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How is PNH diagnosed?

PNH is a disease of hemolysis, which is the medical way of saying "destruction of red blood cells." PNH is a complex disease that often is mistaken for other diseases. It can be difficult to detect and sometimes takes years to diagnose. Rather than focusing on one main complaint, a diagnosis needs to take into consideration all the signs, symptoms, and laboratory tests that may point to PNH.

The signs and symptoms of PNH can vary widely from patient to patient.² Common symptoms associated with PNH include stomach pain, difficulty swallowing, anemia, shortness of breath, and tiredness (fatigue). More serious complications include blood clots, chronic kidney disease, and pulmonary hypertension.

To find out if you have PNH, your doctor will perform a complete clinical assessment, which may include several blood tests (such as your LDH level), the symptoms you’re experiencing, and laboratory tests such as high-sensitivity flow cytometry.

LDH (lactate dehydrogenase) is an enzyme that is found in many organs in your body, and is especially common in your red blood cells. If you have high levels of LDH, it may mean that excessive hemolysis (destruction of red blood cells) is occurring.¹ Excessive and continual hemolysis is the main cause of the signs and symptoms and major health problems in PNH.¹

My doctor just informed me that he wants to monitor my LDH levels. Why is LDH important?

LDH (lactate dehydrogenase) is an enzyme that is found in many organs in your body, and is especially common in your red blood cells. If you have high levels of LDH, it may mean that excessive hemolysis (destruction of red blood cells) is occurring.¹ Excessive and continual hemolysis is the main cause of the signs and symptoms and major health problems in PNH.¹

By measuring your LDH, your physician can determine the degree of hemolysis (destruction of red blood cells) in your body.¹ Knowing your beginning LDH and monitoring it over time will help you and your doctor keep better track of the progression of your PNH. It can also be used to help assess the risk for developing serious complications associated with PNH.

What is flow cytometry?

High-sensitivity flow cytometry is the standard diagnostic test for confirming a PNH diagnosis and in most cases has replaced the need for older tests including the Ham test or sucrose hemolysis test.^3,4 This test involves a sophisticated laboratory technique used to identify and sort blood cells and their components.

By using flow cytometry, a process in which a single line of cells is placed in a fluid stream that is then passed through a beam of laser light, physicians can determine the amount of PNH cells in your blood.^3,5 Flow cytometry identifies PNH red blood cells by finding those cells that are missing a protective protein on their surface. This helps to determine PNH clone size in the blood sample — the total percentage of cells that are missing these protective proteins.

What are some of the signs and symptoms a doctor may use to help diagnose PNH?

The signs and symptoms of PNH can vary widely from patient to patient.² Chronic hemolysis (destruction of red blood cells) is the main cause of the signs, symptoms, and major health problems of PNH.¹ Common signs and symptoms associated with PNH include stomach pain, difficulty swallowing, anemia, shortness of breath, and tiredness (fatigue). More serious complications include blood clots, chronic kidney disease, and pulmonary hypertension.

Being aware of your symptoms, as well as your lab values, can provide a more complete picture of your PNH. There are many lab values that can be helpful in measuring your PNH. One of the most important lab values is called LDH (lactate dehydrogenase). By measuring your LDH, your physician can determine the degree of hemolysis in your body.¹ Knowing your beginning LDH and monitoring it over time will help you and your doctor keep better track of the progression of your PNH. It can also be used to help assess the risk for developing serious complications associated with PNH.

If you have any signs or symptoms you think may be related to PNH, talk to your doctor about what steps you can take. Speaking to a physician who specializes in PNH can be helpful. If your doctor is not a specialist, he or she may refer you to someone who is.

Why is PNH hard to diagnose?

PNH can be difficult to detect because it is a complicated disease in which the signs and symptoms are nonspecific, unpredictable, and often similar to those of other diseases. PNH affects different people in different ways.² In fact, many people with PNH are also diagnosed with bone marrow disorders such as aplastic anemia or myelodysplastic syndromes, which may further complicate the diagnosis and treatment of PNH. Another complicating factor is that PNH is rare and doctors do not always think to test for it.

Why is early diagnosis of PNH important?

PNH is a progressive disease, which means that it can get worse over time. With an early diagnosis, you and your healthcare team can better manage your PNH by taking action to improve the signs and symptoms of PNH, and reduce the risk of serious health problems associated with the disease. Common signs and symptoms associated with PNH include stomach pain, difficulty swallowing, anemia, shortness of breath, and tiredness (fatigue). More serious complications include blood clots, chronic kidney disease, and pulmonary hypertension, all of which can be life threatening.^1,6,7

Now there is an effective treatment available that can help reduce hemolysis in people with PNH. This alone is reason enough to suggest that those whose signs and symptoms indicate they may have PNH be tested for PNH.

I was originally diagnosed with aplastic anemia and now have been advised that I should be tested for PNH each year. Why is that?

People who have been diagnosed with bone marrow disorders like aplastic anemia (AA) or myelodysplastic syndromes (MDS) should be tested to see if they have PNH because approximately 70% of people with AA and as many as 42% of patients with MDS have some PNH cells.^8,9 If you have AA, you should be tested for PNH at diagnosis and annually; for people with MDS, it’s important to be tested at diagnosis. These testing guidelines are recommended because PNH can get worse unexpectedly, even if you are being treated for AA or MDS.

Both AA and MDS can cause fewer red blood cells to be produced. In PNH, some or all red blood cells are constantly being destroyed. The destructive nature of PNH can have a significant impact on patients with AA or MDS, especially for those whose red blood cell count is very low.⁴ If you have AA or MDS you may want to be tested for PNH in order to avoid further complications. Should you test positive for PNH, your doctor may consider additional or alternative treatment options for your AA or MDS.