In medicine, a biomarker is an indicator of a particular disease state or a particular state of an organism.

For other uses of the term, see Biomarker (disambiguation).

An NIH study group committed to the following definition in 1998: "a characteristic that is objectively measured and evaluated as an indicator of normal biologic processes, pathogenic processes, or pharmacologic responses to a therapeutic intervention." ^[1]

In the past, biomarkers were primarily physiological indicators such as blood pressure or heart rate. More recently, biomarker is becoming a synonym for molecular biomarker, such as elevated prostate specific antigen as a molecular biomarker for prostate cancer. Biomarkers also cover the use of molecular indicators of environmental exposure in epidemiologic studies such as human papilloma virus or certain markers of tobacco exposure such as 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Physiology (in Greek physis = nature and logos = word) is the study of the mechanical, physical, and biochemical functions of living organisms. ... Blood pressure is the pressure exerted by the blood on the walls of the blood vessels. ... Heart rate is a term used to describe the frequency of the cardiac cycle. ... Prostate specific antigen (PSA, also known as kallikrein III, seminin, semenogelase, γ-seminoprotein and P-30 antigen) is a protein manufactured almost exclusively by the prostate gland; PSA is produced for the ejaculate where it liquifies the semen and allows sperm to swim freely. ... Prostate cancer is a disease in which cancer develops in the prostate, a gland in the male reproductive system. ... Epidemiologic studies are generally categorized as descriptive, analytic (aiming to examine associations, commonly hypothesized causal relationships), and experimental (a term often equated with clinical or community trials of treatments and other interventions). ... Human papillomavirus (HPV) is a virus which affects humans. ...

References

1. ^ Biomarkers and surrogate endpoints: preferred definitions and conceptual framework. Clinical Pharmacology & Therapeutics, Volume 69, Issue 3, March 2001, Pages 89-95: (2001). Retrieved on April 1, 2006.