Pathoma: Anemias Due to Intravascular Hemolysis and Underproduction

Question 1

Cells in the bloodstream have two surface molecules that accelerate the deactivation of complement: ___________.

Answer 1

decay accelerating factor (DAF) and membrane inhibitor of reactive lysis (MIRL)

Question 2

DAF and MIRL are anchored to RBCs with _______.

Answer 2

glycophosphatidylinositol (GPI)

Question 3

Paroxysmal nocturnal hemoglobinuria is a(n) _______ disorder that results from ________.

Answer 3

acquired; mutations in the myeloid stem cell lineage resulting in absence of the linker protein GPI

Question 4

________ tests for PNH because it induces __________.

Answer 4

Sucrose; complement activation

Question 5

DAF is also called ________.

Answer 5

CD55

Question 6

The main cause of death in paroxysmal nocturnal hemoglobinuria is __________.

Answer 6

thrombosis, because platelets also lack GPI and thus will be lysed; destruction of platelets leads to release of platelet granules, which activates clotting

Question 7

PNH increases the risk of _______.

Answer 7

AML

Question 8

Explain the pathophysiology of glucose-6-phosphate dehydrogenase deficiency (G6PD deficiency).

Answer 8

RBCs are constantly surrounded by oxidative molecules (because of the inflammatory processes that happen in the blood). As such, they need to be able to reduce those compounds. They degrade H2O2 with glutathione. Glutathione gets regenerated by glucose-6-phosphate dehydrogenase. Thus, lacking G6PD leads to increased H2O2 in cells.

Question 9

G6PD is inherited __________.

Answer 9

in an X-linked recessive fashion

Question 10

The Mediterranean variant is __________.

Answer 10

more extreme, because the half-life of the Mediterranean variant is shorter

Question 11

G6PD offers a _________

Answer 11

mild protection against malaria

Question 12

Oxidative stresses that can induce crises in those with G6PD include _________.

Answer 12

infections, fava beans, and drugs (sulfas, dapsone, and primaquine)

Question 13

Histologically, G6PD is characterized by ________.

Answer 13

Heinz bodies (precipitated hemoglobin) and bite cells

Question 14

Clinical presentations of G6PD include ________.

Answer 14

back pain (because hemoglobin is nephrotoxic) and hemoglobinuria

Question 15

G6PD is ___________ hemolysis.

Answer 15

intravascular

Question 16

Other than hereditary spherocytosis, _______ will also have spherocytes.

Answer 16

warm autoimmune hemolytic anemia

Question 17

IgG-mediated hemolytic anemia is associated with _________.

Answer 17

SLE, CLL, and certain drugs

Question 18

Warm IgG is treated by _________.

Answer 18

removing the offending drug (if it is drug-induced), giving steroids to dampen antibody production), giving IVIG (to give the splenic macrophages something else to eat), and splenectomy (as a last resort)

Question 19

___________ infection can lead to IgM autoimmune hemolytic anemia.

Answer 19

Mycoplasma pneumoniae and mononucleosis

Question 20

The direct Coombs test adds ________ to patients RBCs.

Answer 20

anti-IgG IgG

Question 21

Schistocytes (which are ________) result from _________.

Answer 21

helmet-cells; partially blocked small vessels that will shear RBCs as they pass by (such as with microthrombi)

Question 22

_________ can also lead to intravascular hemolytic anemia, because __________.

Answer 22

Malaria; RBCs lyse during the parasite’s life cycle

Question 23

The _________ virus leads to temporary aplastic anemia.

Answer 23

parvovirus B19