What is PNH?

PNH (paroxysmal nocturnal hemoglobinuria hemoglobinuria: (hee-muh-gloe-buh-NYOOR-ee-uh) The presence of hemoglobin in the urine. ) is a very rare blood disease that causes red blood cells to break apart. PNH occurs because of a genetic change to some of your blood-forming stem cells stem cells: Cells in the body that develop into other cells. There are two main sources of stem cells. Embryonic stem cells come from human embryos and are used in medical research. Adult stem cells in the body repair and maintain the organ or tissue in which they are found. Blood-forming (hemapoietic) stem… . These defective stem cells become PNH blood cells that are missing an important coating (protein) that protects them from your immune system. If you have PNH, there will be times when your immune system destroys many red blood cells very quickly, causing low red blood cell red blood cell: The most numerous type of blood cell in healthy people. Red blood cells contain hemoglobin, a protein that picks up oxygen in the lungs and brings it to cells in all parts of the body. Also called erythrocyte, RBC. counts, as well as blood clots, muscle spasms and dark urine. This destruction of blood cells is called hemolysis hemolysis: (hi-MOL-uh-suss) The destruction of red blood cells. .