Blood And Lymph- Hemolytic Anemia (Continued) By Turnicky

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Blood and Lymph- Hemolytic Anemia (continued) by Turnicky

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Blood and Lymph- Hemolytic Anemia (continued) by Turnicky

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Transfusion and Anemia

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If severe anemia results
-Transfusion will involve incompatible units of blood and should proceed only if clinically mandated
-Presence of alloantibodies must be excluded, however, the autoantibodies may interfere with blood bank tests
-Accurate pt history mandatory:
-Prior transfusion, pregnancy, IV drug use

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What does alloimmune mean? And alloimmune Hemolytic anemia.

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Alloimmune: Antibody formation for foreign antigens (another individual’s red cells)
-Hemolytic transfusion reaction
-Hemolytic disease of the new born

-Antibody induced by immunization by red cells from another individual
-Recipient lacks Ag (s), present on donor red cell
-Donor cells recognized as foreign
-Antibody formation with activity against donor cells

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Hemolytic Disease of the New BornErythroblastosis Fetalis

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-Alloimmune disease associated with fetal RBC destruction during neonatal life due to fetomaternal blood group incompatibility.
-Antibody specificity is usually to Rh or ABO system
-Fetus becomes anemic, develops CHF and indirect Bilirubin may injure CNS
-Mother must be exposed to an RBC antigen that she lacks
-Mother must produce Abs to the foreign Ag
-Mother’s Ab must be able to cross placenta
-The fetus must possess the Ag to which the mother is sensitized

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Hemolytic Disease of the New BornCaused by Rh Incompatibility. Happens for every pregnancy? How do you treat?

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-Mother Rh negative; baby Rh positive
-Only pregnancies after the first are affected
-Fetal-maternal bleed usually after 28wks and IgG Abs titers do not rise before delivery
-Positive DAT, severe anemia and bilirubinemia (on subsequent pregnancies)
-Treat with exchange transfusion
-Therapeutic approach is prophylaxis with Rh immunoglobulin (anti-D Ig) given to first time pregnancies of all Rh negative mothers.

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Hemolytic Disease of the New BornCaused by ABO Incompatibility. Affects every pregnancy? Tx?

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-Mother type O; baby A or B
-First pregnancy and subsequent pregnancies may be affected
-Mild anemia, mild bilirubinemia usually peaking 48 hrs after birth
-Phototherapy as treatment

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What happens in drug-related hemolytic anemias? Three mechanisms...

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-Drug related to antibody production which may cause hemolysis (only one immune mediated)
-Drug induced oxidation of hemoglobin (G6PD deficiency)
-Drug associated with thrombotic microangiopathies resulting in mechanical destruction of red cells (coagulation system)
*oxidized Hb is unstable and precipitates as heinz bodies.
-The drug does not cause direct red cell injury alone
-May also cause immune destruction of platelets, and white cells
-Mechanisms:
-Drug adsorption (hapten –type)
-Immune complex (innocent bystander)
-Membrane modification/Autoantibody induction

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Drug-related Hemolytic Anemias“Drug Adsorption”...what happens, does complement occur? What commonly causes this?

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-Drug/metabolites, too small to initiate an immune response bind to proteins on red cell creating an immunogenic complex with resultant antibody production
-Complement activation does not occur
-Extravascular hemolysis: mediated by Fc receptors
-Penicillin and cephalosporin most common

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Drug-related Hemolytic Anemias“Immune Complex”... is complement activated?

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-Drug/protein(in plasma and not red cell) form neoantigen
-IgG or IgM adsorbed on to the rbc in a nonimmune reaction, but activates C
-Incomplete C3d, extravascular phagocytosis
-Complete C activation; intravascular lysis

*Only requires small amounts of drug

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Drug-related Hemolytic Anemias“Membrane Modification/Autoantibody”

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Drug may cause an antibody that is indistinguishable from an antibody that causes warm autoimmune HA
-Methyldopa prototypical
-Fludarabine same mechanism

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Direct vs Indirect Coombs test

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Coombs test: detects red cells sensitized with Antibody and/or Complement invivo

Direct:The anti-human antibody reacts with patient cells if they are coated; results in cell agglutination

Indirect:Detect antibodies in patient serum (as opposed to antibody on patient cells as in DAT)
Patient serum incubated with red cells of known antigenic makeup.
If suspected serum antibody is present against the target antigen, agglutination occurs
Add AHG, if complex present get red cell agglutination.

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Non Immune HA, Enzyme deficiencies: so glucose is the cell's primary energy producing substrate, catabolized via Embden-Meyerhof or hexose-monophosphate (HMP) shunt...what bad things can happen, and what do you need the shunt for exactly?

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-The energy producing pathways may produce free radicals
-These harmful forms of oxygen can oxidize hemoglobin iron from ferrous (Fe+2) to the ferric non-oxygen binding form (Fe+3)
-HMP shunt, critical for generating reduced glutathione as a cellular antioxidant

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What is the most common enzyme disorder? Who gets it most? What happens? What happens in young RBCs?

