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28 Cards in this Set

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  • Back
MCC of hereditary hemolytic anemias in Northern Europeans.
Hereditary Spherocytosis (HS)
Inheritence of HS
What is meant by compensated hemolysis?
BM can increase erythroid production as much as 10X baseline. Patients w/ lifelong anemias can have normal Hb b/c of this compensation (BM is turned up). The anemia won't be recognized unless severe stress goes beyond the BM's ability to compensate.
Pathophysiology of HS
Most deficient in akyrin (locks spectrin into membrane)

25% lack Band 3
What is meant by a "private mutation"?
mutation found in only one family line (e.g. the Thrashes)
What is intrasplenic conditioning?
cells are unable to deform and migrate through spleen.... they spend more time and accrue more damage w/ each pass, eventually leading to destruction
What is the usual presentation of HS?
usually asymptomatic

bilirubin slightly high, Hb slightly low, little jaundice, pigmented bilirubing gallstones
What is the result of the Coombs test in HS?
NEGATIVE b/c there is no immune deposition on RBCs
Diagnosis of HS
peripheral smear
negative Coombs
Smaller RBCs w/ more volume to surface
MCV is normal or decreased
Hb elevated
GOLD STANDARD - osmotic fragility test
What is the osmotic fragility test?
As salt is diluted, cell w/ swell and explode

Normal person's cells explode at .4%, HS patient will explode at a less dilute conc.

More dramatic if cells are incubated overnight and lose ATP
What is erythroid aplastic crisis?
occurs in patient's w/ compensated lifelong anemia

infection w/ B19 parvovirus which infects erythroid precursors

also caused by B12 or folate deficiency, other viruses, drugs
What is person w/o a spleen at risk for?
infection w/ encapsulated organisms (Pneummococcus, H flu)
What are normal post splenectomy lab values?
elevated WBC
elevated platelets
abnormal RBCs
Howell Jolly bodies - diagnostic for splenectomy, tiny clump of RNA normally removed by spleen
Inheritence of Hereditary Eliptocytosis (HE)?
Pathophysiology of HE?
spectrin deficiency, cells pulled apart, leads to membrane fragmentation and hemolysis

Osmotic fragility is LESS USEFUL
Describe Common HE.
no clinically significant
most have minimal hemolysis
if pregnant or having surgery, consult surgery
Describe Hereditary Pyropoikilocytosis.
"pyro" b/c smear resembles that of burn patients

More rare and severe form of HE

Usually manifests in infancy
Describe Southeast Asian Ovalocytosis
Common in SE Asia
Oval RBC w/ longitudinal slit
Marked malaria resistance
Mutation in Band 3
Mild hemolysis, very rigid cells
Describe Stomatocytes
Caused by?
Slit shape of ovalocytes
Abnormality in membrane potassium pumps

Describe Spur cell anemia (Acanthocytosis)?
Caused by ?
Found in ?
spur or star looking cells

Problem w/ cholesterol metabolism -> too much cholesterol -> very rigid membranes -> lysing
Inherited abnormality of RBC shape,due to molecular abnormalities of (4):
1) cytoskeleton
2) lipid bylayer
3) membrane proteins
4) cation permeability
What is the purpose of having RBCs in the shape of a biconcave disc (2)?
1) Allows for excess surface area for gas exchange
2) Allows for deformation as it squeezes through spleen and microvessels
What is meant by the asynchronous distribution of lipids in a RBC membrane?
Negatively charged lipids face the inside and neutral ones face the outside. This is b/c the negative ones are thrombogenic.

Flipases uses ATP to maintain this synchrony.
A mutation in spectrin is usually seen in ?
hereditary elliptocytosis (HE)

Spectrin is in the largest quantity of the cytoskeletal proteins. It forms a heterotetramer w/ 2 spectrins wrapped around each other.
What anchors spectrin to Band 3 in the membrane?

Holds Ankyrin to Band 3?

Anionic exchange protein that locks part of structure?

Protein 4.2

Band 3
Deficiencies in which three proteins cause spherocytic anemia?
ankyrin, protein 4.2, and band 3
Which protein helps stabilize the structure but does not directly interact?

Helps Actin anchor to lipid bilayer via glycophorin C?

Filaments that are highly regulated and rapidly changing?
Glycophorin A

Protein 4.1

Most important property of RBCs that enables them to survive is their?