Thalassemia Flashcards
what is thalassemia?
hypochromic, microcytic, and is a result of a defect in either the alpha or beta globin chains
what causes the defect in an alpha or beta chain in thalassemia?
when genes related to the globin protein are missing or changed
what is the hallmark of thalassemia?
an imbalance globin chain synthesis
this is the most common single-gene disorder in the world
thalassemia
is thalassemia inherited or spontaneous?
inherited
this type of thalassemia is associated with chromosome 11
Beta-thalassemia
this type of thalassemia is associated with chromosome 16
Alpha-thalassemia
what is the coloration and size associated with thalassemia?
hypochromic and microcytic
what are the most common causes of Beta-thalassemia?
deranged splicing of the mRNA precursor or premature termination of mRNA translation
what causes chipmunk facies and frontal bossing?
extramedullary erythropoiesis since RBCs can no longer be made in bone marrow or traditional locations
ineffective erythropoiesis can lead to excessive absorption of what?
iron
in thalassemia, is hepcidin suppressed or encouraged?
suppressed
what organ can be damaged in thalassemia?
liver
what is the Hb level associated with Beta-thalassemia major (homozygous)?
Hb
what is the Hb level associated with Beta-thalassemia intermedia?
Hb level 7-10
what are some common manifestations seen with Beta-thalassemia major (Cooley’s anemia)?
- fatigue
- jaundice
- hepatosplenomegaly
- dark urine
- bone deformities
- leg ulcers
- cholelithiasis
- stunted growth
- delayed puberty
- cachexia
what is the most severe form of Alpha-thalassemia?
Hydrops fatalis; child dies in utero or shortly after birth
is thalassemia micro, macro, or normocytic?
microcytic
what might you see on a blood smear of thalassemia?
- microcytosis
- hypochromia
- anisopoikilocytosis
- nucleated RBCs
- target cells
why would you do a hemoglobin test if you suspect your patient has thalassemia?
to differentiate what type of Hb chains they have in order to determine their type of thalassemia
what index is used to determine if your patient has thalassemia or iron deficiency?
Mentzer index (MCV/RBC count) > 13 = iron deficiency
what serum level can be used to differentiate between iron deficiency and thalassemia?
ferritin; will be low if iron deficient but normal in thalassemia
how does the MCV differ between Alpha-thalassemia and HbH disease?
Alpha-thalassemia has MCV 65-75 fL
HbH disease has MCV 55-65 fL
how do you treat heterozygotes of thalassemia (carries)?
no treatment really aside form genetic counseling
what is the conventional treatment of thalassemia major and thalassemia intermedia?
regular blood transfusion and iron chelation
which thalassemia may require a splenectomy?
thalassemia major
