Extravascular Hemolytic Anemias Flashcards
Hereditary spherocytosis
most common defects
ankyrin, band 3, protein 4.2, spectrin
What is MCHC and when is it elevated
MCHC = mean corpuscular hemoglobin concentration
elevated in hereditary spherocytosis
because loss of cytoplasm as it’s eaten away by spleen concentrates Hb
What crisis can be seen in hereditary spherocytosis patients and what causes it
aplastic crisis
parvo B19
Old school test to diagnose hereditary spherocytosis
osmotic fragility test
because normal biconcave discs have room to expand in hypotonic solution
spherocytes are already maximally expanded so when they are in hypotonic solution they EXPLODE
Presentation of infant with sickle cell anemia
dactylitis
painful swelling of hands and feet
most commonly at 6 mo old when HbF goes away
Precipitating factors in sickle cell disease
low O2
altitude
acidosis
dehydration
Renal complication of sickle cell
renal papillary necrosis
also caused by DM
Acute chest syndrome
occlusion in pulmonary microcirculation in sickle cell disease often precipitated by pneumonia b/c pneumonia causes vasodilation in parts of lungs that's where they clot
How does sickle cell lead to increased risk of S. pneumoniae infection
autosplenetomy
during vaso-occlusive crisis
Increased incidence of what bone disease in sickle cell
Salmonella osteomyelitis
Tx of sickle cell
hydroxyurea
Substitution in sickle cell
Glu –> Val
Substitution in HbC disease
Glu –> lysine in β-globin
Classic finding in HbC disease
HbC crystals on peripheral smear within RBCs
look kind of like barrels
What is the pathology behind target cells
result from when cytoplasm decreases
dehydration 2˚ to membrane damage
==> relative excess of membrane, membrane folds in the middle and fills w/ Hb
appears red on smear
