EXAM 3 - Blood Disorders Flashcards
Sickle Cell Anemia
Autosomal recessive disorder, manifests with sickle or crescent shaped RBCs. D/T abnormal type of hemoglobin (hemoglobin-S).
High freq. in mediterranean and African populations
1 in 12 African Americans carry gene for SCA, have sickle cell TRAIT
Sickle Cell characteristics
Sickled cells get “sticky” and stick to walls of endothelium
CAUSES SICKLE SHAPE:
Hemoglobin-S can also cause vasodilation, Acid build up, low O2 and high CO2
Exercise/Cold temps can also cause hemoglobin-S to sickle
Trait for Sickle cell - means they are a carrier:
Genotype is: Heterozygous (40% hemoglobin-S)
SCA the disease - then they are Homozygous recessive and 80-90% hemoglobin-S
Greater concentration of Hemoglobin-S, greater the sickle of RBCs
In Utero - Hemogloubin-F (after 5-6 months) replaced by genetic hemoglobin (could be hemoglobin-S, can take drugs to delay this process)
Hereditary Patterns
NOT sex linked - if one parent has the the disease, the child will have trait regardless.
If one parent has disease and other has trait, 50% chance child will have disease
Pathophysiology of SCA
Lifespan of sickle cell is 15-20days
RBCs with Hemoglobin-S:
rough textured, rigid, elongated crescent shaped RBC
Occurs under conditions of low O2, exercise, dehydration, acidosis, infection (esp. bacterial) stress, anxiety, fever, exposure to cold, high altitudes
Sickle Cells get STUCK and O2 delivery is reduced. Body not getting enough O2.
Process reversible at first, but becomes permanent d/t entrapment by macrophage system of LIVER and SPLEED
Results in hemolytic anemia: increased destruction of RBCs resulting in deficiency of hgb
Manifestations of SCA
More jaundiced
Sclera yellow and urine dark from bilirubin
Painful crises - vascular occlusion from obstruction of cells, no O2 getting around!
more likely to occur: where blood flow is slowest (liver and spleen, medulla of kidney)
In tissue with high metabolic rate (brain and muscle)
Manifestations of SCA pt II
Hypoxia
Intense pain
Serious bacterial infections d/t inadequate splenic filtering of microorganisms
splenomegaly as spleen removes dead blood cells
Diagnosis: SCA
Infants: Asymptomatic 4-6 months d/t fetal hgb
Newborn screening for Hgb pathies are used to ID high risk individuals
Stained blood smear shows sickled cells
Prenatal testing ID presence of homozygote state of fetus
serial blood tests demonstrate decreased hct, hgb and rbc
hgb electrophoresis is used to ID presence of hgb-S and confirm disease
Treatment of SCA
Genetic Disease - NO CURE - bandaid approach
Symptomatic - no compound to reduce or stop, no diet, vitamin or iron therapy
Pain relief requires narcotic analgesics
increase hydration
prophylactic antibiotics
HYDROXYUREA (given to babies with hgb-s) increase solubility of hgb-S (makes less likely to sickle)
Transfusions
pneumovax vaccinations
bone marrow transplant
genetic counseling
avoid precipitating factors
Complications of SCA
Vaso-occlusive events : Tissue infarction, pain and disability
Splenic Sequestration: Hypovolemia, shock, death
Stroke: Weakness, seizures, inability to speak
Aplastic crisis: bone marrow temporality stops erythropoiesis
Avascular necrosis: long bones in leg or arm, hip replacement
Males: priapism - painful prolonged penile erection lasting hours, days, weeks d/t stasis and occlusion, results in impotence
Sickle C Disease (another form of SCA)
Recessive Autosomal
onset later in life, less severe painful crisis, occur less frequency
50% have episodes of abdominal or musculoskeletal pain before age 10 and moderate anemia
also have increased risk for infection, fever
complications of ANY sickle cell disease
Splenomegaly
Cardiomegaly
Acute chest syndrome - atypical pneumonia resulting from pulmonary infarction
Sickle retinopathy - blindness from retinal detachment
decreased vision at 20-30 y/o
during pregnancy - sever bone pain crisis and high incidence of abortions, stillbirths and neonatal deaths.
