Chapter 14 Red Blood Cell and Bleeding Disorders Flashcards
What is anemia?
-reduction of the total circulating red cell mass below normal limits
How does anemia present?
- weakness, malaise, easily tired
- hypoxia can cause fatty change in liver, heart and kidney
What are anemias of blood loss?
loss of intravascular volume
it takes 5 days for CFU-Es to mature
fluid rapidly replenishes from interstitial fluid
What is a complication of early blood loss recovery?
Thrombocytosis (increase in platelet production)
Hemolytic Anemias share what three features?
1-shortened red cell life below 120 days
2-elevated erythropoietin
3-build up of hemoglobin breakdown products from hemolysis
What are the main clinical features of extravascualr hemolysis?
anemia, splenomegaly, and jaundice
Does haptoglobin increase or decerease in hemolytic anemia? What does it do?
decreases because it binds to the free hemoglobin that overflows from macrophages doing the lysing of red blood cells
What is intravascular hemoylsis?
hemolysis from physical damaged like from a parasite
What are the manifestations of intravascular hemolysis
anemia, hemoglobinemia, hemoglobinuria, hemosiderinuria, and jaundice
What is Hereditary Spherocytosis?
- inherited disorder of intrinsic defect in the red cell membrane skeleton
- renders cells spheroid and less deformable increasing their chances to break or become lodges in the spleen
What is the pathogenesis of Hereditary Spherocytosis (HS)?
- Spectrin dimer self associates into a tetramer
- Ankyrin binds spectrin
- Glycophorin A binds spectrin
How does HS clinically present?
- Diagnose on: Family History, labs, blood findings
- 2/3 of patients are sensitive to osmotic lysis w/ hypotonic salts
- HS red cells have increased mean cell hemoglobin concentration
- anemia, splenomegaly, and jaundice
What is the danger of parvovirus?
- may cause aplastic crisis b/c it lyses red blood cells and shuts off RBC production for about 2 weeks
- transfusion may be needed to help patient live
Hemolytic Disease Due to Red Cell Enzyme Defects: Glucose-6-Phosphate Dehydrogenase Deficiency is defined as what?
-abnormalities in the hexose monophosphate shunt or glutathione metabolism resulting from deficient or imparied enzyme function reduce the ability of red cells to protect themselves against oxidative injuries and lead to hemolysis
G6PD is supposed to do what?
- reduce NADP to NADPH
- NADPH is supposed to convert oxidize glutathione to reduce glutathione
What populatio has a higher incidence of G6PD deficiency?
places where malaria is an issue (plasmodium flaciparum)
________ hemolysis is characteristic of G6PD deficiency that can be triggered by infections, microaggressions, and donald trump
episodic
What bodies are found with G6PD?
Heinz bodies which are membrane bound bodies
What is Sickle cell anemia?
a point mutation in the sixth codon of B-globin (glutamate for valine) that promotes the ploymerization of deoxygenateed hemoglobin leading to RBC distortion, hemolytic anemia, microvascular blockage, and ischemic tissue damage
How does sickle cell protect against malaria?
- Sickle cells cant be infected
- malaria lowers INTRAcellular pH causing the cell to sickle
- sickled cells are readily cleared more easily by spleen and liver
- sickled cells prevent PfEMP-1 knobs from adhering cells to epithelium
Heterozygotes of sickle cell on sickle when?
they experience hypoxia
What interfers with the sickle of cells?
HbF stops HbS from sickling cells until a child is bout 5 years old
What factors help sickle blood?
- HbS concentration
- Intracellular pH drop
- Increased transit time through kidney
How does sickle cell present clinically?
- moderate to severe hemolytic anemia
- episodes of hypoxic injury and pain–bones, penis, brain, spleen (pain more common in kids)
- presence of irreversible sickled cells
- sausage fingers and toes (dactylitis)
- reticulocytosis
- hyperbilirubinemia
Acute chest syndrome is what?
- dangerous type of vaso-oclusive crisis in the LUNGS
- fever, cough, chest pain, pulmonary infiltrates
What is priapism?
