Hemolytic Anemias Flashcards by Melissa McCormick

hemolytic anemia definition

conditions in which there is an increased destruction of RBCs causing the BM to respond by accelerating production
RBCs destroyed faster than BM can produce them

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Wintrobe classification of hemolytic anemias

normocytic, normochromic

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general lab findings of hemolytic anemias

normo, normo anemia
reticulocytosis, increased IRF
marked polychromasia &amp; NRBCs
elevated indirect/unconjugated bilirubin
normal direct/conjugated bilirubin
decreased haptoglobin (intravascular)

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general signs & symptoms of hemolytic anemias

jaundice: from increased bilirubin production
gallstones made of bilirubin
dark or red urine due to excretion of plasma hemoglobin (or increased urobilin)
splenomegaly (extra)
general anemia symptoms

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Extravascular hemolysis general

RBC destroyed outside blood vessels (spleen (!), liver, BM)
phagocytized by macrophages in the spleen & liver
SPHEROCYTES

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Intravascular hemolysis general

destruction of defective RBCs as they circulate
release hemoglobin into the plasma
decreased haptoglobin 
hemoglobinuria, hemoglobinemia etc
SCHISTOCYTES

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normal way RBCs are broken down

globin is returned to amino acid pool
iron is separated & stored
protoporphyrin (heme ring) is broken down into bilirubin (indirect/unconjugated)
travels to liver via albumin & is converted to conjugated/direct
secreted as bile & dumped into GI tract where is converted to urobilinogen
majority excreted in stool some reabsorbed and excreted in the urine

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intrinsic defects (categories)

membrane
enzymes
hemoglobin
most are hereditary & usually extravascular hemolysis

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extrinsic defects general

antagonist in plasma or soluble factors in environment - toxic to cell & cause hemolysis
physical/mechanical trauma
immune mediated
usually acquired

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Hereditary Spherocytosis (HS) general

hereditary hemolytic anemia due to RBC membrane defect
most common inherited anemia among whites
RBCs deficient in spectrin (secondary deficiency in ankyrin)- loss of membrane, decreasing surface to volume ratio = SPHEROCYTES

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Lab diagnosis of HS

normo, normo
mild anemia
spherocytes (!)
elevated MCHC (due to spherocytes)
reticulocytosis
increased osmotic fragility!! (confirmatory test)

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Osmotic fragility test

RBCs are incubated in varying concentrations of hypotonic NaCl solutions
spherocytes are unable to expand as much & are lysed at a higher concentration of NaCl than normal
confirmatory test for hereditary spherocytosis

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Treatment for HS

mild forms - no therapy

splenectomy

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Hereditary Elliptocytosis (HE) general

hereditary hemolytic anemia due to RBC membrane defect
deficiency of alpha-spectrin or beta spectrin are common
90% of patients show no signs of hemolysis

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populations with HE

Blacks, equatorial african populations

rare in western populations

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laboratory diagnosis of HE

normo, normo
no anemia, no hemolysis (!!)
elliptocytes (usually more than 25%)

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Hereditary pyropoikilocytosis (HPP) general

severe subtype of HE
primarily seen in blacks & arabs
severe hemolytic anemia & extreme poikilocytosis
decreased thermal stability of RBCs
2 defects: deficiency of alpha-spectrin & another mutant spectrin = cell destabilization

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clinical findings of HPP

present at birth
hemolytic anemia
hyperbilirubinemia
splenectomy
striking poikilocytes
decreased MCV (25-55)
increased thermal sensitivity test

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Hereditary Stomatocytosis general

rare! abnormalities in cation permeability in RBC membrane
[intracelluar cations] increases & water enters the cell & overhydratess = stomatocytes
increased bilirubin, moderate reticulocytosis

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Energy for mature RBCs

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dependent on anaerobic glucose metabolism (no organelles)

Glucose-6-phosphate dehydrogenase deficiency ( G6PD) general

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worldwide (mediterranean, africa, china)
x-linked inheritance (fully expressed in males, females with homozygous)
most common inherited enzyme deficiency
asymptomatic except when combined with: oxidizing chemical/drug (fava bean), severe infection, neonatal jaundice

G6PD defect

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enzyme defect of the hexose monophosphate pathway
RBCs do not make enough or it cannot function properly
necessary to reduce cellular oxidants = hemoglobin could be oxidized to methemoglobin which precipitates to form Heinz bodies (which are removed and cause bite cells & blister cells)

