Red Cell Disorders 2 Flashcards
What type of hemolysis is seen in thalassemia? What is the cause of this in β thalassemia?
Extravascular hemolysis; this is caused by the excess of unimpaired chains so in β thalassemia it would be do the the excess of α chains that precipitate
α thalassemia will ↑/ ↓ sickling
↓ because thalassemia is a ↓ in the Hb concentration
What is the presentation of the RBC’s in someone with thalassemias?
- microcytic hypochromic RBC’s
HbS molecules have a tendency to aggregate and polymerize when ______
Deoxygenated; so occurs when they drop off oxygen in the tissues
β thalassemia major is characterized by the absence of ____
Normal β globin gene
β0/ β0, β+/β0, β+/ β+
Leg ulcers in sickle cell patients most common occur in the _______
Medial or lateral malleolus
in β0 thalassemia, there is NO β chains produced due to nations in ______
Splicing or chain termination
In sickle cell, the bone marrow becomes _______ leading to ______
Hyperplastic bone marrow —> changes in bony skull
Autosplenectomy in patients with ________ can make patients prone to infections by ______________
HbS; capsulated infections from H. Influenza and S. Pneumonia
What are the different types of crises seen in sickle cell?
- vaso-occulsive crisis
- sequestration crisis
- aplastic crisis
- hemolytic crisis
β+ thalassemia is reduced β chain synthesis due to mutation in what region?
Promoter region
describe the mutation that results in sickle cell anemia
- point mutation at position 6 in the β globin chain: glutamic acid → valine
Describe the manifestation of sequestration crises in sickle cell
Massive entrapment of sickle RBC’s in the spleen —> splenomegaly, and hypovolemia/shock
What can you expect to see on a histopathological slide of the spleen in someone with sickle cell?
They sinusoids will be congested with RBC’s with pale areas with fibrosis.
If fibrosis continues can lead to autosplenectomy
The extravascular hemolysis in thalassemia syndromes is due to _______
The excess of unimpaired normal chains will aggregate causing insoluble inclusions
Sickle crises can be precipitated by: (5)
- exposure to cold
- hypoxia
- infections
- dehydration
- acidosis
Cardiac failure in β thalassemia is due to __________
- high output failure (severe anemia)
- iron overload (cardiomyopathy)
Vaso-occulsive crisis in sickle cell most commonly affects the _____________ leading to _____
Bone; hand foot syndrome aka dactylitis which is due to blocked blood circulation
hemoglobin defects can be classified into :
- hemoglobinopathies aka production of defective Hb: sickle cell, Hb C disease
- thalassemia syndromes aka decreased synthesis of globin chains of HbA
Infection by parvovirus B19 is involved in _________ crisis in sickle cell patients
Aplastic
In addition to an enlarged spleen and liver, what are some other manifestations of thalassemias?
- ineffective erythropoiesis —> explosion of hematopoietic marrow leading to prime time facial bones and erosion of barony cortex and new bone formation
- iron overload due (hemosiderosis or secondary hemochromatosis) to excessive dietary iron absorption and regular blood transfusions
Mixing of a sickle cell patient’s blood with _____ is used as a screening test for sickle cell disease
Metabisulfite which is an oxygen consuming agent that induces sickling
In aplastic crisis, there is a transient cessation of ______ due to _______
Erythropoiesis leading to worsening of anemia due to red cell progenitors being infected by parvovirus B19
Sickle cell disease can increase the risk for an individual developing what type of renal carcinoma?
- renal medullary carcinoma
what are some factors that induce sickling in sickle cell disease?
- presence of HbC
- dehydration
- ↓ pH
- exposure to low O2 tension
