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 cellsStem cells are a type of cell in the body that are able to develop into many different types of cells in the body (for example, blood cells, skin cells, intestinal cells, etc). Stem cells serve as a repair system for the body.17, including in the bone marrowBone marrow is the soft tissue inside your large bones. It works to create the cells in your blood: red blood cells, white blood cells, and platelets.3, where red blood cellsRed blood cells are a type of cell found in your blood that delivers oxygen and removes waste (carbon dioxide) in your body. Red blood cells affected by PNH are attacked and destroyed because they are missing protective proteins.3,7 are produced.1-3

What is the effect of this change?

Your body will keep making cells that are missing important protective proteinsProteins are the building blocks of life. The body needs protein to repair and maintain itself. In PNH, some or all red blood cells lack important protective proteins. Without these proteins, PNH red blood cells are destroyed by the body’s natural defense system, resulting in hemolysis.4,7,17.

Without these proteins, your body’s natural defense system destroys these red blood cells. It’s a process known as hemolysisHemolysis is the destruction of red blood cells by the body’s natural defense system. Hemolysis is the main cause of the signs, symptoms, and serious health problems in PNH, including some that are life-threatening.4,7,17.1,2

Compromised red blood cells Very compromised red blood cells

PNH is rare, but you’re not alone

For every one million people, there are only 1.3 new cases of 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

Testing for PNH

High-sensitivity flow cytometry

If you show signs of hemolysis, your doctor may request a high-sensitivity flow cytometry test.4High-sensitivity flow cytometry is the gold standard test for confirming whether or not you have PNH. It counts the actual number of red and white blood cells affected by PNH in a small blood sample taken from your arm. The results indicate your clone size. Remember, even patients with small clone sizes can have PNH symptoms that may greatly limit their lives.1,7,10

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

blood cells

Understanding clone size

A larger clone sizeClone size is the percentage of blood cells in your body affected by PNH.1 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 (LDHLactate dehydrogenase (LDH) is an enzyme found in red blood cells that is released during hemolysis. Testing for LDH can help show how much hemolysis is happening in your body.10,17) 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 (CBCComplete blood count (CBC) is a lab test that measures and evaluates several components and features of your blood and detects a wide range of disorders.3) measurements—red blood cells (RBCs), white blood cells (WBCsWhite blood cells (WBCs) are a type of cell found in your blood that helps your immune system fight disease and infection.20), and hemoglobin (HgbHemoglobin (Hgb) is the oxygen-carrying, reddish-brown material found inside red blood cells. When it is released into the bloodstream during hemolysis, it becomes free hemoglobin. Free hemoglobin is harmful and can lead to serious health problems.1,17)

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