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28 Cards in this Set
- Front
- Back
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MCC of hereditary hemolytic anemias in Northern Europeans.
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Hereditary Spherocytosis (HS)
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Inheritence of HS
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AD
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What is meant by compensated hemolysis?
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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.
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Pathophysiology of HS
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Most deficient in akyrin (locks spectrin into membrane)
25% lack Band 3 |
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What is meant by a "private mutation"?
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mutation found in only one family line (e.g. the Thrashes)
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What is intrasplenic conditioning?
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cells are unable to deform and migrate through spleen.... they spend more time and accrue more damage w/ each pass, eventually leading to destruction
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What is the usual presentation of HS?
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usually asymptomatic
bilirubin slightly high, Hb slightly low, little jaundice, pigmented bilirubing gallstones |
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What is the result of the Coombs test in HS?
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NEGATIVE b/c there is no immune deposition on RBCs
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Diagnosis of HS
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FH
peripheral smear negative Coombs Smaller RBCs w/ more volume to surface MCV is normal or decreased Hb elevated GOLD STANDARD - osmotic fragility test |
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What is the osmotic fragility test?
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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 |
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What is erythroid aplastic crisis?
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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 |
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What is person w/o a spleen at risk for?
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infection w/ encapsulated organisms (Pneummococcus, H flu)
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What are normal post splenectomy lab values?
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elevated WBC
elevated platelets abnormal RBCs Howell Jolly bodies - diagnostic for splenectomy, tiny clump of RNA normally removed by spleen |
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Inheritence of Hereditary Eliptocytosis (HE)?
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AD
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Pathophysiology of HE?
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spectrin deficiency, cells pulled apart, leads to membrane fragmentation and hemolysis
Osmotic fragility is LESS USEFUL |
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Describe Common HE.
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no clinically significant
most have minimal hemolysis if pregnant or having surgery, consult surgery |
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Describe Hereditary Pyropoikilocytosis.
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"pyro" b/c smear resembles that of burn patients
More rare and severe form of HE Usually manifests in infancy |
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Describe Southeast Asian Ovalocytosis
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Common in SE Asia
Oval RBC w/ longitudinal slit Marked malaria resistance Mutation in Band 3 Mild hemolysis, very rigid cells |
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Describe Stomatocytes
Caused by? |
Slit shape of ovalocytes
Abnormality in membrane potassium pumps NOT A MEMBRANOPATHY!!! |
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Describe Spur cell anemia (Acanthocytosis)?
Caused by ? Found in ? |
spur or star looking cells
END STAGE LIVER DISEASE - will die soon Problem w/ cholesterol metabolism -> too much cholesterol -> very rigid membranes -> lysing |
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Inherited abnormality of RBC shape,due to molecular abnormalities of (4):
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1) cytoskeleton
2) lipid bylayer 3) membrane proteins 4) cation permeability |
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What is the purpose of having RBCs in the shape of a biconcave disc (2)?
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1) Allows for excess surface area for gas exchange
2) Allows for deformation as it squeezes through spleen and microvessels |
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What is meant by the asynchronous distribution of lipids in a RBC membrane?
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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. |
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A mutation in spectrin is usually seen in ?
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hereditary elliptocytosis (HE)
Spectrin is in the largest quantity of the cytoskeletal proteins. It forms a heterotetramer w/ 2 spectrins wrapped around each other. |
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What anchors spectrin to Band 3 in the membrane?
Holds Ankyrin to Band 3? Anionic exchange protein that locks part of structure? |
Ankyrin
Protein 4.2 Band 3 |
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Deficiencies in which three proteins cause spherocytic anemia?
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ankyrin, protein 4.2, and band 3
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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 Actin |
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Most important property of RBCs that enables them to survive is their?
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deformability
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