|polycythaemia or esp (US) polycythemia (ˌpɒlɪsaɪˈθiːmɪə)|
|an abnormal condition of the blood characterized by an increase in the number of red blood cells. It can occur as a primary disease of unknown cause (polycythaemia vera or erythraemia) or in association with respiratory or circulatory diseases|
|[C19: from |
|polycythemia or esp (US) polycythemia|
|[C19: from |
polycythemia pol·y·cy·the·mi·a (pŏl'ē-sī-thē'mē-ə)
A condition characterized by an abnormal increase in the number of red blood cells in the blood. Also called erythrocythemia, hypercythemia, hypererythrocythemia, hyperglobulia.
|the offspring of a zebra and a donkey.|
|an arrangement of five objects, as trees, in a square or rectangle, one at each corner and one in the middle.|
abnormal increase in red blood cells and hemoglobin in the circulation, a situation that results in thickened blood, retarded flow, and an increased danger of clot formation within the circulatory system. Polycythemia may be relative (e.g., after blood-plasma loss), transient (as when a large number of red blood cells suddenly enter the circulation from storage), or absolute (i.e., reflecting an increase in actual mass of red cells in the body). Relative and transient, or secondary, polycythemia disappear when the condition to which they are secondary is eliminated. Absolute polycythemia, when the cause is known, is called erythrocytosis; this may accompany congenital heart disease, some hemoglobin defects, pulmonary disease (e.g., emphysema, silicosis), the Pickwickian syndrome (a form of obesity), and living at high altitudes.
Learn more about polycythemia with a free trial on Britannica.com.