In medicine, a biomarker is a measurable indicator of the severity or presence of somedisease state. More generally a biomarker is anything that can be used as an indicator of aparticular disease state or some other physiological state of an organism.
A biomarker can be a substance that is introduced into an organism as a means to examineorgan function or other aspects of health. For example, rubidium chloride is used in isotopiclabeling to evaluate perfusion of heart muscle. It can also be a substance whose detectionindicates a particular disease state, for example, the presence of an antibody may indicatean infection.