Glossary of Pharmacology 

Biological marker (biomarker)

A biomarker is a defined medical indicator that can be measured accurately and reproducibly, and serves to define normal biological processes, pathogenic responses to exposure or results of intervention. Biomarkers are different from medical symptoms (i.e. clinical outcome assessment), which are perceived by the patients themselves in terms of how they feel, function, or survive. Biomarkers serve a variety of purposes, one of which is prediction of clinical outcome.

Biomarkers include everything from basic readily measured parameters such as pulse and blood pressure to more complex laboratory tests of blood and other tissues. For instance, high systolic blood pressure is linked to stroke and lower systolic blood pressure is clinically advantageous. A second example might be: elevations in serum levels of calcitonin, a hormone produced and released from thyroid gland, can be an indicator of medullary thyroid cancer. The use of tyrosine kinase inhibitors such as Cabozantinib and Vandetinibin treatment of thyroid carcinomas can lower and normalize calcitonin serum levels. 

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