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Paroxysmal Nocturnal Hemoglobinuria (PNH)

What Is Paroxysmal Nocturnal Hemoglobinuria?

When you have paroxysmal nocturnal hemoglobinuria (PNH), red blood cells in your body break apart before they should. It happens because the proteins that would normally protect them from your immune system are missing. Your immune system attacks the red blood cells and breaks them down.

You can get this rare blood disease at any age. You aren’t born with it. It happens over time. Although it can be life-threatening, treatments can help you feel better and, in some cases, cure it.

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PNH affects everyone differently. Some people have only minor problems, but for others, it's much more severe. The biggest concern is blood clots. About 40% of people with PNH have one at some point.

Causes

PNH comes from your genes, but you don't get it from your parents, and you can't pass it on to your kids.

A change in a gene, called a mutation, causes your bone marrow to make abnormal red blood cells. These cells don't have proteins that shield them from your immune system. So your body attacks them and breaks them down, a process doctors call hemolysis.

Some doctors believe PNH is related to weak bone marrow. People with a certain type of anemia, called aplastic anemia, are more likely to get PNH. The reverse is also true: People with PNH are more likely to get aplastic anemia, though not everyone does. In this condition, your bone marrow stops making new blood cells.

Symptoms

PNH gets its name from one of its more common symptoms. About half of people with PNH pass dark or bright red blood in their urine at night or in the morning. "Paroxysmal" means "sudden," "nocturnal" means "at night," and "hemoglobinuria" means "blood in the urine."

PNH symptoms are caused by:

  • Broken red blood cells
  • Too few red blood cells (which can cause anemia)
  • Blood clots in your veins

You could have many symptoms or just a few. Usually, the more of the faulty blood cells you have in your body, the more the condition will affect you.

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