This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
The gold standard lab test for diagnosis of paroxysmal nocturnal Hemoglobinuria is 
Select and explain. 
A. Ham test, B. Nestroft test, C. Sucrose lysis test, D. Flow cytometry
D: Flow cytometry
Answer: D: Flow cytometry 
Explanation: Flow cytometry

It is gold standard test for diagnosis of PNW
It shows absence of CD55 and CD59 on RBC