Microcytic anemias Flashcards
Causes of iron deficient anemia
iron loss
decreased iron intake
decreased iron absorption
increased iron demand
what is hepcidin
prevents iron absorption
what is transferrin
iron-binding glycoprotein that transports ferric iron to erythroid precursor cells in bone marrow for hemoglobin synthesis
contributes to hepatocyte iron
what is ceruloplasmin
oxidizes ferrous iron to ferric iron
what is ferroportin
transport protein atop epithelial cells to allow iron in from the blood
what is TBIC
measure of transferrin in blood inverse of ferritin level
what is ferritin
iron storage molecule
where is ferritin highest in liver
parenchymal cells
where else is ferritin found
bone
skeletal muscle
spleen
where is ferritin derived from in extrahepatic sites
degraded RBC’s in macrophages
what is hemosiderin
iron storage molecule
what is normal percent iron saturation
~33%
what will you expect to see in iron deficiency anemia
microcytic, hypochromic anemia
low hepcidin
low ferritin
low % saturation
low Hb and Hct
increased RDW
increased TBIC
increased free erythrocyte protoporphyrin (FEP)
components of hemoglobin
heme
iron
protoporphyrin globin chains
manifestation of iron deficiency anemia
Plummer Vinson Syndrome
esophageal web
atrophic glossitis
Dysphagia
beefy red tongue
causes of sideroblastic anemia
x linked ALA-synthase defect
B6 deficiency
lead poisoning
drugs (chloramphenicol, isoniazid, linezolid)
copper deficiency
myelodysplastic syndrome
malignancies
histologic manifestations of sideroblastic anemia
ringed sideroblasts
basophilic stippling
what causes basophilic stippling
impaired RBC division
sideroblastic anemia manifestations
porphyrias
sideroblastic anemia labs
microcytic anemia
increased ferritin
increased iron
increased transferrin saturation
basophilic stippling
ringed sideroblasts
why is anemia of chronic disease a microcytic anemia
IL-6 promotes inflammation, which increases acute phase reactants (hepcidin)
increased hepcidin decreases iron absorption, which decreases available iron
decreased EPO synthesis leads to decreased RBC synthesis
what could cause impaired RBC production
chronic microbial infections
chronic immune disorders
neoplasms
anemia of chronic disease labs
Early:
normocytic anemia
Late:
microcytic anemia low iron low TBIC high ferritin low reticulocytes
what are thalassemias
disorders caused by inherited mutations that decrease the synthesis of globin chains, causing ineffective erythropoiesis
what chromosome is beta subunit located
chromosome 11
what chromosome is the alpha subunit located
chromosome 16
what is the problem in beta thalassemias
defective HbA synthesis leads to under Hb hypochromic RBCs with decreased capacity to carry oxygen
how does beta thalassemia minor usually present
asymptomatic
beta thalassemia minor labs
increased HbA
increased HbA2 and HbF
microcytic hypochromic RBCs
what happens in beta thalassemia major
- unpaired alpha chains precipitate and damage RBC membranes
- leading to ineffective erythropoiesis
- ultimately extravascular hemolysis in the spleen
- massive erythroid hyperplasia
- ultimately expanded hematopoiesis
how does beta thalassemia major present
crewcut appearance
chipmunk facies
splenomegaly
HbA2
HbF
little to no HbA
microcytic hypochromic RBCs
target cells
what is a risk of beta thalassemia major
aplastic crisis with ParvoB19
which alpha thalassemia is asymptomatic
1 gene deletion
what happens when 2 alpha genes are deleted on chromosome 16
mild anemia with increased RBCs
what is a transdeletion and who does it occur most in
deletions in 2 chromosomes
African (Americans)
What is a cis deletion and who does it occur most in
deletions on the same chromosome
Asians
which deletion of alpha thalassemia is most severe and why
cis deletion is more dangerous because it is on the same chromosome, posing increased risk of transmitted severity to their progeny
what happens when 3 alpha genes are deleted on chromosome 16
severe anemia
beta chains form tetramers
what are tetramer beta globin chains called
HbH
what happens when 4 alpha genes are deleted on chromosome 16
hydrops fetalis
gamma chains form tetramers
what are tetramer gamma globin chains called
Hb Barts
which forms of Hb damage RBCs
HbH
Hb Barts
composition if HbA
2 alpha and 2 beta chains
composition of HbA2
2 alpha and 2 Delta chains
composition of HbF
2 alpha and 2 gamma chains
composition of Hb Barts
4 gamma chains
composition of HbH
4 beta chains
Labs for Iron deficient Anemia
- Iron level
- Ferritin
- TIBC
- RDW
also microcytic hypochromic RBCs
normal- low reticulocyte count
increased serum transferrin
anisocytosis- appearance of RBCs of different sizes
Labs for Anemia of Chronic Disease
- Iron level
- Ferritin
- TIBC
- RDW
increased hepcidin
Labs for Sideroblastic Anemia
- Iron level
Ferritin
TIBC
RDW
Ringed Sideroblasts
Basophilic stippling
Labs for Thalassemias
Iron level
Ferritin
TIBC
RDW
Target cells
teardrop cells
reactive hyperplasia in bone marrow
crew cut appearance
chipmunk facies
