How does my doctor know I have PNH?

PNH is a rare disease. Many doctors have never seen a case of it. So people with PNH may have symptoms for several years before they get a correct diagnosis.

3 Types of Blood Cells

With PNH, your doctor can usually divide your blood cells into 3 types:

  1. PNH I cells, or Type I cells: These cells respond in a healthy way to the complement system. They are normal cells.
  2. PNH II cells, or Type II cells: These cells are partially sensitive to the complement system. They are missing some of the proteins that protect them from attack.
  3. PNH III cells, or Type III cells: These cells are extremely sensitive to the complement system. Of the 3 groups of cells, these ones break apart most easily. They are missing all the proteins that protect normal cells from attack. Most people with PNH have mostly Type I and Type III cells. But the amount of each type of cell can vary greatly.

How did my doctor classify my blood cells into these 3 groups?

Your doctor probably used a flow cytometry test. This test lets your doctor see if any proteins were missing from your red blood cells. It can also be done on certain white blood cells called granulocytes.

FLAER is a new type of flow cytometry test.

You may have heard of a test called "Ham's test" that was used in the past to check for PNH. Because this test does not give correct results, it is no longer used.

What other tests may I get?

Your doctor may ask you to get other lab tests as well. These include:

Your doctor may also look for high levels of:

  • A pigment called bilirubin
  • An enzyme called LDH (lactate dehydrogenase)
  • Young red blood cells in your bone marrow