Hema. Mod.A Lec5 Flashcards
(25 cards)
splenomegaly can be due to (2)
extramedullary hematopoiesis
and extravascular hemolysis
splenomegaly is not found in which type of anemia ?
iron deficiency anemia
characteristics of thalassemia
1- high reticulocyte due to ineffective erythropoiesis
2-normoblast in peripheral blood
3-target cells
4-microcytes
difference between thalassemia and sickle cell anemia according to erythropoiesis
thalassemia leads to ineffective erythropoiesis while sickle cell anemia doesn’t lead to ineffective erythropoiesis
inheritance in sickle cell anemia and thalassemia
both mother and father must be carriers
Hb abnormalities result from (3)
1-synthesis of abnormal Hb (leads to sickle cell anemia)
2-reduced rate of synthesis of a and b globin chains (lead to a and b thalassemia)
3-if the mother is a carrier of sickle and father is carrier of thalassemia then it leads to sickle thalassemia
clinical classification of thalassemia (3)
major:
depends on blood transfusion
intermedia:
doesn’t depend on blood transfusion but has all features of thal.major (blood transfusion every once in a while)
trait/minor:
asymptomatic, carries the affected genes, no blood transfusion
genetic classification of thalassemia: (2)
alpha thalassemia
beta thalassemia
alpha thalassemia
the affected genes are alpha genes
-there are 4 alpha genes, 2 from mom and 2 from dad
alpha note means all alpha genes are lost
alpha+ means 3 genes are lost
cause of alpha thalassemia: deletion of genes
types of alpha thalassemia
1-alpha thal.major:
HYDROPS FETALIS: intrauterine fetal death
due to deletion of all 4 genes of alpha chain
2-alpha thal.intermedia:
HbH disease: due to deletion of 3 alpha genes
3-alpha thal.trait/minor:
carrier, asymptomatic
may have 2 genes normal and 2 abnormal
or (3 genes abnormal and 1 normal ?????????)
beta thalassemia
affected genes are B-genes
genes of B-chain are 2 genes, 1 from mom and 1 from dad
types of beta thalassemia:
1- B note thalassemia (major):
all genes are lost
2-B+ thalassemia (minor):
small amount of gene is present
cause: due to POINT MUTATION of genes which lead to change in a.a of globin
pathogenesis of B-Thal.Major:
In B-Thal there are no B genes (or reduced) so alpha chain increases and precipitates in precursors of early RBC’s which cause them to DESTRUCT IN BM (ineffective erthropoiesis)
destruction of RBC’s lead to increase in LDH and Bilirubin
BM becomes unable to synthesize more RBC’s so synthesis occurs in liver and spleen (EXTRAMEDULLARY HEMATOPOIESIS) which lead to HEPATOSPLENOMEGALY
Hypoxia occurs, stimulates the kidney to secrete EPO which stimulates production of abnormal cells
Also lead to thinning of bone (becomes friable)
On examination by X-Ray bone appears as (in b thal.major)
Hair on end appearance
in b thal.major, prominence of bone is due to
over expansion of BM
in b thal.major iron overload is due to
increased blood transfusion , because they have more iron absorption from intestine due to low hepcidin
pathogenesis of alpha thalassemia:
same as b thalassemia
complication of b thal.major
1-iron overload increase deposition of iron lead to damage
2-infections: after splenectomy , infections increase because spleen has macrophage and with no spleen macrophages are low and this leads to many infections like: Meningococcal, HBV, HCV, Hemophilus, HIV, pneumococcus, yersinia(diarrhea).
so he should be vaccinated after splenectomy
diagnosis of alpha thalassemia:
in case of Hb-H disease:
1-CBC shows microcytic hypochromic
2-Reticulocyte preparation:
Reticulocyte has RNA and blue spots called Hb-Bart’s granules appear
Hb-Barts granules are precipitated B chains
3-Hb electrophoresis:
Hb-H band appear
Diagnosis of B-Thala.major
by electrophoresis:
HbA absent or 10%
HbF present
HbA2 little amount
Diagnosis of B-thala.minor (carrier/trait)
HbA present
HbF not present or small amount
HbA2 high (>3.5)
mild hypochromic microcytic
red cell count (>5.5)
Diagnosis of Alpha-Thala.Trait (minor)
by DNA analysis
Types of sickle beta thalassemia
sickle cell b0 thala
sickle cell b+ thala
sickle beta thalassemia
both mother and father must be carriers
MCV and MCH lower than sickle cell disease
CLINICAL PICTURE
same as sickle cell disease + splenomegaly
HB electrophoresis:
in Sickle B0
HbF present
HbS present
HbA absent
In Sickle B+
HbF present
HbS present
HbA few
CBC shows microcytic hypochromic