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-Glucose 6 phosphate dehydrogenase deficiency. Sex-linked (guys).
-Depletion of glutathione results in irreversible oxidation of Hb (fe+3)
-Hb degradation products polymerize to form Heinz bodies with resultant membrane damage and red cell phagocytosis in the spleen
-Young RBCs have more NADPH and are less susceptible to oxidation, so as reticulocytosis (young rbcs) increases, the effects of low doses of an oxidative drug tend to be self-limiting.

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G6PD clinical... what can make this condition come out? tx?

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Asymptomatic until illness or exposure to certain drugs
-ASA (aspirin), sulfas, anti-malarials*
Intravascular hemolysis with hemoglobinemia/hemoglobinurea.
-Bite cells, spherocytes
-Hemolysis 1 to3 days after drug exposure
-May experience abdominal or low back pain
-Degree of hemolysis is variable and dependent on the degree of oxidant stress
-tx: avoid oxidant drugs; for acute, supportive therapy, including transfusion

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Ok, so what's the second most common enzyme deficiency? Treatment?

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Pyruvte Kinase Deficiency:
-Most common enzyme deficiency in the Embden-Meyerhof pathway
-Deficient conversion of ADP to ATP resulting in
-Rbc potassium leak and membrane deformity
-Sequestration in the red pulp of spleen
-Anemia limited to homozygous state
-Heterozygosity is asymptomatic
Therapy: Transfusion, splenectomy

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Hereditary Spherocytosis is a membrane abnormality, intrinsic defect. What is deficient? What can happen?

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-Common: 1 in 5000
-Deficiency in cytoskeleton spectrin protein
-Cells lack flexibility, trapped in spleen.
-Low glucose conc, cells run out of ATP needed to pump out excess Na+
-Compensated disease, no anemia

Therapy:Splenectomy corrects hemolysis but the basic membrane defect remains and spherocytes can still be found circulating in the peripheral blood.

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So what's so different about hereditary spherocytosis?

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Reticulocyte count >8%
Decreased MCV (77-87 fl)
Normal MCH
Increased MCHC
-***Spherocytes are the only cell to have elevated MCHC**
-Spherocytes also seen in AIHA

**the only HYPERchromic

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What about Hereditary elliptocytosis? Who gets it? what's defective?

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-More common in Blacks but seen in all racial groups
-Defective spectrin chains with increased permeability to Na+
-90% no overt signs of hemolysis

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Paroxysmal Nocturnal Hemoglobinuria (PNH) is a membrane disorder. What is abnormal?

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-Rare acquired disorder (stem cell)
-Abnormal sensitivity to complement lysis
-Intermittent bouts of IVH and nocturnal hemoglobinuria
-Exacerbataed during sleep, remits in day
-Simply a chronic ongoing hemolysis

*More acidodic when you’re sleeping, and complement is more active in acidic environments

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PNH and complement... what is missing?

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-Deficient regulation of complement activation after initial attachment
-Two normal regulators for preventing complement amplification are missing on the rbc membrane:
-CD55: Decay accelerating factor (DAF)
-inhibits formation of C3 convertase
-CD 59: Memb. Inhibitor of Reactive Lysis (MIRL)
- protects membrane form attack by C5-C9 complex

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Ok, so is it really CD55/59 that's missing? Or is it something else?

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Glycosyl-phoshatidyl inositol (GPI):
-Membrane deficiency resulting from an absence of an anchoring protein for both CD55/59.
-Due to an acquired somatic mutation in the PIG gene
-All cell lines are deficient in GPI, with hypersensitivity to complement, with anemia, granulocytopenia and thrombocytopenia

*MISSING THE ANCHORING PROTEIN OF THE COMPLEMENT REGULATORS! Mutation of PIG gene makes you be deficient in the anchoring protein GPI)

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Lab evaluation and therapy for PNH?

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Flow cytometry is the method of choice in identifying the absence of CD55/CD59.
-Labor intensive and costly (Interrogates both granulocytes and red cells)
-In reality not sensitive and many cases are under diagnosed (likely due to transfusion containing cells with normal GPI).

Newer flow method using fluorochrome-conjugated bacterial toxin Aerolysin
-Toxin binds to GPI structure resulting in lysis of normal red cell
-PNH cells lacking GPI do not lyse; Less labor intensive and more sensitive.

Tx: is supportive (transfusion), control hemolysis (short term prednisome, anti-complement therapy), manage thrombosis w/ anticoagulation

*bone marrow the only curative treatment, but there can be spontaneous remission. also do immunosuppressive therapy

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Ok, so is it really CD55/59 that's missing? Or is it something else?

