Blood is composed of cells and plasma (or serum), a liquid that is normally pale yellow in colour and transparent. Devices that analyze serum specimens (biochemistry tests) monitor three aspects of serum: lipemia, icterus index and hemolysis index.
The hemolysis index is a measurement of the red colour of serum. This colour is normally due almost exclusively to the presence of hemoglobin, which comes from ruptured red blood cell membranes. The hemolysis index is expressed as a number of “plus” signs (from zero to ++++). A hemolysis index of zero is normal. A non-negative result (+ to ++++) indicates an abnormal concentration of hemoglobin, which may be due to pathological causes (hemolytic disease), but it also frequently reflects abnormal specimen preparation. In some patients, the red blood cell membrane is more fragile and an abnormally high number of red blood cells break at the time of collection (traumatic sampling, particularly when using the micromethod in young children) or during the process of stabilizing the specimen by centrifugation. Check your blood count results, if applicable, for abnormalities related to hemolytic syndromes. The presence of hemolysis also indicates that elements normally contained in the red blood cells are present in the serum. Hemolysis levels of ++ to ++++ will therefore interfere with other tests by causing increased results for potassium, iron, LDH and folic acid.