Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder that causes your red blood cells to break down before they should. This causes hemoglobinuria, or hemoglobin in your urine. Hemoglobin is a protein found in red blood cells.

With PNH, platelets are also more prone to clotting than usual. This can lead to potentially life threatening blood clots. People with PNH also have bone marrow dysfunction that can cause low blood cell levels.

Read on to learn more PNH, including the cause, outlook, and treatment.

Most cases of PNH are caused by a mutation in the PIGA gene of a bone marrow stem cell. Bone marrow stem cells develop into blood cells. If the mutated stem cell expands and multiplies, PNH develops.

The mutated stem cells develop into blood cells that lack certain proteins, which help protect blood cells from your complement system. This is a part of your immune system that breaks down bacteria, viruses, and other foreign cells. The complement system mistakes PNH blood cells for foreign cells and destroys them.

People aren’t born with the PIGA mutation that causes PNH. Instead, they acquire it later in life. The mutation occurs randomly, for no known reason.

Other conditions that affect your bone marrow may also allow the mutated stem cell to expand and multiply.

Red blood cells contain an iron-rich protein known as hemoglobin. If you have PNH and your complement system destroys red blood cells, your body gets rid of the hemoglobin through your urine.

This is known as hemoglobinuria. It can cause your urine to appear red, brown, or darker than usual.

Hemoglobinuria tends to be most noticeable in the morning because your urine becomes more concentrated during sleep. However, PNH isn’t active only at night.

To diagnose PNH, a healthcare professional will start by asking about your symptoms and medical history.

PNH symptoms vary from one person to another. Some people with PNH have episodes of red, brown, or dark-colored urine, especially in the morning. Other potential symptoms include:

  • fatigue
  • weakness
  • dizziness
  • headache
  • back pain
  • chest pain
  • abdominal pain
  • rapid heartbeat
  • skin that’s paler than usual
  • difficulty breathing, especially while exercising
  • trouble swallowing
  • esophageal spasms
  • erectile dysfunction

A variety of conditions can cause these symptoms, not just PNH. So, to learn what’s causing your symptoms, the doctor may order one or more tests.

Flow cytometry is a blood test used to diagnose PNH. It can tell a doctor about how many blood cells in your body carry the PIGA mutation.

Bone marrow transplantation is the only cure for PHN. It has a high risk of side effects, though, so a doctor will recommend this procedure only if you have severe PNH that hasn’t responded well to other treatments.

Other treatments for PNH are available to reduce symptoms and lower your risk of complications.

If you have PNH, your recommended treatment will depend on how severe the condition is. Some people with PNH have stable, mild symptoms for many years. If the condition progresses, it can cause serious symptoms that may lead to life threatening complications.

If you have few symptoms of PNH, your doctor may recommend nutritional supplements, such as folic acid and iron, to support red blood cell production.

To treat more severe PNH, your doctor will prescribe eculizumab (Soliris) or ravulizumab (Ultomiris).

These medications are monoclonal antibody complement inhibitors. They bind to complement component 5 (C5), which is an enzyme in the complement system that helps break down cells. When medication binds to C5, it stops the enzyme from breaking down blood cells.

Soliris and Ultomiris are given intravenously. If a doctor prescribes one of these medications, you will need to visit an infusion clinic to receive regularly scheduled doses. Alternatively, a nurse may visit you at home to administer the medication.

A healthcare professional may also prescribe other treatments to manage symptoms or complications of PNH.

In the past, people with PNH had reduced life expectancy due to limited treatment options. According to a 2020 research review, they lived for an average of 10 to 22 years after developing the condition.

But with improved treatments, survival rates have since improved. The average lifespan for people with PNH is now near standard life expectancy levels. With treatment, it’s possible to lead a long and fulfilling life with PNH.

In rare cases, PNH blood cells disappear and symptoms of the condition resolve on their own, according to researchers in a 2021 article. This is known as spontaneous remission. The researchers don’t know why it happens.

Bone marrow transplantation can also cause PNH to resolve. However, doctors prescribe this treatment only when PNH is very severe and other treatments haven’t worked well.

Most cases of PNH require ongoing treatment to manage.

Aplastic anemia is a known risk factor for PNH.

Aplastic anemia is a very rare blood disorder in which your bone marrow doesn’t produce enough blood cells. In most cases, it’s an autoimmune condition that develops when your immune system attacks your bone marrow.

There are other types of anemia, such as iron deficiency anemia and sickle cell anemia. These are much more common types of anemia and they do not raise your risk of PNH.

PNH can cause low levels of white blood cells, which play important roles in your immune system. As a result, PNH may weaken your immune system and raise your risk of infections.

PNH is also linked to increased risk of leukemia. This type of cancer affects blood-forming tissues, including bone marrow. If you develop leukemia, it will reduce your immune system’s ability to fight off infections.

Certain treatments for PNH may also affect your immune system.

These include eculizumab and ravulizumab, which raise your risk of meningococcal disease. This is a bacterial infection that can cause meningitis. If you take eculizumab or ravulizumab, your doctor will likely encourage you to get the meningitis vaccine and may prescribe preventive antibiotics.

If you receive a bone marrow transplantation to treat PNH, your doctor will prescribe chemotherapy, radiation, or both to suppress your immune system. This will stop your immune system from destroying the donor bone marrow. However, it also raises your risk of infection.

Your doctor may also prescribe immunosuppressive medication if you have bone marrow failure caused by PNH or aplastic anemia. This type of medication raises your risk of infection.

Talk with your doctor to learn how you can lower your chances of developing infections while living with PNH.

PNH is a rare blood disorder that raises your risk of blood clots, infections, and leukemia.

If you have PNH, getting treatment can help reduce your symptoms, lower your risk of serious complications, and improve your long-term outlook.

To treat PNH, your doctor may prescribe nutritional supplements, medication, or a combination of both. If you have severe PNH that hasn’t responded well to other treatments, they may recommend a bone marrow transplantation.