Glossary of terms pertaining to your disease and management

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Acquired: Not inherited or present at birth, but developing after birth.¹⁷
Anemia: The condition of having a lower-than-normal number of red blood cells or quantity of hemoglobin. Anemia diminishes the capacity of the blood to carry oxygen.³
Aplastic anemia (AA): Anemia that results from the failure of the bone marrow to produce enough blood cells.¹⁷
Arteries: Blood vessels that carry blood from the heart to the rest of the body.¹⁷
Blood clot (thrombosis): Blood clots form when parts of your body’s blood clump together. In a healthy body, this can stop bleeding when you’re cut or injured. But in certain conditions, these clumps can block blood flow in the veins and arteries, which can be dangerous. In PNH, a clot can happen at any time and can cause serious health problems.^3,16
Blood test: A test done to look at parts of the blood. Examples of tests include complete blood count (CBC), lactate dehydrogenase (LDH), and high-sensitivity flow cytometry. Results from these blood tests provide information about your PNH.^3,4,10,16
Bone marrow: 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
Chronic kidney disease (CKD): The gradual loss of kidney function over a period of months or years. Your kidneys have the important job of filtering your blood. When they don’t work correctly, waste builds up in your blood and can make you sick.³
Clone size: The percentage of blood cells in your body affected by PNH.¹
Complement: Also known as the Complement Cascade; in healthy individuals, a sequence of protein reactions in the blood that is part of the body’s natural defense system. It helps fight against bacteria and other foreign matter in the body.^1,18
Complete blood count (CBC): A lab test that measures and evaluates several components and features of your blood and detects a wide range of disorders.³
Enzyme: A type of protein that helps reactions or processes happen in the body.¹⁷
Erectile dysfunction (ED): A condition found in men that affects their ability to achieve an erection.¹⁷
Fatigue: Tiredness, trouble concentrating, dizziness, and weakness to the point where even normal, everyday activities become a struggle. In PNH, fatigue is often out of proportion to the amount of anemia, as measured by hemoglobin, because it is affected by hemolysis.^4,7,17
Heart attack: Damage to an area of the heart muscle that is deprived of oxygen, usually due to a blood clot in the coronary artery. Heart attacks are serious and can be fatal.¹⁷
Hemoglobin (Hb): 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
Hemoglobinuria: Hemoglobin in the urine. About 50% of patients with PNH have it at diagnosis, but most will experience it at some time. Because of the reddish-brown color of hemoglobin, it results in dark, sometimes “cola-colored” urine.^17,19
Hemolysis: 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
High-sensitivity flow cytometry (HSFC): 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.^1,7,10
Lactate dehydrogenase (LDH): 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
Myelodysplastic syndromes (MDS): A condition in which there’s a problem with the way bone marrow makes blood cells. A small percent of PNH patients also have MDS.^10,17
Paroxysmal nocturnal hemoglobinuria (PNH): A disease where red blood cells are created without protective proteins. This causes them to burst (a process called hemolysis) and can result in serious health problems. Signs and symptoms include stomach pain, difficulty swallowing, anemia, shortness of breath, and fatigue. Life-threatening complications from PNH include blood clots, kidney failure, and damage to organs.^2,5,13,14,17
Progressive: A progressive disease is one that gets worse over time.¹⁷
Protein: Proteins 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
Pulmonary hypertension: High blood pressure in the arteries that deliver blood to the lungs. This means that blood has a hard time getting to the lungs, causing your heart to pump harder.³
Red blood cells (RBCs): 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.^7,20
Stem cells: A type of cell in the body that is 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
Stroke: Rapid loss of brain function due to a lack of blood supply to the brain, as a result of a blood clot or ruptured artery in the brain. Strokes can be life-threatening.¹⁷
White blood cells (WBCs): A type of cell found in your blood that helps your immune system fight disease and infection.²⁰