Hemoglobinemia is a medical condition in which there is an excess of hemoglobin

Hemoglobin

Hemoglobin is the iron-containing oxygen-transport metalloprotein in the red blood cells of all vertebrates, with the exception of the fish family Channichthyidae, as well as the tissues of some invertebrates...

 in the blood plasma

Blood plasma

Blood plasma is the straw-colored liquid component of blood in which the blood cells in whole blood are normally suspended. It makes up about 55% of the total blood volume. It is the intravascular fluid part of extracellular fluid...

. This is an effect of intravascular hemolysis

Hemolysis

Hemolysis —from the Greek meaning "blood" and meaning a "loosing", "setting free" or "releasing"—is the rupturing of erythrocytes and the release of their contents into surrounding fluid...

, in which hemoglobin separates from red blood cells, a form of anemia

Anemia

Anemia is a decrease in number of red blood cells or less than the normal quantity of hemoglobin in the blood. However, it can include decreased oxygen-binding ability of each hemoglobin molecule due to deformity or lack in numerical development as in some other types of hemoglobin...

. Hemoglobinemia can be caused by intrinisic or extrinsic factors. When hemoglobinemia is internally caused, it is a result of recessive genetic defects that cause the red blood cells to lyse

Lysis

Lysis refers to the breaking down of a cell, often by viral, enzymic, or osmotic mechanisms that compromise its integrity. A fluid containing the contents of lysed cells is called a "lysate"....

, letting the hemoglobin spill out of the cell into the blood plasma. In externally caused hemoglobinemia, an outside attacker acts as an antibody against the red blood cells. This can cause the cells to be destroyed and their hemoglobin released.