Lab diagnosis of G6PD

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normo, normo anemia
Bite cells, heinz body test (supravital stain)
reticulocytosis
increased unconjugated bili
hemoglobinuria/emia
screening tests for G6PD

Pyruvate Kinase (PK) deficiency general

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most common in norther european ancestry
hereditary hemolytic anemia due to enzyme defect
most common deficiency of the glycolytic pathway
inability of RBC to maintain normal ATP levels = alterations to RBC membrane
loss of K+, gain Na+ & Ca++
deformed or rigid cells that are removed by the spleen

lab diagnosis of PK

``` normo, normo anemia reticulocytosis echinocytes elevated indirect bili reduced PK ```

MAHAs

group of clinical disorders characterized by RBC fragmentation in the circulation - intravascular hemolysis fragmentation occurs as RBCs pass through fibrin deposits inside small blood vessels characterized by schistocytes, microspherocytes & increased retics

disorders associated with MAHA

Disseminated intravascular coagulation (DIC) thrombotic thrombocytopenic purpura (TTP) hemolytic uremic syndrome (HUS)

Hemolytic uremic syndrome (HUS)

multi-system disorder characterized by triad of clinical findings: 1. hemolytic anemia with RBC fragmentation 2. thrombocytopenia 3. acute nephropathy, including renal failure (clots in kidneys)

Lab diagnosis of HUS

``` normo, normo mod-severe anemia schistocytes, helmet cells, spherocytes polychromasia, occiasonal NRBC leukocytosis w/ left shift low to markedly low plts hemoglobinemia/uria increased bili, LD decreased haptoglobin ```

Thrombotic thrombocytopenic purpura (TTP)

``` syndrome of diverse issues characterized by: hemolytic anemia w/ RBC fragmentation fever thrombocytopenia ( ```

lab diagnosis of TTP

``` low hemoglobin normo, normo anemia polychromasia, NRBC SCHISTOCYTES Severe thrombocytopenia hemoglobinemia, hemoglobinuria, increased bili & LD, decreased haptoglobin ```

TTP treatment

plasma exchange with FFP | Cyrosupernantant

DIC

characterized by: widespread activation of hemostatic system secondary to: bacterial sepsis, pregnancy complications, neoplasms, trauma etc easiest way to detect is through coagulation studies

thermal injury

3rd degree burn patients may have severe acute hemolytic anemia direct effect of heat on spectrin-loss of elasticity & deformability schistocytes, spherocytes & acanthocytes

exercised induced hemoglobinuria

``` march hemoglobinuria: associated with strenuous exercise transient hemolysis usually no anemia hemoglobinuria/emia ```

Infectious agents of hemolytic anemia

malaria- most common cause of hemolytic anemia world wide bartonellosis babesiosis clostridium perfringens

general lab findings of immune mediated hemolytic anemias

normo, normo anemia spherocytes, schistocytes & polychromasia reticulocytosis POSITIVE DAT!!!!!

classification of Immune hemolytic anemias

autoimmune drug-induced alloimmune

3 subcategories of autoimmune hemolytic anemias

warm antibody AIHA cold antibody AIHA paroxysmal cold hemoglobinuria

Warm autoimmune hemolytic anemia general

most common (70% of AIHA) 2:1 female prevalence older adults & children

lab diagnosis of WAIHA

``` normo, normo anemia spherocytes retic, poly, NRBCs increased unconjugated bili POSITIVE DAT ```

cold autoimmune hemolytic anemia

``` cold agglutin disease 16-30% of AIHA chronic hemolytic anemia usually >50 yrs older peak at 70 predominance in females ```

lab diagnosis of CAIHA

``` normo. normo poly, retic, NRBC spherocytes autoagglutination of RBCs positive DAT increased unconjugated bili ```

Paroxysmal cold hemoglobinuria

rare acute form of cold generated hemolysis common in children after viral infection antibody react & induce hemolysis at lower temps massive acute hemolysis & hemoglobinuria DONATH-LANDSTEINER ANTIBODY

Donath-Landsteiner antibody

anti-P antibody binds in cold temps & causes complement activation upon warming intracellular hemolysis

lab diagnosis of PCH

``` DAT weak positive retic spherocytes & schistocytes hemoglobinuria/emia serum bili elevated ```

Drug induced hemolytic anemia

uncommon acquired cause drug itself doesn't cause RBC injury immune response to drug-induced alteration of RBC

Alloimmune hemolytic anemias

reacts to transfused cells & HDFN | Transfused: acute & delayed

Hemolytic Anemias Flashcards

(48 cards)