Understanding Biomarkers

In medicine, biomarker is a that can be used as an indicator of a particular disease state or some other physiological state of an organism. It can be a substance that is introduced into an organism as a means to examine organ function or other aspects of health. For example, rubidium chloride is used as a radioactive isotope to evaluate perfusion of heart muscle. It can also be a substance whose detection indicates a particular disease state, for example, the presence of an antibody may indicate an infection. Biomarkers are characteristic biological properties that can be detected and measured in parts of the body like the blood or tissue.

Biomarkers help in early diagnosis, disease prevention, drug target identification, drug response etc. Several biomarkers have been identified for many diseases such as serum LDL for cholesterol, P53 gene and MMPs for cancer etc. Gene based biomarker is found to be an effective and acceptable marker in the present scientific world.

Biomarkers can be generally classified into two types: Disease-related biomarkers and Drug-related biomarkers. Among these, disease-related biomarkers are again classified into risk indicator or predictive biomarkers, diagnostic biomarkers and prognostic biomarkers.

Predictive biomarkers give an indication of the probable effect of treatment on patient. Diagnostic biomarkers indicates whether the disease already exists in the patient. Prognostic biomarkers explain how such a disease may develop in an individual case regardless of the type of treatment. Thus predictive biomarkers help to assess the most likely response to a particular treatment type, while prognostic markers shows the progression of disease with or without treatment. In contrast, drug-related biomarkers indicate whether a drug will be effective in a specific patient and how the patient’s body will process it.

For chronic diseases, whose treatment may require patients to take medications for years, accurate diagnosis is particularly important, especially when strong side effects are expected from the treatment. In these cases, biomarkers are becoming more and more important, because they can confirm a difficult diagnosis or even make it possible in the first place. A number of diseases, such as Alzheimer's disease or rheumatoid arthritis, often begin with an early, symptom-free phase. In such symptom-free patients there may be more or less probability of actually developing symptoms. In these cases, biomarkers help to identify high-risk individuals reliably and in a timely manner so that they can either be treated before onset of the disease or as soon as possible thereafter.