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NBME 20 Answers

nbme20/Block 3/Question#10

A 59-year-old man develops fatigue and decreased ...


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submitted by divya(29),

FA 2019 Pg 415

Prosthetic heart valves and aortic stenosis may cause hemolytic anemia secondary to mechanical destruction of RBCs.

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submitted by lilyo(18),

Prosthetic valves are one of the causes of extravascular hemolysis so suspect this in a patient that has symptoms of anemia such as fatigue, pallor, jaundice. Further supporting evidence in this patient is the increased indirect bilirubin. Also, look for elevated LDH, decreased haptoglobin.

nephroguy  All of this is correct except its intravascular hemolysis, not extravascular. Also look for hemosiderinuria, hemoglobinuria and schistocytes on blood smear +1  
dermgirl  Is not intravascular hemolysis, it is extrinsic hemolysis, specifically macroangiopathic hemolytic anemia. FA 2020 page 423. +  
vishnu_c_singh  This is actually BOTH intravascular hemolysis & extrinsic hemolysis. Extrinsic = hemolysis that isn't caused by an internal defect of the RBCs, like an enzyme/membrane defect (in other words, it's hemolysis due to an external factor like a mechanical valve). Intravascular = hemolysis that occurs within the blood vessels (RBCs get damaged as they pass through the valve). This is in contrast to extravascular hemolysis which describes hemolysis that occurs outside of the blood vessels (e.g. inside the spleen) +  

this dude had a complication aortic valve replacement which he now presents with a decrescendo diastolic murmur at the left sternal border (Aortic Regurg). The RBCs seem to get sheared as they pass thru the faulty opening of the replaced valve causing intravascular hemolysis

When conjugated bilirubin (CB) is less dan, 30% of total bilirubin----> increased the production of unconjugated bilirubin or decreased uptake. Hemolysis is the possible answer choice.

CB is 30%-50% mix-hyperbilirubinemia (Ex. Hepatitis or Alcholol) CB is more than 50% --> Obstruction (intra or extrahepatic)