Hemophilia A
“Classic Hemophilia” 80%
VS.
Hemophilia B “Christmas Disease” 20%
(determines which CLOTTING FACTOR is affected)
very rare to find affected FEMALE
severity:
Mild - 6-30% normal Factor VIII
Moderate: 2-5% normal factor VIII
Severe: <1% normal factor VIII, these rarely survive childhood, life in pain, immobile, isolated
Hereditary, sex-linked recessive disease resulting in a deficiency of factor VIII
Hereditary Patterns
Males cannot be carriers - bc the trait is on the X chromosome
Manifestations of Hemophilia A
Spontaneous of excessive bleeding
- severe episodes by minor trauma
- fatal intracranial hemorrhages with minor head bumps
- deep hematomas, compartment syndrome (bleeding in muscle)
- hematuria, hematemesis, tarry stools
Classic Manifestations = Hemarthrosis (bleeding in joints)
-joint swelling, pain, degenerative changes, limited ROM, permanent disability esp in elbows, knees, ankles
Hemophilia A Diagnostics and Treatment
Prolonged PTT (partial thromboplastin time)
measurement of Factor VIII decreased
prenatal testing
TREATMENT:
Factor VIII from fresh frozen plasma concentrate of cryoprecipitate
Hemophilia A Complications
intracranial hemorrhage
infection with HIV
surgery extremely risky, even dental extractions
Factor VIII > 30% during and until healing occurs
Platelets
90% of coagulation disorders r/t platelet dysfunctions
(Platelet storage in spleen)
platelets are first line of defense against accidental blood loss
normally circulate for 8-10days then destroyed by macrophages in liver and spleen
at any one time, 1/3 are in slow transit in the spleen and do not figure in the platelet count
Platelets Pt II
Normal count: 150,000-400,000 cells/ uL (higher if you do not have a spleen)
Stress = release of epinephrine = splenic contraction = release of platelets into circulation
platelet count low in ppl with enlarged spleens d/t increased trapping in slow transit or macrophage destruction
PETECHIAE are classic manifestations of low platelet count d/t loss of normal endothelial plugging (not always bc of hemorrhage)
Spontaneous hemorrhages (severe) are rare unless platelet count is < 20,000
Quantitative platelet disorders: Thrombocytopenia
Not enough platelets (low count)
Cause:
decreased or defective production in bone marrow
Decrease survival, increased destruction outside the bone marrow caused by underlying disorder
Sequestration - pooling of blood in spleen or increased amount of blood in a limited vascular area
intravascular dilution
blood loss - hemorrhage
Idiopathic Thrombocytopenia Purpura
Most common type of low count - cause unknown
AUTOIMMUNE process
Spleen becomes site of immunoglobulins against platelets and increased phagocytosis
TWO FORMS:
Acute - post viral Thrombocytopenia (children btwn 2-6)
Chronic - essential of autoimmune Thrombocytopenia usually adults <50 (esp. women age 20-40)
Manifestations of Thrombocytopenia
Petechiae - small spots of subcutaneous bleeding
Purpura - larger area of subcutaneous bleeding
Ecchymosis (bruise) - area of subcutaneous bleeding, with color changes
Menorrhagia - excessive menstruation
Bleeding - can happen anywhere
Quantitative platelet disorders: Thrombocytopenia Pt II
In children, usually preceded by viral infection, acute and usually resolves spontaneously
Therapeutic support:
- platelet transfusions
- corticosteroids
- protect from trauma
Other causes of Thrombocytopenia
Chronic alcoholism
HIV
Radiation
In NEONATE:
maternal drug ingestion
syphilis
viral infection
LIVER CIRRHOSIS - enlarged spleen, bad blood flow
Lymphoma:
Cancer of lymphoid tissue, enlarges spleen 80% oh total platelets trapped in spleen.
Metastatic Cancer:
infiltration of bone marrow
Drugs know to decrease platelets
Chemotherapy
thiazide diuretics
Gold
ASA
Heparin
Methyldopa
