Paroxysmal Nocturnal Hemoglobinuria (PNH): What You Need to Know

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare blood disorder. You may never have heard of it before your diagnosis. So what is PNH, and how does it affect your body? Knowing the basics can help you feel more in control.¹

What PNH is and who is at risk

“Paroxysmal” means sudden. “Nocturnal” means at night. “Hemoglobinuria” means hemoglobin in your urine. Together, these terms make up PNH, which is named for when a person notices red, brown, or dark-colored urine when using the bathroom late at night or early in the morning.¹

Not everyone with PNH has dark urine, though. Most people first see a doctor because of extreme tiredness.¹

Only about 1 in 1 million people are diagnosed with PNH each year. PNH is most common in adults in their 30s and 40s, but it can happen at any age. People with certain bone marrow conditions, like aplastic anemia, have a higher risk.¹

What causes PNH?

PNH is acquired. This means it develops during your lifetime. It starts with a change (mutation) in a gene called PIGA. The change happens in bone marrow stem cells that make blood cells. PNH is not passed down from parents to children.^1,2

In healthy blood, the PIGA gene creates protective surface proteins that act as a shield to keep red blood cells safe from the immune system. In PNH, red blood cells do not have this protective shield. As a result, they are open to attack by the complement system. The complement system is a chain of immune reactions that can damage and destroy cells. This cell destruction is called hemolysis.^1,3,4

Common symptoms of PNH

Symptoms can be mild or severe. They may flare after an infection or other trigger. PNH can cause:^1-4

• Extreme tiredness (fatigue) – This is the most common symptom.
• Dark urine – Urine may look dark, often in the morning. Hemoglobin from broken red blood cells causes this.
• Shortness of breath – Too few healthy red blood cells (anemia) can cause this.
• Pain – You may have belly, back, or chest pain. Hemolysis can trigger painful muscle spasms.
• Trouble swallowing – Spasms in your food pipe (esophagus) can make swallowing hard.
• Kidney problems – PNH can strain your kidneys.
• Erectile dysfunction – Some men with PNH have trouble getting or keeping an erection.

Why PNH can be hard to diagnose

Because symptoms vary so much, diagnosis is often delayed. Many people never have the classic dark urine. One study of more than 4,000 people with PNH showed that only about 45 percent had a history of dark urine, while 81 percent had fatigue.^3,4

If your symptoms were brushed off for a while, you are not alone. What you felt was real, and it matters.

Blood clots: a serious complication of PNH

Blood clots (thrombosis) are the most serious complication of PNH. In untreated PNH, they are the leading cause of death. PNH clots often form in unusual places. These include veins in the liver, belly, or brain.^1,3

Ask your care team which signs of a blood clot to watch for, and know when to get emergency care.

How PNH is treated

Most people with PNH take a type of drug called a complement inhibitor. These drugs keep the complement system from destroying red blood cells. They can be IV infusions, shots under the skin, or pills. Some people may also need blood transfusions or blood thinners.^1,3

The first complement inhibitor made a big difference in PNH care. Blood clots fell by 92 percent compared with earlier years. Regular checkups also help your care team spot problems early.³

Complement inhibitors raise the risk of certain serious infections. You will need specific vaccines before you start.³

A stem cell transplant is the only cure for PNH. But it carries serious risks, and finding a compatible donor is not always possible.^1,3

Living with a PNH diagnosis

A rare disease diagnosis can bring many feelings. You may feel scared or overwhelmed. You may even feel relieved to finally have an answer. All of these feelings are normal.

People with chronic illness have a higher risk of depression. Depression is treatable, even with a long-term condition. Tell your doctor if you often feel sad or hopeless.⁵

PNH is lifelong, but it can be managed. Complement inhibitors help most people with PNH manage it. Before these drugs, many people lived only 10 to 20 years after diagnosis. Today, people who take them can expect a near-normal lifespan.^1,4

Talking charge of your PNH care

You can take an active role in your care. Ways to start include:¹

• Track your symptoms – A simple log helps you spot and share changes.
• Tell every provider you have PNH – Include doctors you see for other needs.
• Stay connected to your hematologist – Know how to reach your blood specialist.
• Find your community – Others with rare diseases can help you feel less alone.

Your hematologist can explain what your results mean for you. Reach out about any new or changing symptoms. You do not have to figure this out on your own.