A biomarker is "a characteristic that is objectively measured and evaluated as an indicator of normal biological processes, pathogenic processes or pharmacological responses to a therapeutic intervention.

Biomarkers are the measures used to perform a clinical assessment such as blood pressure or cholesterol level and are used to monitor and predict health states in individuals or across populations so that appropriate therapeutic intervention can be planned.

Biomarkers may be used alone or in combination to assess the health or disease state of an individual.

There are two major types of biomarkers: biomarkers of exposure, which are used in risk prediction, and biomarkers of disease, which are used in screening and diagnosis and monitoring of disease progression. Biomarkers used in risk prediction, in screening, and as diagnostic tests are well established, and they offer distinct and obvious advantages. The classification of many neurological diseases is based on either standardized clinical criteria or histological diagnoses. Biomarkers also have the potential to identify neurological disease at an early stage, to provide a method for homogeneous classification of a disease, and to extend our knowledge-base concerning the underlying disease pathogenesis. These advantages have direct application to all types of clinical investigation, from clinical trials to observational studies in epidemiology.

Benefits of biomarkers in medicine
• In medicine, biomarkers are often compounds isolated from serum, urine, or other fluids that can be used as an indicator of the presence or severity of a particular disease state.
• Biomarkers can also be used to assess the effectiveness of particular therapies in ameliorating the effects of a disease.
• By using easily obtained and assayed biomarkers to monitor a patient's reaction to a particular drug, it is possible to determine whether treatment is effective for that individual by measuring drug response rate or toxic effects associated with the drug.
• Biomarkers can be used to detect a change in the physiological state of a patient that correlates with the risk or progression of a disease or with the susceptibility of a disease to a given treatment.

Practice question:

1. Which of the following is/are the characteristic feature of an ideal biomarker?
1. It should be safe and easy to measure
2. It should be cost efficient
3. It should be consistent across gender and ethnic groups


a) Only 1

b) 1 and 2

c) 2 and 3

d) All

Ans: d
Exp: An ideal biomarker has certain characteristics that make it appropriate for checking a particular disease condition. Ideally, an ideal marker should have the following features:

a) Safe and easy to measure
b) Cost efficient to follow up
c) Modifiable with treatment
d) Consistent across gender and ethnic groups