Paroxysmal nocturnal hemoglobinuria (PNH) is a rare disease that causes hemolysis — destruction of your red blood cells. Although PNH symptoms are often ongoing, certain factors can trigger hemolysis, making your condition worse for a short period of time.

It’s important to learn about what triggers PNH. You may be able to avoid many of these factors, which can help you spend less time being sick and improve your quality of life.

Why Do Hemolytic Episodes Occur?

Periods of increased symptoms — sometimes called hemolytic episodes — are often caused by your complement system (a part of your immune system that helps fight infection). When your complement system is activated or boosted, it attacks more of your red blood cells, causing you to feel sicker.

Your complement system doesn’t kill all of your red blood cells. It only destroys abnormal cells that lack certain proteins on their surface. These defective red blood cells are created by hematopoietic stem cells (HSCs) in your bone marrow — the fatty tissue found inside certain bones. When HSCs develop mutations in the PIGA gene, they produce abnormal red blood cells that don’t have any protection against the complement system.

Hemolysis gets worse when the complement system becomes more active than usual, such as during periods of stress, trauma, or when the body is fighting infection. When a hemolytic episode happens, it can lead to periods of increased symptoms, including:

• Dark urine
• Abdominal pain
• Dyspnea (shortness of breath)
• Dysphagia (swallowing problems)
• Erectile dysfunction

Potential PNH Triggers

The following factors don’t cause new cases of PNH to develop, but they may trigger worse symptoms for people who’ve already been diagnosed.

1. Mental Stress

When you’re feeling pressure, your PNH may worsen. Ongoing stress or feelings of worry may cause additional symptoms.

Research shows that your brain can communicate with your immune system, tying your emotions and thought processes to your body’s ability to protect itself from disease. When you are stressed, your brain sends signals to boost the activity of the immune system, leading to more inflammation and a more powerful complement system.

Subtle symptoms can provide clues that your stress levels are too high. In addition to increased PNH symptoms, watch out for:

• Headaches
• Upset stomach
• Muscle clenching
• Changes in appetite
• Increased smoking or drinking
• Feelings of restlessness
• Difficulty concentrating

If stress is contributing to your PNH, try to identify what’s worrying you. Take a break from these stressors if you can. Additionally, you can keep your stress levels low by adding certain habits to your daily routine, including yoga, meditation, physical activity, participating in hobbies, or socializing with loved ones.

2. Heavy Exercise

Factors that place physical stress on your body, including physical activity, may also trigger PNH symptoms.

Some research shows that your complement system becomes a little more active after a workout. Usually, this response is short-lived, and your system returns to normal within a few hours. If you exercise very strenuously, however, your complement system could be activated for up to three days afterward. This longer period of activation may occur because intense exercise damages your muscles, and your complement system helps respond to damage within your body.

Although studies haven’t directly looked at the impact of exercise on PNH symptoms, some health experts note that strenuous physical activity can contribute to PNH symptoms. Heavy weight lifting and cardiovascular exercise that gets your heart pumping very fast may trigger PNH symptoms.

However, there’s a twist. Although a single bout of heavy exercise may make this rare disorder worse — especially if you’re not used to working out — regular physical activity may improve your PNH overall. Studies have found that people who are more physically fit or have more muscle tend to have less activation of their complement system. This finding means that getting regular exercise — without pushing yourself too hard — may help your PNH.

3. Infections

If you become sick with an infection, you may experience a hemolytic episode.

Fighting infections is one of the main jobs of your complement system. When germs such as bacteria or viruses enter your body, antibodies (immune system proteins) recognize them and send signals to turn on your complement system to fight the invaders. Activated complement proteins may be more likely to target your red blood cells.

Because PNH sometimes leads to low levels of white blood cells (immune cells), you may have an increased chance of developing an infection. However, you can reduce your risk by:

• Washing your hands often, especially before making food or after using the bathroom, blowing your nose, sneezing, or petting an animal
• Staying away from others who are sick
• Not sharing drinks, utensils, or napkins with others
• Making sure any injuries, including small cuts, are washed and covered with a bandage
• Avoiding popping pimples or picking at your skin

Talk to your doctor if you develop an infection. Prompt treatment may help calm your complement system and get rid of the infection quickly.

4. Trauma

Physical trauma (serious injury) can trigger hemolysis in some cases of PNH. This may include a broken bone, concussion, or deep cut.

Part of your complement system’s job is to start processes that help your body heal after an injury. It also helps remove cells or tissues that have become too damaged to function properly. When trauma occurs, complement proteins become activated, which can enable them to also destroy your red blood cells.

Trauma typically occurs as a result of an accident. You can’t prevent accidents from happening, but here are some ways to reduce your risk:

• Be careful when cooking with hot liquids or oils.
• Keep heavy items on lower shelves within your home.
• Don’t attempt big jobs around the home if you don’t have experience — hire a professional.
• Stay alert and minimize distractions while you’re driving.
• Keep a first aid kit nearby, and seek medical attention if you experience a more serious injury.

5. Surgery

Undergoing surgery may affect your complement system and cause your red cells to start breaking apart. Surgical procedures can place physical stress on your body and lead to trauma. If your body is experiencing trauma, it causes damage to your tissues, causing your body to turn on the complement system.

In addition to causing hemolysis, surgery can increase your risk of developing potentially life-threatening thrombosis (blood clots) if you’re living with PNH. You could also develop serious bleeding problems. Both of these issues occur due to problems with platelets, the cell fragments that help your blood clot.

You can’t always avoid surgery, but your health care team may be able to give you treatments that prevent health problems during an operation. For example, you may need a platelet transfusion, in which a doctor delivers extra platelets from a donor into your veins. You may also need to take an anticoagulant (blood thinner medication) after your surgery is complete.

6. Pregnancy

Pregnancy can lead to multiple problems for people with PNH. You may be more likely to miscarry. Additionally, your baby has a 2 in 3 chance of being born prematurely or having health conditions.

During pregnancy, PNH can also increase your risk of:

• Hemolytic anemia (low levels of red blood cells due to destruction of these cells)
• Low numbers of healthy white blood cells or platelets
• Blood clots
• Preeclampsia (a condition that leads to very high blood pressure levels)

If you are considering pregnancy, talk to a hematologist who specializes in PNH and meet with an obstetrician who has experience with high-risk pregnancies. Treatments such as anticoagulants can help prevent certain PNH-related problems. You may also need increased numbers of blood transfusions (infusions of blood cells from a donor) while pregnant. Additionally, increasing your dose of a PNH medication like eculizumab (Soliris) may help you avoid hemolysis during pregnancy.

The Bottom Line

If you’re living with PNH, learn about the triggers that can make your symptoms worse and try to minimize the risks. You may need to avoid certain medications or be cautious when undergoing medical procedures or treatments that increase the risk of symptoms worsening.

Additionally, try to maintain your overall health and well-being. You may want to consider regular exercise, a balanced diet, and stress-management techniques, all of which can reduce the severity and frequency of PNH symptoms. Monitor your symptoms regularly and talk with your health care provider about any changes or concerns.

Talk With Others Who Understand

On myPNHteam, the social network for people with paroxysmal nocturnal hemoglobinuria and their loved ones, members come together to ask questions, give advice, and share their stories with others who understand life with PNH.

What’s most likely to trigger your PNH symptoms? Share your experience in the comments below, or start a conversation by posting on your Activities page.