265b congenital anemia Flashcards Preview

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Flashcards in 265b congenital anemia Deck (23):
1

RBC membrane proteins that are important - integral and peripheral?

integral - band 3

peripheral - spectrin and ankyrin

2

ankyrin fxn

link spectrin t0 band 3

3

spectrin

a and b subunits that self associate - supports lipid bilayer as a scaffold

4

band 3

Cl and HCO3 exchange in bilayer

5

hereditary spherocytosis (HS) - cause?

Defect in proteins interacting with RBC membrane skeleton and plasma membrane (e.g., ankyrin, band 3, protein 4.2, spectrin).

6

hereditary spherocytosis (HS) - findings?

hemolysis --> anemia, jaundice
Splenomegaly
aplastic crisis (parvovirus B19 infection).

7

hereditary spherocytosis (HS) - labs?

osmotic fragility test+.

Eosin-5-maleimide binding test useful for screening.

^MCHC, reticulocytosis, ^RCDW

Normal to decreased MCV with abundance of cells; masks microcytia.

8

hereditary spherocytosis (HS) - Rx?

splenectomy, transfusions

9

hereditary spherocytosis (HS) - RBC appearance?

Less membrane causes small and round RBCs with no central pallor (^ MCHC, ^ red cell distribution width) --> premature removal of RBCs by spleen. (AKA spherocytes)

10

hereditary spherocytosis (HS) - findings?

hemolysis --> anemia, jaundice
Splenomegaly
aplastic crisis (parvovirus B19 infection).

11

RBC metabolism

no nuclei/mito

uses 2 pathways

1) pentose phosphate pathway to make NADPH using G6PD

2) Glycolysis to make ATP - pyruvate kinase is major rate limiting step

12

hereditary spherocytosis (HS) - Rx?

splenectomy

13

glycolysis in RBCs

Glucose --> G6P via hexokinase then F6P

F6P --> F1,6P via PFK I then to PEP

PEP --> pyruvate via PK (generates ATP)

pyruvate --> lactate



14

Hereditary elliptocytosis - rbc appearance? cause?

elliptocyte due to spectrin deficiency

15

RBC metabolism

no nuclei/mito

uses 2
1) pentose phosphate pathway to make NADPH using G6PD

2) Glycolysis to make ATP - pyruvate kinase is major rate limiting step

16

G6PD deficiency - findings? RBC smear appearance?

abdominal/back pain, hemoglobinuria a few days after oxidant stress --> coca-cola urine + jaundice, fever

Labs: blood smear shows RBCs with Heinz bodies (Hg is denatured and precipitates in RBCs) and bite cells.

“Stress makes me eat bites of fava beans with Heinz ketchup.”

17

glycolysis in RBCs

Glucose --> G6P via hexokinase then F6P

F6P --> F1,6P via PFK I then to PEP

PEP --> pyruvate via PK (generates ATP)

pyruvate --> lactate



18

G6PD deficiency - inheritance?

X-linked recessive

19

G6PD deficiency - pathogenesis?

Defect in G6PD --> reduced glutathione --> ^ RBC susceptibility to oxidant stress.

Hemolytic anemia following oxidant stress (classic causes: sulfa drugs, antimalarials, infections, fava beans).

20

G6PD deficiency - findings?

Back pain, hemoglobinuria a few days after oxidant stress.

Labs: blood smear shows RBCs with Heinz bodies and bite cells.

“Stress makes me eat bites of fava beans with Heinz ketchup.”

21

pyruvate kinase deficiency - genetics?

AR

22

pyruvate kinase deficiency - pathogenesis?

Defect in pyruvate kinase--> decreased ATP --> rigid RBCs.

23

pyruvate kinase deficiency - findings?

hemolytic anemia in a newborn --> hyperbilirubinemia

anemia, jaundice (but no increase in hemolysis?)

increased 2,3 DPG --> right shift of O2 curve