost all cases of Thalassemia there is a moderate to marked ___, ___ anemia with ___ cells and ___ stippling of the red cells present on the blood smear.

A

microcytosis (low MCV); hypochromic; target; basophilic

25
Q

Glucose-6-Phosphate Dehydrogenase (G6PD) deficiency is a ___ inherited (__-___) defect encountered primarily in blacks in which red cells are susceptible to ___ injury by drugs or toxins (antimalarials, sulfonamides, etc.).

A

metabolic; (X-linked); oxidant

26
Q

How are bite cell made?

A

The oxidized hemoglobin denatures, precipitates and attaches to the red cell membrane, which is less flexible and subjected to extravascular hemolysis by the spleen (takes a bite out of the cell)

27
Q

T/F. In the absence of a trigger, G6PD deficiency individuals are asymptomatic.

A

True.

28
Q

What disease occurs in utero due to blood group incompatibility between the mother and fetus?

A

Hemolytic disease of the newborn

29
Q

Explain how hemolytic disease of the newborn occurs?

A

This disease occurs in utero only when the fetal RBC express antigens inherited from the father that are not present in the mother. Fetal RBC that reach the maternal circulation during the third trimester of pregnancy or during childbirth can be recognized as foreign and stimulate an antibody response in the mother. When a sensitized mother is re-exposed to the foreign antigen during a subsequent pregnancy, the mother’s immune system makes antibodies (IgG) that cross the placenta and attach to the fetal RBC, resulting in extravascular hemolysis (antibody coated RBC are removed from circulation in liver and spleen) in the fetus.

30
Q

How is hemolytic disease of the newborn prevented?

A

Rh-negative mothers are given anti-D (Rhogam) within 72 hours of delivery of an Rh-positive fetus. The anti-D binds to the Rh-positive fetal cells and removes them from the maternal circulation before the mother can generate an antibody response and become sensitized.

31
Q

T/F. O infants of A or B group mothers are also at risk.

A

False, A and B infants of group O mothers are also at risk.
Certain group O mothers produce IgG anti-A or anti-B in addition to the usual IgM antibodies (which do not cross the placenta). Fortunately lysis of the fetal RBC is minimal, in part because fetal cells express A and B antigens weakly, and because other tissues also express A and B antigens and soak up the antibody.

32
Q

How is hemolytic transfusion reaction caused?

A

Following transfusion of ABO incompatible RBCs into a sensitized patient. Ab bind to transfused cells with complement activation, intravascular lysis of RBCs.

33
Q

What type of hemolysis occurs if a hemolytic transfusion reaction is delayed?

A

extravascular

34
Q

In which disorder does the patient make antibodies to his/her own RBCs?

A

autoimmune hemolysis

35
Q

What happens to antibody coated cells in autoimmune hemolysis?

A

Antibody-coated cells can be lysed (complement activation) or removed by the reticuloendothelial system (extravascular hemolysis).

36
Q

What is the hallmark cell of autoimmune hemolytic anemia? How is it produced? What test is given for patients with this disease?

A

spherocytes

Phagocytosis of antibody-coated RBC can lead to partial loss of red cell membrane (spherocytes)

Positive Coomb’s test (agglutination test)

37
Q

Match the following with its description:

  1. Cardiac valve prosthesis
  2. DIC

a. RBCs are lysed as they pass through fibrin clots/strands in the microcirculation
b. . Red cells are disrupted by physical trauma as they pass through areas of turbulence and abnormal pressure related to abnormal valve function

A

1 - b

2 - a

38
Q

___ are RBC fragments created by loss of a large protion of membrane due to mechanical trauma.

A

Schistocytes

39
Q

___ is an intravascular hemolysis involving parasites that infect RBC and cause lysis of RBC during maturation.

A

Malaria

40
Q

What is the most common cause of anemia worldwide?

A

iron deficiency anemia

41
Q

Match the following causes with the patients.

  1. inadequate intake
  2. increased demands
  3. increased loss

a. pregnancy, adolescents
b. infants
c. bleeding

A

1 - b
2 - a
3 - c

42
Q

T/F. In iron deficiency anemia, red blood cells become smaller (microcytic) and contain less hemoglobin (hypochromic) than usual.

A

True

43
Q

How is iron deficiency anemia diagnosed?

A

laboratory tests (decreased serum iron, decreased serum ferritin, and increased serum iron-binding capacity) and absent reticulocyte response

44
Q

What term is used to describe vitamin B12 and folate deficiency?

A

megaloblastic anemia

45
Q

Both B12 and folate are involved either directly or as cofactors in the synthesis of ___, one of the purine bases in DNA. The impaired DNA synthesis causes a delay in ___ division: nuclear size increases, but ___ synthesis and ___ maturation proceed normally.

A

thymidine; mitotic; RNA; cytoplasmic

46
Q

Megaloblastic anemia results in an abnormally large red cell precursor (___), ___ (increased/decreased) production of mature RBCs, and abnormally large red cells (macrocytes – high ___). ___ neutrophils may be seen secondary to the delay in mitotic division.

A

megaloblast; decreased; MCV; Hypersegmented

47
Q

T/F. B12 is found in fresh vegetables and has small body stores.

A

False, FOLATE is present in fresh vegetables and has small body stores.

B12 is found in animal foods with large body stores.

48
Q

T/F. Folate deficiency causes hematologic abnormalities in addition to neurologic symptoms.

A

False, B12 deficiency causes hematologic abnormalities in addition to neurologic symptoms.

49
Q

How is B12 metabolized?

A

Absorption of Vitamin B12 requires intrinsic factor (IF), a protein produced by parietal cells of the gastric mucosa. The IF-B12 complex passes to the distal ileum where it attaches to receptors on epithelial cells and is absorbed. The absorbed B12 is bound to transcobalamins (transport protein) in plasma which deliver it to the liver and other cells via the bloodstream.

50
Q

Pernicious anemia is caused by autoantibodies to ___ cells and ___ factor. B12 deficiency is associated with atrophic ____ (loss of gastric parietal cells, ___ and deficient IF).

A

parietal; intrinsic; gastritis; achlorhydria

51
Q

___ anemia is a ___ with markedly decreased bone marrow cellularity.

A

Aplastic; pancytopenia

52
Q

T/F. Over half of the cases of Aplastic anemia have no known predisposing cause (idiopathic), but viruses (hepatitis), drugs (chloramphenicol) and toxins (benzene, radiation) have been implicated.

A

True.

53
Q

What are the two pathogenic theories of aplastic anemia?

A
  1. an acquired defect in stem cell production

2. suppression of stem cells by T lymphocytes.

54
Q

___ ___ transplantation has been successful, especially in aplastic anemic patients less than ___ years old.

A

Bone marrow; 40

55
Q

In what condition is the bone marrow replaced by a tumor (metasasis or myeloma) or fibrosis? What characteristic misshapen RBCs can be found on blood smear?

A

Myelophthisic Anemia

“teardrops”

Platelets are also decreased

56
Q

___ polycythemia occurs with hemoconcentration from dehydration, vomiting, diarrhea, or excessive use of diuretics.

A

Relative

57
Q

___ absolute polycythemia occurs when a non-regulated (___) proliferation of red cells and myeloid cells is called polycythemia ___.

A

Primary; neoplastic; vera

58
Q

Cases of ___ absolute polycythemia have increased levels of ___, where as in ___ absolute polycythemia these levels are normal or suppressed.

A

secondary; erythropoietin; primary

Pathology (8 decks)

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