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Describe the pathophysiology of aplastic anemia
- Result of decreased hematopoietic stem cells (decreased ability for self renewal, increased cellular destruction)
- Decreased signal for cellular proliferation and differentiation
- No definitive cause is applicable to all causes of aplasia
- >95% acquired, <5% congenital
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Etiology of Acquired Aplastic Anemia
- Idiopathic or primary
- 40-70%
- No definitive cause
- SecondaryChemical agents (benzene, insecticides, weed killers)
- Drugs (chemotherapeutical agents, bulsufan, vincristine, colchicine)
- chloramphenicol
- phenylbutazone
- penicillin
- aspirin
- ionizing radiation (300-500rads are lethal, lesser doeses are reversible; full recovery in 4-6 weeks)
- Infections (hepatitis, Epstein-Barr Virus, cytomegalovirus)
- Micellaneous causes (pregnancy, malnutrition [anorexia], hair dyes [rare])
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Clinical features of Acquired Aplastic Anemia
- Fatigue
- Dyspnea (abnormal breathing in attempt to get O2)
- Palpitations (abnormal heartbeat)
- Infections (no WBC)
- Bleeding (no platelets) (petechiae [small dots], purprua and ecchymoses [large spots], mucosal bleeding)
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What would you find in a Lab examination of Acquired Aplastic Anemia? (peripheral blood values, other tests
- RBC count: markedly decreased
- Hgb: <7 g/dL
- Hct: 20-25%
- normocytic and normochromic
- may show A&P
- reticulocyte count: <1%
- WBC count: usually <1500/μL
- decrease in granulocytes and monocytes
- relative increase in lymphocytes (total amt is less)
- Platelet count: <20,000-60,000/μL
- reduced platelets on smear
- Kidney and liver function tests
- Blood cultures
- Bone marrow may be difficult to even aspirate as the majority is replaced with fat
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Treatment and prognosis of Acquired Aplastic Anemia
- Untreated usually results in death
- Before 1970s treatment: transfusions, steroids, determine etiologic agent
- More recent: bone marrow transplantation (infused into arm, and stem cells "know where to go"); immunomodulatory therapy using antithymocyte or antilymphocyte globulin
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Etiology of Congenital Aplastic Anemia
- AKA Fanconi's Anemia
- ~400 clinical cases described (basically nothing)
- Numerous chr. abnormalities (breakages, defective DNA repair, associated with other hematological abnormalities, acute myelogenous leukemia)
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Clinical features of Congenital Aplastic anemia
- Skeletal defects of thumb
- Cutaneous hyperpigmentation
- Renal abnormalities
- microcephaly
- mental retardation
- poor growth
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Laboratory examination of Congenital Aplastic anemia
- Pancytopenia by age 5-10 years
- Anemia and thrombocytopenia usually precedes leukopenia
- May have increased Hgb F levels and erythropoieten levels
- *note- the stress erythropoiesis pattern
- Poor marrow
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Treatment and prognosis of Congenital Aplastic anemia (Fanconi's Anemia)
- Treatment
- Some patients respond to cytokine or corticosteroid therapy
- Allogeneic or cord blood transplantation
- Prognosis
- Patients usually die from infections or hemorrhage secondary to the pancytopenia
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Information about Pure Red Cell Aplasia
- Uncommon disorder
- Over 600 cases identified
- Selective decrease in RBCs only (erythroid precursor cell)
- WBCs and platelets are unaffected
- Acquired and congenital forms
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Etiology for Pure Red Cell Aplasia
- Infections (viruses)
- drugs
- malnutrition
- chronic infections
- vitamin deficiency in children
- thymoma or lymphoid neoplasms
- idiopathic
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Laboratory findings for Pure Red Cell Aplasia
- Severe, chronic, normocytic to slightly macrocytic anemia
- Decreased reticulocytes (decreased total production of everything)
- no abnormalities with WBC or platelets
- No hemolysis or hemmorhage
- marrow: normal cellularity with noticeable absence of RBC precurors
- 4:1 M:E
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Treatment and prognosis of Pure Red Cell Aplasia
- Usually recover in a few days to weeks if caused by virus, or with removal of offending drug
- Surgery may be required to remove offending tumor
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all information about Congenital red cell aplasia
- AKA Diamond-Blackfan anemia
- May be a molecular defect that prevents RBC precursors from responding to erythropoietin and cytokines
- Physical abnormalities in head and neck (similar to Fanconi's anemia)
- Chronic, moderate to severe, normocytic to macrocytic anemia
- Normal WBCs an platelets
- Steroid treatment and bone marrow transplantation have been successful in treating the anemia
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