-prolonged erection associated with 45% of sickle men after puberty
What is Sequesteration crisis?
happens in kids with intact spleens
spleen gets blocked leading to hypovolemia
What is aplastic crisis?
-parvovirus B19 lysing RBCs and shutting off RBC production for 2 weeks
Chronic subtle hypoxia can cause what?
stunted growth and development of body and organs
Asplenia leads you at risk of what infections?
- capsulated organism infection
- Penumococcus pneumoniae
- Haemophilus influenzae
What are thalassemia disorders?
- autosomal dominant
- spikey hair crew cut bone on xray
- deficit of HbA hemoglobin synthesis
- alpha/beta mutation = reduced hemoglobin synthesis
- microcytic hypochromic anemia is the end result
- RBC membranse unstable = lyse = ineffective hematopoiesis = extravascular hemolysis
Whats the pathogenesis of B-Thalassemia?
- mutation that diminish synthesis of B-globin chanins
- can be beta0 or beta+
- beta0 = no globin synth (chain terminator/splice mut)
- beta+ = reduced globin synth (promoter/splice mut)
- splicing mutation is the most common
How does B-Thalassemia present?
- if have two B alleles patient is transfusion dependent AKA termed thalassemia major
- if have one B allel patient has mild asymptomatic microcytic anemia AKA thalassemia minor
What is alpha-Thalassemia?
-inherited deletions that result in reduced or absent synthesis of alpha-globin chains
What are the clinical syndromes for alpha-thalassemia?
- each of the four alpha-globin genes contribute 25%. the more that are mutated the worse it is
- Silent carrier state = asymptomatic w/ microcytosis
What is the alpha thalassemia trait?
- 2 alphas are deleted
- asians have 2 a’s deleted on 1 chr = symptoms
- blacks have 1 a’s deleted on 2 chrs = asymptomatic
- HbA lvls normal to low
- small red cells (microcytosis)
- minimal to no anemia
What is hemoglobin H disease?
- 3 a’s are deleted
- creates HbH = high O2 affinity
- leads to hypoxia
- HbH = RBC inclusions = spleen kills RBCs = severe anemia
What is Hydrops Fetalis?
- all 4 a’s deleted
- fetus in trouble by 3rd trimester
- death or life long dependence on transfusions
- hematopoietic stem cell transplant may be curative
What is paraoxysmal Nocturnal Hemoglobinuria (PNH)?
- X-linked Mutations inactivate PIGA
- GPI-linked proteins are deficient b/c of the mutation
- an enzyme that is essential for the synthesis of membrane bound proteins
- only hemolytic anemia caused by genetic defect
What are the CD markers for paraoxysmal nocturnal hemoglobinuria (PNH)?
decaying factor CD55
lysis inhibitor CD59
C8 binding protein CD59
Red blood cells deficient in CD55, CD59, and C8 are prone to what?
cell lysis
What is the leading cause of death in PNH patients?
- thombosis on the venous variety
- 10% progress to acute myeloid luekemia
How is PNH diagnosed?
flow cytometry which detects deficiencies in GPI-linker proteins such as CD59
What reduces the C5a complement pathogenesis of PNH?
Eculizumab stops conversion of 5 to 5A
What do cells lyse at night in PNH?
- the blood pH drops slightly during sleep which increases the activity of complement
- loss of heme in pee = iron deficiency = anemia
Prognosis of PNH?
Good, can be cured with hematopoietic stem cell transplant
What are immunohemolytic anemias?
-antibodies bind to RBCs leading to their destruction
How are immunohemolytic anemias diagnosed?
detection of antibodies and/or complement on red cells from the patient
-Use direct Coombs antiglobulin test
What the indirect Coombs test do?
- patients serum tested for its ability to applutinate commercially available RBCs bearing particular defined antigens
- used to determine antigen target
- used to determine temp dependence of antibody
Cold agglutinin antibodies active under 37 degrees?
IgM
mono, mycoplasmal infxn
chronic–lymphoid neoplasms
chronic–idopathic
Warm agglutinin antibodies active above 37 degrees?
IgG
primary–idiopathic
secondary– autoimmune, drugs, lymphoid