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18 Cards in this Set
- Front
- Back
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What is anemia?
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A pathological deficiency in the oxygen-carrying component of the blood, measured in unit volume concentrations of hemoglobin, red blood cell volume, or red blood cell number.
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Lab Values of Hemoglobin Male vs. Female
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Hematogrit Lab Values Male vs. Female
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Hematocrit(Hct)
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What is the Mean Corpuscular Volme (MCV)
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Mean corpuscular volume (MCV)
86 –98 μm3/cell |
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Basics of Sickle Cell Anemia
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Sickle cell anemia is inherited form of anemia
-Red blood cells (RBC) become rigid and sticky and are shaped like sickles or crescent moons -These irregular-shaped RBC die prematurely -Results in chronic shortage of RBC -They also get stuck in blood vessels and slow or block blood flow and oxygen = pain + complications -No cure for most people |
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Sickle Cell Trait versus Sickle Cell Disease
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Sickle cell trait
-Have one gene for the disease -No signs and symptoms -Don’t develop the disease unless exposed to low oxygen -Approximately 1 in 12 black Americans ________________________ Sickle cell disease -Have two genes for the disease -Show signs and symptoms after 4 months of age -Some people have mild symptoms -Others have severe symptoms and need frequent hospitalization. |
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Signs & Symptoms of SCA
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-Anemia –sickle cells very fragile
-Pain episodes (crises) –sickle-shaped RBC block blood flow through tiny blood vessels -Hand-foot syndrome –swollen hands and feet often first sign of disorder in babies -Jaundice –liver overwhelmed by rapid breakdown of RBC -Frequent infections –sickle cells can damage spleen -Stunted growth –due to lack of oxygen and nutrients needed for growth -Vision problems |
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What causes SCA
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Mutation in gene responsible for making hemoglobin
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What is the disease etiology?
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Autosomalrecessive disorder of Hgb
-Missensemutation causes an amino acid substitution (valinefor glutamine) -Prevalence variable among populations -Mutation evolved to confer resistance to malaria and thereby provided a survival advantage to heterozygotes(Heterozygote Advantage) |
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Evolution of Defective Gene
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Sickle cell anemia evolved many years ago in Africa, Mediterranean, Middle East, and India
-Malaria epidemics were rampant -Some people developed a genetic mutation that caused RBC to change shape -These sickle cells interfered with growth of parasite (Plasmodium) that causes malaria -Sickle cell trait allowed some to survive malaria outbreaks |
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Novel Property Mutation
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A change in the amino acid (glufor val) sequence confers a novel property on the protein (Hgb) that results in a disease (sickle cell anemia)
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What is the pathogenesis of the disease?
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The amino acid substitution (valfor glu) causes a decreased solubility of deoxygenated Hgb
-This Hgbpolymerizes, forming a gelatinous network that stiffens and deforms the cell -These cells occlude capillaries causing infarctions and tissue injury distal to that site -Normal RBCslive 90 to 120 days -Sickle cells die after 10 to 20 days -Chronic RBC shortage = anemia |
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What is the inheritance risk?
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Future children of an affected person have a risk dependent upon the genotype of the other parent
-Future sibs of an affected patient have a 25% chance of HgbSdisease and 50% chance of HgbStrait |
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Inheritance Risk
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In the United States
80,000 Americans have the disease -1 in every 500 African American births -1 in every 1000 Hispanic births __________________________ Two million Americans have the trait -1 in 12 African Americans -50% chance of being a carrier -25% chance of having the disease |
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Complications
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-CVA (cerebral vascular accident) or stroke
-Acute chest syndrome -Chest pain, fever, difficulty breathing -Caused by lung infection or trapped sickle cells in lungs -Antibiotics, blood transfusions, and bronchodilators -Organ damage -i.e., kidneys, liver, spleen |
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Other Complications
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-Leg ulcers
-Gallstones due to high bilirubinfrom RBC breakdown -Priapism |
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What is the treatment?
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-Bone marrow transplant offers potential cure
-Few people have suitable donor -Treatment usually aimed at avoiding crises -Antibiotics –children take penicillin until 5 years -Pain meds -Hydroxyurea–appears to stimulate fetal Hgbthat helps to prevent sickle cell formation -Long-term use may lead to leukemia or tumors -Blood transfusions –increase normal RBC but can cause excess iron accumulation -Supplemental oxygen |
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Experimental Treatments
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-Gene therapy –correct defective gene and insert into bone marrow
-Butyric acid –may increase fetal Hgb -Clotrimazole–prevents water loss from RBC which may reduce number of sickle cells -Nitric oxide –helps dilate blood vessels and reduces stickiness of RBC; may also prevent formation of sickle cells |
