Hemoglobinemia is a medical condition characterized by the presence of excess free hemoglobin in the blood. Some of the synonyms for hemoglobinemia include hemoglobulinuria, intravascular hemolysis, and plasma hemoglobin. Hemoglobulinuria refers to the presence of hemoglobin in urine due to the breakdown of red blood cells releasing free hemoglobin. Intravascular hemolysis is a condition where the red blood cells are destroyed inside the blood vessels, leading to the release of free hemoglobin in the bloodstream. Plasma hemoglobin is a term used to describe the presence of free hemoglobin in the blood plasma due to the lysis of red blood cells. These synonyms are useful in medical literature and in the diagnosis of this medical condition.