Hematology II Week 2 obj: Immune Vs. Non-Immune Hemolytic Anemia
sample collection for PCH
2 tubes are collected and incubated at 4 C for 30 mins and again at 37C for 30 mins. (to allow full complement lysis)
acute hemolytic transfusion rxn
ABO incompatible donor rbc recipient occurs within minutes to hours of the transfusion
DAT test
DAT (direct anttihuman globin test or Direct Coombs test) used to detect if C3d is presence (C3d is attached to rbc membrane)
organisms that can cause hemolytic anemia
Malaria: an infection of rbcs with protozoan parasites (plasmodium) Babesiosis: a tick transmitted disease cause by intraerythrocytic protozoan parasite (intravascular) Bartonellosis: carrion disease, transmitted by female sandfly Clostribium perfringens: normal flora of the GI tract, but can be life threatening (intravascular)
Drug-induced hemolytic anemia: drug rbc membrane protein immunogenicity complex
a drug binds to an rbc membrane protein to form a drug rbc protein immunogenicity complex (epitope). the pt produces an IgM or IgG ab that binds to the complex on the rbcs and complement is fully activated which causes intravascular hemolysis
drug induced: rbc auto-antibody induction
a drug induces the pt to produce IgG warm reactive auto antibodies against rbc self antiens. they react at 37C and hemolysis occurs extravascular by macrophages in the spleen
Drug induced: drug dependent auto-antibodies
ab that react only in the presence of the drug. IgG or IgM ab will bind the drug and extravascular hemolysis will occur
detection of sensitized rbcs: agglutination in saline
agglutination occurs = rbc is coated with antibodies (immune hemolytic anemia) no agglutination = non immune hemolytic specifically for IgM
Warm agglutinin syndrome
an autoimmune hemolytic anemia IgG antibodies binds to rbc at warm temperatures (37C), can activate complement. hemolysis: extravascular
alloimmune
an immune response to non self antigens ex: transfusion
autoimmune
an immune response to self antigens, that causes premature rbc destruction and anemia. caused by auto-antibodies that binds to the rbc membranes with or without complement activation.
DIC lab findings
blood smear: thrombocytopenia, shistocytes abnormal coagulation: increased D Dimer, FDS decreased fibrinogen due to low plt count APTT, TT, PT prolonged
Sensitized RBCs
cells that antibodies attached to the rbc membrane
PCH (Paroxysmal Cold Hemoglobinuria) lab findings
decreased hgb hemoglobinemia hemoglobinuria methalbuminemia neutropenia, reticulocytopenia spherocytes increased bilirubin decreased haptoglobin
Cold Agglutinin Syndrome
is an autoimmune hemolytic anemia. IgM antibody binds to rbcs after exposure to the cold (below 30C). IgM ab can activate the classical complement pathway. hemolysis: extravascular
physical causes of hemolytic anemia
malignant hypertension cardiac prothesis march hgburia
excerise induced hemoglobinuria
mechanical trauma from forceful and repeated impact of the body on hard surfaces can cause rbc lysis
Hemolytic uremic syndrome (HUS)
non immune hemolytic anemia caused by a triad of d/o (hemolyic anemia with rbc fragments, thrombocytopenia low plt count, acute nephropathy acute renal failure) intravascular
Thrombotic Thrombocytopenia Purpura (TTP)
non immune hemolytic anemia caused by auto ab mediated, which it inhibits the enzyme ADAMTSI3 (Von Willebrands Factor enzyme) which causes clots to form in the blood vessel resulting in low plt count and organ damage. plts are not normal, causing large clumps of clots in the blood intravascular
Disseminated Intravascular Coagulation (DIC)
non immune hemolytic anemia normal coagulation altered due to underlying conditions: bacterial spesis, neoplasms, immunologic d/o or trauma intravascular
microorgangiopathic hemolytic anemia (MAHA)
non immune hemolytic anemia occurs intravascular anemia caused by the mechanical shearing of rbc membranes as the cells pass through small blood vessels.
HUS lab findings
normocytic normochromic (shistocyts, helmet cells, spherocytes) polychromasia, plt count low hemoglobinemia/hgburia bili/LD increased, haptolobin decreased BUN, creat, hypokalemia/hyponatremia increased
TTP lab findings
normocytic, normochromic polychromasia shistocytes bili/LD increased decreased haptoglobin
delayed hemolytic tranfusion rxn
occurs days to weeks after transfusion as the titer of the alloantibody increases IgG reacts at 37C ex: previous transfusion
hemolytic disease of the fetus and newborn
occurs when IgG alloantibody produced by the mother and crosses the placenta into the fetus circulation. which binds to the fetal rbcs and causes lyse. ex: RH factor
CAIHA (cold autoimmune hemolytic anemia) Lab findings
positive DAT normocytic, normochromic false increase in MCV, MCH, MCHC increased retics spherocytes agglutinated rbcs, rouleaux nrbcs increased bilirubin decreased haptoglobin
WAIHA (warm autoimmune hemolytic anemia) lab findings
positive DAT normocytic, normochromic increased retics spherocytes presence of auto-antibodies in serum increased bilirubin decreased haptoglobin
RBC zeta potential
serves as an important parameter in characterizing the electrostatic interaction between particles
detection of sensitized rbcs: antihuman globulin (AHG) or Coombs test
specifically for IgG or complement
paroxysmal cold hemoglobinuria (PCH)
the anti P autoantibody (Donath-Londsteiner antibody) IgG has a specifity to P antigen on the rbc membrane. at cold temperatures anti P auto-antibody binds to the P antigen on the rbc. it will partially activate the complment pathway (C1-C4) at 37C (warm) C3-C9 is activated (full complement) hemolysis: intravascular
Drug-induced hemolytic anemia: Drug absorption
the patient produces an IgG ab to a drug, the drug then binds to the rbcs and hemolysis occurs extravascularly by macrophages
other causes of hemolytic anemia
venom from snakes, spiders, bees or wasps burns: heat breaks down rbc membrane
sample collection for a cold agglutination
whole blood collected in an EDTA lavender top tube, must be warmd up to 37C for 15 mins before testing. (or 30 mins)
