Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder that causes your red blood cells to break down before they should.

Having PNH causes hemoglobinuria. This means your urine contains hemoglobin, which is a protein found in red blood cells.

Read on to learn about PNH, including the cause, outlook, and what to expect when living with this disease.

PNH falls into the category of autoimmune hemolytic anemia (AIHA), which is a rare set of disorders where the immune system erroneously targets and destroys healthy 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.

In most cases, the disease is 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.

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

People are not 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 darker than usual.

Hemoglobinuria tends to be most noticeable in the morning because your urine becomes more concentrated during sleep. This explains the “nocturnal” in paroxysmal nocturnal hemoglobinuria. However, PNH is not active only at night.

Bone marrow transplantation is the only cure for PHN, but it carries a high risk of side effects.

A doctor will recommend this procedure only if you have severe PNH that has not responded well to other treatments.

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

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 do not 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 have not worked well.

For most PNH cases, ongoing treatment is necessary to manage the condition.

Aplastic anemia is a known risk factor for PNH.

Aplastic anemia is a rare blood disorder in which your bone marrow does not 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, like iron deficiency anemia and sickle cell anemia. These are much more common types of anemia, and they do not raise your risk of PNH.

Researchers believe PNH may be related to autoimmune bone marrow failure.

While it’s not cancer, it can, in rare instances, progress to leukemia, which reduces the immune system’s ability to fight off infections.

Research suggests this occurs in about 2-6% of cases.

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 and other conditions.

Higher risk of bacterial infections

Certain PNH treatments may also affect your immune system.

These include eculizumab (Soliris) and ravulizumab (Ultomiris), which raise your chance of developing 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 they may prescribe preventive antibiotics.

Treatments that suppress the immune system

If you undergo 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. It’s important to note that this procedure also raises your risk of infection.

Your doctor may prescribe immunosuppressive medication if PNH or aplastic anemia causes bone marrow failure. 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.

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

But with improved treatments, survival rates have since improved. The average lifespan for people with PNH is now near the life expectancy of someone who does not have the condition. With treatment, people diagnosed with PNH can lead a long and fulfilling life.

It can be challenging to live with PNH. For one, fewer than 40% of people get diagnosed with PNH within a year of symptoms beginning. In a quarter of cases, it takes five years to get a diagnosis.

Having symptoms and not getting the right diagnosis for a long time can be distressing. Then, once you have the diagnosis, you must learn how to manage the disease and deal with potential complications.

These may be mild, like fatigue, or more serious, like blood clots or organ failure. Having anemia and needing regular transfusions can also take a toll on your life by forcing you to travel to infusion centers.

All of this can affect your work and family life in significant ways. That said, there are resources that can help.

For example, the Aplastic Anemia & MDS International Foundation (AA MDS) supports people affected by bone marrow failure diseases, such as PNH.

Additionally, you may be able to get financial assistance for treatment through The National Organization for Rare Disorders’ Paroxysmal Nocturnal Hemoglobinuria (PNH) Patient Assistance Program

What are the signs and symptoms of PNH?

The main symptoms of PNH are darker urine, blood clots, anemia, fatigue, difficulty breathing and swallowing, abdominal pain, and throat spasms. These symptoms can range from mild to severe and sometimes life threatening.

How is PNH diagnosed?

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, dizziness, pain, difficulty breathing, and more.

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

What treatments can help with PNH?

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.

Treatments include anticoagulants, supplements, and medications called monoclonal antibody complement inhibitors. People who don’t respond to these treatments will need a bone marrow transplant. However, this procedure comes with potential complications

Learn more: What you need to know about paroxysmal nocturnal hemoglobinuria

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 has not responded well to other treatments, they may recommend bone marrow transplantation.