Thalassemia - SRS Flashcards
(77 cards)
Describe the RBC count you will find in thalassemias.
What about the Hgb?
RBC count will be normal
Hgb will be low
Interpret this CBC.
Hemoglobinopathy, Thalassemia
If you hear a patient is from S.E. asia, with a hemoglobinopathy what should you think?
Hemoglobin E
What is the structure of hemoglobin A composed of?
Tetramer of 4 globin chains and 4 heme molecules
The beta thalassemias are caused by mutations that diminish synthesis of Beta globin chains.
What are the types of mutations?
Describe the Beta chain levels in each.
B0 - Zero beta chains, absent b-globin synthesis
B+ - reduced, but detectable b-globin synthesis
What are the two mechanisms tha impaired B-globin synthesis results in anemia by?
underhemoglobinization - suboptimal O2 transport capacity
Diminished RBC survival d/t imbalance in alpha and beta globin synthesis
What are four major pathological problems that arise in beta thalassemia?
- Ineffective erythropoiesis
- extravascular hemolysis
- skeletal deformities
- systemic iron overload
In severe beta thalassemia what percent of red cell precursors make it out of the marrow?
Only 15 - 30% make it out. The rest die.
For the small fraction of RBC precursors that do escape the marrow, what problems do they have and what is the likely consequence?
They bear inclusions and membrane damage, thus they are prone to splenic sequestration and extravascular hemolysis
Beta thal major (B0 most often) is severe. What do these patients need to do regularly?
undergo transfusions
Describe the severity of B-Thal intermedia.
Are transfusions required?
Severe, but no regular transfusions
Characterize the severity of B thal minor.
Asymptomatic with mild or absent anemia.
Red cell abnormalities seen
When does B-thal major manifest?
6-9 months after birth, when Hbf switches to HbA
What are Hemoglobin levels in an untransfused b-thal major patient?
3-6 gm/dL
What is shown here?
X-ray of a skill of a b-thal patient showing new bone formation producing perpindicular radiations resembling a crew cut. Excessive compensatory hematopoiesis
What is going on with this kid?
Cheek bones are deformed d/t extraperiosteal growth to accomodate increased hematopoiesis.
PAtient also has secondary hemochromatosis d/t increased iron absorption post hemolysis
What does this patient have?
What would you possibly see on peripheral blood smear?
B-thal minor
smear = RBC abnormalities, microcytosis, basophilic stippling, and target cells
Recognition of B-thal trait is important for what two reasons?
- resembles hypochromic microcytic anemia of iron deficiency
- implications for genetic counseling.
How can you differentiate between anemia of iron deficiency and b-thal minor?
Does not improve with iron
If a patient is genotype -/-,alpha/alpha
What is their alpha thalassemia status?
Thalassemia trait - two deletions
If a patient has three alpha-globin deletions what do we call their condition?
Hemoglobin H disease
If someone has loss of four alpha-globin genes then they have what?
Hydrops fetalis/hemoglobin Barts - and they die
If a patient has one alpha globulin gene lost then they are?
A silent carrier
What is described here?
Diminished production of alpha globin and patient is normal
Silent carrier
