Flashcards in Disorders of Hemoglobin Deck (31)
2 main categories of hemoglobin disorders?
Consequences of structural abnormalities?
altered O2 affinity
increased susceptibility to oxidation to methemoglobin
How to diagnose globin problem in lab?
HPLC (high performance liquid chromatography)
What to patients with sickle cell trait gain?
protection against malaria
What is the extent of HbS polymerization dependent on?
time & concentration
List some clinical settings that predispose to sickling
What is the lifespan of a sickled cell?
Major effects of RBC sickling
chronic hemolysis and microvascular occlusion with resultant tissue hypoxia and infarction
When do the effects of sickle cell first show up after birth?
10-12 weeks of age
Main clinical manifestations (14)
acute pain crisis
acute chest syndrome
splenic sequestration crisis
What is most common cause of death in sickle cell?
acute chest syndrome
What is the main cause for aplastic crisis in sickle cell?
parvovirus B19 infection
What happens during a splenic sequestration crisis?
acute pooling of blood in spleen
drop in Hb
potential for hypovolemic shock
Why does megaloblastic anemia cocur in Sickle Cell?
increased folate consumption because of chronic erythroid hyperproliferation
Lab findings in sickle cell
sickeld cells, target cells, polychromasia
post splenectomy changes in adults
What can happen to the kidneys in pts w/sickle cell trait?
sub clinical damage
What is Hemoglobin SC disease?
HbC form glu to lys substitution
milder than SS usually
What is HbS/Beta thalasemia?
hetero HbS with trans beta thalassemia allele
asymptomatic to SS like
What is a thalassemia?
inherited disorder characterized by decreased production of structurally normal globin chains
Distribution of beta thal?
mediterranean, middle east, some parts of india and pakistan, SE asia
distribution of alpha thal?
africa, mediterranean, middle east, SE asia
Features of thalassemai?
microcytic, hypochromic anemias of varying severity
Beta-Thal major features
absense in beta chain production on both beta alleles
bizarre red cell morphology
hybrid of hemolytic anemia and ineffective erythropoiesis
Problems in inadequately transfused beta thal major?
mongoloid facies/bony abnormalities/frontal bossing
death in childhood
Beta thal minor features
common in mediterranean and asian populations
mild or no anemia
scattered target cells and basophilic stippling
Beta thal intermedia
Alpha thalassemia features/types
silent carrier (1 del)
trait (2 del)mild
HbH disease (3 del) mild-mod chronic hemolytic anemia HbH is beta tetramers
Hydrops fetalis (4del) stillborn or die first few hours of life
Effects of HU (hydroxiuria) dose escalation in sickle cell
Does cis or trans mutation in alpha thal matter for treatment?
no but it does for genetic counseling