Wk 2 Hemolytic Anemias Flashcards
What are causes of hemolytic anemia?
- RBC destruction
- Blood loss - could even be slow leak
4 features of hemolytic anemia
- shorter RBC lifespan
- increased EPO and erythropoiesis
- Accumulated RBC content (i.e. LDH)
- Accum. Hb breakdown products (bilirubin)
What are 3 ways of categorizing hemolytic anemia?
What are 5 causes of intravascular hemolysis?
Severe injury causes RBCs to burst in circulation
1. mechanical injury to RBC
2. complement fixation
3. transfusion of incompatible RBCs
4. intracellular parasites (ie. maleria)
5. toxic injury to RBC membrane (ie. C perfringens sepsis)
What are 3 unique features of intravascular hemolysis?
- hemoglobinemia
- hemoglobinuria
- hemosiderinuria
-serum/plasma appears pink-red in blood samples w/ hemolysis
What is extravascular hemolysis?
Damaged RBC removed from circ by macrophages, esp in spleen
What are 2 causes of extravascular hemolysis?
- Appear foreign to immune system (may be tagged w/ antigen)
- are less deformable, unable to squeeze b/w endothelial cells of splenic sinusoids
3 unique features of extravascular hemolysis
- hyperbilirubinemia/jaundice due to Hb degradation in macrophages
- splenomegaly - macrophages working hard
- Pigment (bilirubin) gallstones due to excess bilirubin
2 Intrinsic vs 2 extrinsic causes of hemolytic anemia
Clinical presentation of hemolytic anemia?
Variable from asymptomatic, anemia symptoms (fatigue, dyspnea, tachycardia), hemolysis symptoms (jaundice, hematuria, hemoglobinuria)
Chronic hemolysis:
-hepatosplenomegaly
-cholestasis/cholelithiasis
Lab tests to eval for hemolysis and expected results
What is haptoglobin?
Made by liver
In blood plasma, haptoglobin binds with high affinity to free hemoglobin released from erythrocytes, and thereby inhibits its deleterious oxidative activity. Compared to Hp, hemopexin binds to free heme
What causes an increase in LDH?
Released when RBC lysed
Why is indirect/unconjugated bilirubin increased in hemolytic anemia?
B/c hemolysis releases Hgb (which breaks down into bilirubin) more quickly than the liver can conjugate the bilirubin
What is LDH?
Lactate dehydrogenase is abundant in RBCs (and others)
Hemolysis -> RBC content released -> increased LDH
*LDH not specific to hemolysis, so can be elevated in other conditions too
What is haptoglobin?
A circulating PRO that binds free Hb to prevent its excretion in urine
Haptoglobin-Hb complexes are quickly cleared by macrophages
Lots of excess free Hb = low haptoglobin
Can be decreased in intravascular or extravascular hemolysis
-in extravascular, free Hb escapes macrophages in circ and binds haptoglobin
What are 7 pertinent peripheral smear finding in hemolytic anemias?
- Heinz bodies
- Bite cells
- Spherocytes (small, no central pallor)
- elliptocytes
- schistocytes (fragmented RBCs)
- Sickled cells
- Target cells
What is a bite cell?
Specific to G6PD deficiency
-appear to have bit taken out of them
Wright stain only
What are Heinze bodies?
Precipitates of Hb after macrophages took bite out of RBC
Supravital stain only
What are elliptocytes?
oval shaped (elliptical) RBCs
-abnormality of RBC membrane cytoskeleton
What are spherocytes?
Small RBC w/ spherical shape and no central pallor
What are schistocytes?
Fragmented RBCs
What does hemoglobinuria look like?
Possible increased urine Hb if intravascular hemolysis and serum haptoglobin depleted
Hemolytic anemia diagnostic flowchart
What does the DAT (Coombs test) look for?
Tests for antibodies on RBCs
If DAT test is positive, what is tested next?
IgG (+/- C’) presence indicates warm AIHA
IgM + C’ indicates cold AIHA
What if DAT test is negative?
Determine if anemia is hereditary or acquired w/ blood smear
What are 3 thrombotic microangiopathies?
- TTP - thromotic …
- HUS - hemolytic …
- DIC -disseminated intravascular coagulation
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