hemoptysis Spitting up blood or blood-tinged sputum from the respiratory tract. Hemoptysis occurs when tiny blood vessels that line the lung airways are broken. Hemoptysis can be harmless such as from irritated bronchial tubes with bronchitis, or be serious such as from cancer of the lung.
hemophilia B Hemophilia due to deficiency of coagulation factor IX in the blood, which results in prolonged oozing after minor and major injuries, tooth extractions, or surgery. There is renewed bleeding after the initial bleeding has stopped. The gene for hemophilia B is on the X chromosome, so males are affected and females carry the…
hemophilia A Classic hemophilia, which is due to a profound deficiency in the activity of clotting factor VIII. Affected individuals suffer hemorrhage into joints and muscles, easy bruising, and prolonged bleeding from wounds. The disease is inherited as an X-linked trait, so males are affected and females carry the gene. Treatment involves administration of blood…
hemophilia An inherited disorder in which the ability of blood to clot normally is impaired. There are two types of hemophilia: hemophilia A and hemophilia B.
hemophagocytic lymphohistiocytosis A rare, cancer-like disorder resulting from an impaired immune system in which macrophages and lymphocytes grow abnormally and accumulate in the body’s organs, including the liver, spleen, bone marrow, central nervous system, and skin. Hemophagocytic lymphohistiocytosis can be an inherited condition, or it can occur as a result of immunosuppression (as in organ…
hemolytic-uremic syndrome A condition involving the breakup of red blood cells (hemolysis) and kidney failure. Abbreviated HUS. HUS is the most common cause of acute kidney failure in infants and young children, but the condition can also occur in adults. The disease results in damage to the lining of blood vessels in the kidney, leading…
hemolytic jaundice, congenital See spherocytosis, hereditary.
hemolytic disease of the newborn Abnormal breakup of red blood cells in a fetus or newborn. Hemolytic disease of the newborn is usually due to antibodies made by the mother that are directed against the baby’s red blood cells. It is typically caused by Rh incompatibility (a difference between the Rh blood groups of mother…
hemolytic anemia Anemia due to the destruction, rather than underproduction, of red blood cells. Hemolytic anemia can result from a medication reaction, from the immune system attacking the red blood cells (autoimmune hemolytic anemia), from destruction of blood cells passing through diseased heart valves, and other causes.
hemolysis Breakage of red blood cells. This occurs to a minor degree normally as red blood cells age. However, excessive hemolysis is very abnormal and leads to hemolytic anemia. See also hemolytic anemia.
hemoglobinuria The presence of free hemoglobin in the urine, which may make the urine look dark. Normally, there is no hemoglobin in the urine. Hemoglobinuria is a sign of a number of abnormal conditions, such as bleeding and paroxysmal nocturnal hemoglobinuria.
hemoglobin S The most common type of abnormal hemoglobin, which is found in people with sickle cell trait and sickle cell anemia. It differs from hemoglobin A only by a single amino acid substitution. The S stands for sickle. See also anemia, sickle cell; sickle cell trait.