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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 aspect of the serum: lipemia, icterus index and hemolysis index.

Icterus (or the icterus index) is a measure of the yellow colour of serum. This colour is normally due almost exclusively to the presence of bilirubin, a hemoglobin waste product from the red blood cells. The icterus index is expressed as a number of “plus” signs (from zero to ++++). An icterus index of zero is normal. A non-negative result (+ to ++++) indicates a concentration of bilirubin above the normal value. To better understand what these results mean, see your bilirubin result. Very high results (++++) can interfere with certain laboratory tests. More rarely, a high icterus index can be caused by excessive consumption of foods like carrots or vitamin supplements containing beta carotene.

Term of the Week

Predictive medicine

Medicine that links medical knowledge with data to predict a patient’s potential health problems. Examples include artificial intelligence and genetics.