Question 1

What is paroxysmal nocturnal hemoglobinuria (PNH)?

Accepted Answer

PNH is a rare, acquired blood disorder in which red blood cells lack protective surface proteins (e.g. CD55, CD59) due to a mutation, leading to complement-mediated hemolysis, anemia, thrombosis, and bone marrow dysfunction.
Source: StatPearls – Paroxysmal Nocturnal Hemoglobinuria (2023)

Question 2

What causes paroxysmal nocturnal hemoglobinuria?

Accepted Answer

PNH is caused by a mutation in the PIGA gene within bone marrow stem cells. This mutation leads to the absence of protective proteins on blood cells, making them vulnerable to destruction by the body’s immune system.

Question 3

How is paroxysmal nocturnal hemoglobinuria diagnosed?

Accepted Answer

PNH is diagnosed using flow cytometry, a test that detects the absence of protective proteins (CD55 and CD59) on red and white blood cells. Blood tests may also show signs of hemolysis, such as elevated LDH or low haptoglobin.

Question 4

What are the symptoms of paroxysmal nocturnal hemoglobinuria?

Accepted Answer

Symptoms include fatigue, dark-colored urine (especially in the morning), abdominal pain, difficulty swallowing, shortness of breath, and increased risk of blood clots. Some patients also develop low blood counts (pancytopenia).

Question 5

Why is PNH called “paroxysmal nocturnal hemoglobinuria”?

Accepted Answer

The name reflects hallmark features: paroxysmal (sudden episodes), nocturnal (most noticeable on waking), and hemoglobinuria (dark urine due to hemolysis during sleep).
Source: Wikipedia – Terminology & Presentation (2024)

Question 6

How does PNH cause pancytopenia?

Accepted Answer

PNH often coexists with bone marrow failure syndromes like aplastic anemia. This results in a reduced production of red cells, white cells, and platelets - a condition called pancytopenia.

Question 7

Why does PNH cause thrombosis (blood clots)?

Accepted Answer

PNH significantly increases the risk of blood clots due to abnormal platelet activity, chronic hemolysis, and inflammation. Thrombosis in unusual locations (like abdominal veins) is a hallmark complication.

Question 8

Why is PNH considered Coombs-negative hemolytic anemia?

Accepted Answer

Unlike autoimmune hemolytic anemia, PNH does not involve antibodies attacking red blood cells, so the Coombs test is negative. The hemolysis is due to a lack of protective surface proteins.

Question 9

Who treats paroxysmal nocturnal hemoglobinuria?

Accepted Answer

PNH is typically managed by hematologists, especially those who specialize in bone marrow failure syndromes or rare blood disorders. Treatment may involve supportive care or targeted therapies like eculizumab or ravulizumab.

Question 10

Can PNH lead to other blood cancers or complications?

Accepted Answer

While rare, some patients with PNH may develop related conditions like myelodysplastic syndromes (MDS) or acute leukemia. Close monitoring is essential to manage progression or complications.

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