Hemolysis – Quiz

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A 24-year-old man presents with jaundice and dark urine after a viral illness. Labs: Hb 8.5 g/dL, LDH ↑, indirect bilirubin ↑, haptoglobin undetectable. DAT is strongly positive. What is the most likely diagnosis?

a
Hereditary spherocytosis
b
Warm autoimmune hemolytic anemia
Positive DAT indicates immune-mediated hemolysis, most consistent with warm AIHA.
c
Paroxysmal nocturnal hemoglobinuria
d
Vitamin B12 deficiency

Which of the following markers is most specific for intravascular hemolysis?

a
Elevated indirect bilirubin
b
Reticulocytosis
c
Hemoglobinuria
Hemoglobinuria (Hb in urine) occurs only when free hemoglobin escapes into plasma and is filtered by kidneys, specific for intravascular destruction.
d
Low haptoglobin

Which condition can mimic hemolysis by causing elevated LDH and indirect bilirubin without true RBC destruction?

a
Glucose-6-phosphate dehydrogenase deficiency
b
Vitamin B12 deficiency
B12 deficiency causes intramedullary destruction of precursors (“ineffective erythropoiesis”), raising LDH/bilirubin but not due to peripheral RBC hemolysis.
c
Thrombotic thrombocytopenic purpura
d
Malaria

42-year-old man with recurrent morning dark urine is found to have pancytopenia and intravascular hemolysis. Flow cytometry shows absent CD55/CD59 on RBCs. Which treatment specifically targets the underlying mechanism?

a
Rituximab
b
Hydroxyurea
c
Eculizumab
Eculizumab inhibits complement C5, preventing complement-mediated RBC lysis in PNH.
d
Prednisone

In glucose-6-phosphate dehydrogenase (G6PD) deficiency, which of the following is the key mechanism of RBC destruction?

a
Complement-mediated lysis
b
Oxidative damage due to impaired NADPH generation
Without G6PD, RBCs can’t regenerate reduced glutathione, making them vulnerable to oxidant stress → hemolysis.
c
Direct immune attack on RBCs
d
Fragmentation in microangiopathy

Match the laboratory finding with the mechanism of hemolysis

Indirect hyperbilirubinemia
Hemoglobinuria
Low haptoglobin
Hemoglobin bound and cleared by scavenger protein
Free hemoglobin filtered through kidneys
Macrophage processing of heme
Correct! Sorry, Incorrect.

Match the disease with the predominant type of hemolysis

Hereditary spherocytosis (HS)
Thrombotic thrombocytopenic purpura (TTP)
Paroxysmal nocturnal hemoglobinuria (PNH)
Extravascular hemolysis
Intravascular hemolysis
Intravascular from mechanical shearing
Correct! Sorry, Incorrect.

Match the clinical mimic with the lab abnormality it can share with hemolysis

Cirrhosis
Vitamin B12 deficiency
Large hematoma resorption
Indirect hyperbilirubinemia
High LDH
Both bilirubin and LDH elevations during breakdown of pooled blood
Correct! Sorry, Incorrect.

Match the test with its utility in hemolysis evaluation

Flow cytometry for CD55/CD59
Eosin-5-maleimide (EMA) binding test
DAT (Direct antiglobulin test)
Detects immune-mediated RBC destruction
Confirms hereditary spherocytosis
Identifies paroxysmal nocturnal hemoglobinuria
Correct! Sorry, Incorrect.

Place the conditions under Intravascular Hemolysis or Extravascular Hemolysis

G6PD deficiency (oxidant stress–induced)
Thrombotic thrombocytopenic purpura (TTP)
Mechanical prosthetic heart valve
Paroxysmal nocturnal hemoglobinuria (PNH)
Hereditary spherocytosis (HS)
Autoimmune hemolytic anemia (warm type)
Intravascular
Extravascular

Drag markers into whether they are direct indicators of hemolysis or secondary/indirect consequences

Splenomegaly
LDH ↑
Reticulocytosis
Low haptoglobin
Indirect bilirubin ↑
Hemoglobinuria
Direct indicators
Secondary consequences

Decide which diagnoses represent true RBC destruction vs mimics with similar labs

Cirrhosis
Hematoma resorption
TTP
PNH
B12 deficiency
Warm AIHA
True hemolysis
Mimics
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