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Glycosyl-phoshatidyl inositol (GPI):
-Membrane deficiency resulting from an absence of an anchoring protein for both CD55/59.
-Due to an acquired somatic mutation in the PIG gene
-All cell lines are deficient in GPI, with hypersensitivity to complement, with anemia, granulocytopenia and thrombocytopenia

*MISSING THE ANCHORING PROTEIN OF THE COMPLEMENT REGULATORS! Mutation of PIG gene makes you be deficient in the anchoring protein GPI)

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Lab evaluation and therapy for PNH?

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Flow cytometry is the method of choice in identifying the absence of CD55/CD59.
-Labor intensive and costly (Interrogates both granulocytes and red cells)
-In reality not sensitive and many cases are under diagnosed (likely due to transfusion containing cells with normal GPI).
Newer flow method using fluorochrome-conjugated bacterial toxin Aerolysin
-Toxin binds to GPI structure resulting in lysis of normal red cell
-PNH cells lacking GPI do not lyse; Less labor intensive and more sensitive.

Tx: is supportive (transfusion), control hemolysis (short term prednisome, anti-complement therapy), manage thrombosis w/ anticoagulation
*bone marrow the only curative treatment, but there can be spontaneous remission. also do immunosuppressive therapy

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Microangiopathic Hemolytic Anemia, an HA due to extrinsic factors is an inclusive term describing a hemolytic process caused by microcirculatory lesions. What are the three most common thrombotic microangiopathies?

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The three most common thrombotic microangiopathies are:
HUS (hemolytic uremic syndrome)
DIC
TTP (Thrombotic Thrombocytopenia Purpura)

*Distinguishing between TTP & HUS may be difficult.
**classing finding in microangiopathic hemolytic anemia is schistocytes.

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What is the tetras of HUS? What age is it most prevalent? Why is there a pathology?

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-Hemolytic anemia with schistocytes
-Acute renal failure
-Thrombocytopenia
-CNS symptoms (seizures)

-In previously healthy kids, highest incidence in first year of life
-Acute onset, pallor, vomiting, bloody diarrhea and macroscopic hematurea.
-Most serious complication: ARF
-Pathology due to thrombosis of the microcirculation (endothelial damage)

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What is seen in 90% of HUS cases? What causes it? Recovery?

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-Diarrhea associated (90%)--infectious
-D+ HUS due to verocytotoxin producing E.coli (VTEC) infection traced to ingestion of incompletely cooked beef, or vegetables contaminated with VTEC.
-2% to 4% will develop HUS
-80% recovery

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D+ vs D- HUS?

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D+ HUS (bacterial toxin)
-E.coli & Shigella

D- HUS (may be due to a mutation in thrombomodulin*)
-Post-partum
-Oral contraceptives
-Viral, drugs, Bone Marrow Transplant

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Pentad of TTP?
who gets this?

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Pentad of clinical findings:
-Microangiopathic HA
-Thrombocytopenia
-CNS Symptoms
-Fever
-Renal Dysfunction

Young adults, more females. but still rare.
Precipitating factors include infection (40%) and pregnancy (10 to 25%)
Without treatment, TTP has a mortality of 90% due to multi-organ failure.

-Hyaline thrombi form in the microvasculature: kidneys, heart, brain, spleen.
-Abnormal vWF multimers bind endothelium and induce platelet aggregation (also HUS?)

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TPP is a disorder in WHAT?! They are missing what?!

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-TTP is a disorder of vWF
-Endothelium secretes vWF in a form that contains unusually large vWF multimers that are normally cleaved by a metalloprotease to smaller vWF multimers.
-This metalloprotease is also referred to as vWF cleaving protease or ADAMTS-13
-Patients with TTP have decreased metalloprotease (congenital or acquired secondary to autoantibody to the metalloprotease)
-Patients with HUS do not have a decrease in metalloprotease

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besides ADAMTS13, how do you differentiate TTP from HUS?

Therapy:

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TTP is clinically similar to HUS except in young adults, more organ systems damaged, neurological symptoms more prominent, renal dysfunction less severe, mortality rate higher.

Therapy:
-Daily plasma exchange or plasma infusion with corticosteroids.
-Splenectomy
-Immune suppression
-Rituxin (anti b cell antibody)

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Ok, let's wrap it up... hemolytic anemia... what is a constant feature in hemolytic anemia?

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-Normochromic Normocytic anemia resulting from premature red cell destruction
-Reticulocytosis is a constant feature (polychromasia on smear)
-Erythroid hyperplasic of BM
-Peripheral Smear Review (poikilocytosis)
-Spherocytes
-schistocytes

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Hemolytic Anemia: Laboratory Findings..what is almost always decreased

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-Decreased haptglobin (almost always)
-Increased serum LDH
-Hemoglobinemia, hemoglobinurea
-Increased unconjugated (indirect) Bilirubin
-Jaundice, gallstones consisting of bilirubin
-Normal conjugated (direct) Bilirubin