Paroxysmal nocturnal hemoglobinuria (PNH) affects your bone marrow, where your body makes new blood cells. It can be hard to diagnose. For one thing, it's rare. And its symptoms look like those of many other diseases.

Your doctor might suspect that you have PNH if you've had blood clots or if you have a problem with your red blood cells called anemia. Symptoms of anemia include:

  • Pale skin
  • Dark-colored urine
  • Fever
  • Weakness
  • Confusion

PNH symptoms include:

  • Tiredness
  • Bruising
  • Shortness of breath
  • Severe headaches

If you've had symptoms like these and they're not from anything else, see your doctor.

Diagnosing PNH usually starts with a physical exam and a health history. Your doctor will ask you about your symptoms and your overall health. One of the questions you might get is whether you've had aplastic anemia. That's when your immune system attacks your bone marrow. Aplastic anemia can cause PNH.

Blood Tests

A few blood tests can help your doctor figure out if you have PNH.

Lactate dehydrogenase (LDH) test. You might have PNH if you have a high lactate dehydrogenase (LDH) level. This test is sometimes part of a comprehensive metabolic panel -- a blood test your doctor uses to monitor your health or screen for diseases like high blood pressure or diabetes.

LDH is an enzyme in your cells that helps them make energy. The amount of LDH in your blood goes up when something destroys cells or tissues. When it damages red blood cells, PNH raises your LDH level.

Flow cytometry. This is the most accurate way to diagnose PNH. This test uses a sample of your blood. A lab uses proteins called antibodies attached to a fluorescent dye to find other proteins called antigens on the surface of your blood cells.

The flow cytometry test measures how many of your blood cells are missing a protein called GPI. GPI protects your red blood cells from destruction and stops blood clots from forming. People with PNH don't have enough of it. That can lead to things like damaged red blood cells and blood clots.

Bone Marrow Tests

Bone marrow is the soft inner part of your bones. Your body makes new blood cells there. Bone marrow tests show whether your body makes enough healthy blood cells.

A bone marrow test won't confirm that you have PNH, but it can rule out other bone marrow problems that might cause your symptoms, like aplastic anemia or myelodysplastic syndrome.

During a bone marrow test, your doctor uses a needle to remove a small sample from inside your bone. Your bone marrow contains liquid and spongy tissue.

Bone marrow aspiration removes the liquid part of bone marrow.

Bone marrow biopsy removes a sample of tissue.

A Second Opinion?

It could take some time for you to get a diagnosis of PNH. It helps to see a doctor who has experience diagnosing and treating it. If you don't get a clear answer from the first doctor you visit, you should get a second opinion.

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