thalassemias and sickle cell Flashcards
What are the types of alpha thalassemia?
- problem with production of alpha hemoglobin chains, which is determined by 4 genes:
1. alpha-thalassemia minima: 1 abdnormal gene, usually asymptomatic
2. alpha thalassemia minor: 2 abnormal gnes, mild anemia, microcytic RBCs and target cells on blood smear
3. hemoglobin H disease: 3 abnormal genes, minimal alpha globin production, chronic hemolytic anemia, splenomegaly, hemoglobin H in blood
4. 4 defective genes. lethal in utero
What are the beta thalassemias?
minor: 1 defective gene that leads to reduced beta-globin production, mild anemia, increased hemoglobin A2. Pts may live normal lives, but might require transfusions during times of stress
major: 2 defective genes: asymptomatic until decline of fetal hemoglobin. pts have growth retardation, developmental delays, bony abnormalities, hepatosplenomegaly, anemia. pts die in childhood without chronic transfusions
What is hemoglobin bart?
hemoglobin without alpha chains- hemoglobin can bind O2 but is unable to release it
Where is the defect in sickle cell anemia?
defect in the beta globin chain of hemoglobin, leading to the production of abnormal hemoglobin S (normal valine replaced with glutamic acid in disease state)
What is the difference between beta thalassemia and sickle cell anemia?
- both involve beta chains of hemoglobin
- sickle cell: abnormal beta chain production
- beta thalassemia: reduced amount of normal beta chains
What are radiographic findings of sickle cell disease?
“fish-mouth” vertebrae, lung infiltrates in acute chest syndrome
What prophylactic medications are indicated for sickle cell disease?
hydroxyurea, pneumococcal vaccine in asplenic pts, prophylactic penicillin for kids until age 5 to reduce pneumococcal infection
What kinds of organisms are especially dangerous to sickle cell patients?
salmonella osteomyelitis, encapsulated organisms (strep pneumo, haemophilus, neisseria meningitis, klebsiella), group B strep, some e Coli
What are some causes of eosinophilia?
Addison’s disease, neoplasm, asthma, allergy, collagen vascular disease, transplant rejection, and parasitic infection
What are causes of agranulocytosis?
clozapine, antithyroid meds, sulfasalazine, methimazole, TMP-SMX, chemo, aplastic anemia
What are type 2 hypersensitivity reactions?
mediate by IgG and IgM antibodies. cellular antigens react with antibodies to initiate complement cascade and cell death, as in drug induced or immune hemolytic anemia, hemolytic disease of the newborn, rheumatic fever, goodpastures, bullous pemphigoid and pemphigous vulgarous
What are type 3 hypersensitivity rxns?
mediated by IgG and IgM immune complexes. antibodies bind to antigens and make complexes that are deposited in tissue. think serum sicknus, arthus rxn (swelling after tetanus vaccination), SLE, polyarteritis nodosum)
