What is PNH?
Paroxysmal Nocturnal Hemoglobinuria
Paroxysmal nocturnal hemoglobinuria (PNH) is a rare, acquired disease, which means it develops in some people over time. A change occurs in the body’s stem cells, located in the bone marrow, where red blood cells are produced.1-3
What is the effect of this change?
Your body will keep making cells that are missing important protective proteins.
Without these proteins, your body’s natural defense system destroys these red blood cells. It’s a process known as hemolysis.1,2

PNH is rare, but you’re not alone
For every one million people, there are about 12-13 patients with PNH each year4
Both men and women can get PNH5
PNH can occur at any age; the average age at diagnosis is in the early 30s5,6
PNH affects people of every racial and ethnic group6
Understanding hemolysis
When your body destroys unprotected red blood cells, it’s called hemolysis.2 When you have PNH, hemolysis is always happening.7-9 This is the main cause of the major health problems in PNH, including the most severe.4,7
The signs and symptoms of PNH are often similar to other diseases, which makes PNH difficult to diagnose.8,10
Most common symptoms:4,7
Testing for PNH
If you show signs of hemolysis, your doctor may request a high-sensitivity flow cytometry
Using a small sample of blood taken from your arm, this test measures the percentage of blood cells affected by PNH, also known as your clone size.11

Understanding clone size
A larger clone size means you have a higher percentage of PNH blood cells, but even small clone sizes can lead to PNH-related health problems.11 Your clone size may grow over time, so it’s important to monitor your symptoms and lab results.4
Tracking test results
To monitor your PNH, your doctor will consider all of your lab test results, signs, and symptoms, which may vary from person to person.
Everyone’s experience with the disease can be unique. No single sign, symptom, or lab result defines PNH.10,12-15
PNH-related tests
Some lab tests that your doctor may order include:4,10,16
- Lactate dehydrogenase (LDH) level, which tests the amount of LDH in the blood stream. A high amount of LDH in the blood is an indicator of acute or chronic cell damage and/or hemolysis, which is a leading indicator of PNH
- Complete blood count (CBC) measurements—red blood cells (RBCs), white blood cells (WBCs), and hemoglobin (Hb)
Connect with
your support system
People living with PNH and other rare diseases can find the support they need. Find an upcoming event in your area to meet other people who understand what you’re going through and want to share in their journey.