RBCs: 5.5: Normocytic w/ Extravascular Hemolysis Flashcards
What is hereditary spherocytosis?
an inherited defect of RBC cytoskeleton membrane tethering proteins (ankyrin, spectrin, or band 3.1)
A large range in RBC size will be indicated in what test?
increased RDW
What is the problem with spherocytes?
they’re less able to maneuver thru the spleen- they are then consumed by splenic macs –> anemia
Why does MCHC increase in hereditary spherocytosis?
bc the cell shrinks, which increases hemoglobin concentration
What are the physical s/s of hereditary spherocytosis?
splenomegaly (hypertrophy), jaundice, increased unconjugated bilirubin, and bilirubin gallstones
Increased unconjugated bilirubin –> ?
jaundice
Pts with hereditary spherocytosis have an increased risk of _____ with parvovirus B19 infection of erythroid precursors.
aplastic crisis
What medication increases HbF?
hydroxyurea
What causes sickle cell anemia?
an auto recessive mutation in the beta-chain of Hb (glu is replaced with val)
How is hereditary spherocytosis diagnosed?
on osmotic fragility test, the spherocytes will swell and burst in hypotonic solution
What is the tx for hereditary spherocytosis?
splenectomy (anemia resolves but spherocytes persist- that’s ok- and Howell-Jolly bodies will emerge)
What are Howell-Jolly bodies?
fragments of DNA left inside RBCs (look like a blue dot)
Pts with hereditary spherocytosis have an increased risk of aplastic crisis with parvovirus B19 infection of ______ .
erythroid precursors
What is the mutation in sickle cell anemia?
glu –> val
What is the Hg pattern in sickle cell disease?
alpha-2- beta2S (2 abnormal beta genes –> 90% HbS)
What is the problem with HbS?
it polymerizes when deoxygenated (hypoxemia, dehydration, acidosis) –> aggregate –> sickle shape
Pts with hereditary spherocytosis have an increased risk of aplastic crisis with _____ infection of erythroid precursors.
parvovirus B19
If RBCs lyse, what is spilled into the blood? What molecule binds to this?
free hemoglobin; haptoglobin
Why are there target cells on sickle cell blood smears?
membrane damage to RBCs causes dehydration –> cell shrinks its cytoplasm, but Hb doesn’t decrease
What is dactylitis?
swelling of the hands and feet d/t vasoocclusive infarcts of bones, esp in infants (1st presentation of sickle cell pts)
What kind of bacteria are Sickle Cell pts susceptible to?
encapsulated (H. flu, Strep pneumo)
Where do antibodies primarily come from?
the spleen
Name the encapsulated bacteria.
"Please SHINE my SKiS" Pseudomonas aerug. Strep pneumo H. influ type B Neisseria meningiditis E. coli Salmonella Klebsiella group B strep
What is vasoocclusive crisis in the kidney called?
renal papillary necrosis
What is the hemoglobin pattern in sickle cell trait?
lots of alpha-2-beta-2 (HbA) and a little alpha-2-beta-2S (HbS)
What are the s/s of sickle cell trait?
usually asymptomatic
What drug causes any cell with HbS to sickle?
metabisulfite
What test confirms the presence of HbS?
electrophoresis
What is HbA composed of?
alpha-2-beta-2
What causes hemoglobin C?
a mutation in the beta-chain (glu to lysine) *** hemoglobin C has ly-C-ine
What is characteristic of HbC in a blood smear?
HbC crystals
What is the inheritance of hemoglobin C?
auto recessive
