Bl Week 1 Objective 7

Front 1

What are three general categories of causes of anemia?

Back 1

1. Abnormal red cell production
2. Increased red cell destruction
3. Blood loss

Front 2

What are some causes of abnormal red cell production?

Back 2

Iron deficiency
Pernicious anemia (B12)
Folate deficiency
Lead poisoning
Thalassemia
Aplastic Anemia

Front 3

What are Megaloblastic anemias?

Back 3

A diverse group of anemias that have in common impaired DNA synthesis and distinctive morphological changes in the blood and bone marrow.

Front 4

What are the two principle types of Megaloblastic anemia?

Back 4

1. Pernicious anemia (the major form of B12 deficiency anemia)
2. Folate deficiency anemia

Front 5

Why are B12 and folic acid important for DNA synthesis?

Back 5

They are coenzymes required for the sythesis of thymidine one of the four bases of DNA

Front 6

When is pernicious anemia generally diagnosed?

Back 6

In the 5th to 8th decades.

Front 7

Which takes longer to develop a B12 deficiency or Folate deficiency?

Back 7

A B12 deficiency develops over years whereas a folate deficiency can develop over months.

Front 8

In whom are folate deficiencies common?

Back 8

Those with dietary inadequacies such as chronic alcoholics, the indigent and the very elderly.

Front 9

What is probably the most common nutritional disorder in the world?

Back 9

Iron deficiency.

Front 10

In whom is iron deficiency the most common?

Back 10

Developing countries or North America in toddlers, adoslescent girls and women of childbearing age.

Front 11

When is folate used at a greater rate?

Back 11

Pregnancy and lactation, malignancy, inflammation, hemolytic anemia

Front 12

What are three main causes of iron deficiency?

Back 12

Blood loss (men GI bleeding)
Iron poor diet
Malabsorption

Front 13

How is iron balance regulated?

Back 13

By regulating absorption of dietary iron.(there is no regulated pathway of excretion)

Front 14

What needs to happen before iron deficiency anemia manifests itself?

Back 14

1.Iron stores are completely depleted
2. Low serum iron, serum ferritin, and transferrin saturation

Front 15

How does lead poisoning in children cause abnormal red cell production?

Back 15

Lead interferes with the final step in heme synthesis, leading to a large increased in FEP(Free Erythrocyte Porphyrins)

Front 16

What is a sign of lead poisoning?

Back 16

Lead lines in gums.

Front 17

What is aplastic anemia?

Back 17

A syndrome of marrow failure associated with pancytopenia(anemia, neutropenia and thrombocytopenia)

Front 18

What are some causes of aplastic anemia?

Back 18

Exposure to chemical and drugs, whole body irradiation, following viral infections

Front 19

What are two possible mechanisms of aplastic anemia?

Back 19

1. Suppression of stem cell function by activated T cells.
2. Fundamental stem cell abnormality. Some marrow insult causes genetic damage that limits proliferative and differentiative capacity of the stem cells.

Front 20

In whom does aplastic anemia typically occur?

Back 20

Any age and either sex.

Front 21

What are five causes of anemia due to red blood cell destruction?

Back 21

1. Hereditary spherocytosis
2. Sickle Cell Anemia
3. Thalassemia
4. Autoimmune Hemolytic anemia
5. G6PD deficiency

Front 22

What causes hereditary spherocytosis?

Back 22

An inherited defect in spectrin, ankyrin, band 4.2 or band 3 thatleads to reduced membrane stability. This lack of vertical membrane stability predisposes the cells to loss of membrane fragments during exposure to shear stresses in the circulation and thus the formation of spheres (less surface area and same volume)which are vulnerable to splenic sequestration and destruction.

Front 23

When and how does Hereditary spherocytosis typically present?

Back 23

1. Minority of patients present at birth with jaundice requiring transfusion.
2. 20-30% asymptomatic (increased erythropoiesis compensates)
3. Majority -chronic hemolytic anemia of mild to moderate severity, punctuated by aplastic crises.

Front 24

What causes sickle cell anemia?

Back 24

A point mutation in the Beta-globin chain which produces sickle hemoglobin (HbS).

Front 25

Physiologically how is sickle hemoglobin (HbS) different than normal adult hemoglobin (HbA)?

Back 25

When deoxygenated, HbS molecules undergo aggregation and polymerization forming long needle-like fibers within the red cell thus producing a distorted sickle shape.

Front 26

What are three key features of sickle cell disease presentation?

Back 26

1. Severe anemia
2. Vaso-occlusive complications
3. Chronic hyperbilirubinemia

Front 27

Why are those with sickle cell disease more susceptible to infection?

Back 27

A. Vaso-occlusive complications impair splenic function:
children- congestion and poor flow
adults -infarction and autosplenectomy
B. Defects in the alternative complement pathway impair opsonization of encapsulated bacteria.

Front 28

What causes thalassemia?

Back 28

Genetic lesion causing deficient synthesis of either the Alpha or Beta globin chains of HbA.

Front 29

What two pathological processes are caused by lack of globin chains?

Back 29

1. Hypochromia -low intracellular hemoglobin
2. Intracellular excess of unpaired globin chains which aggregate into insoluble inclusions.

Front 30

Why are these intracellular inclusions significant?

Back 30

They lead to premature destruction of maturing erythroblasts in the marrow(ineffective erythropoiesis) and lysis of mature red cells in the spleen.

Front 31

What is Autoimmune Hemolytic Anemia (AIHA)?

Back 31

Occurs when there is an immune response against red cells and pieces of their membrane are broken off resulting in spherocytosis.

Front 32

What are the two types of AIHA?

Back 32

1. Warm antibody type
2. Cold Antibody type

Front 33

What is the pathogenesis of the warm type?

Back 33

IgG coated red cells bind Fc receptors on monocytes and splenic macrophages which causes loss of cell membrane through "partial phagocytosis" and eventually leads to extravascular destruction.

Front 34

What is the pathogenesis of the cold type?

Back 34

IgM antibodies bind avidly to RBCs at cold temps causing agglutination and the fixation of complement to their surface. This can lead to complement mediated hemolysis or removal of the opsonized red cells by splenic macrophages after rewarming.

Front 35

What is G6PD?

Back 35

Glucose-6-phosphate dehydrogenase an enzyme that is essential for the breakdown of compounds such as H2O2 which are responsible for oxidant injury.

Front 36

Who is more at risk for G6PD deficiency?

Back 36

Those from the "malaria belt" and males (X-linked)

Front 37

What can trigger hemolysis in those with G6PD?

Back 37

Things that increase oxidants:
-Oxidant drugs(antimalarials(primaquine, choloroquine),sulfonamides, nitrofurantoins...)
-infections (viral hep, pneumonia, typhoid fever)
-foods (fava beans)