A diagnostic biomarker refers to a biological parameter that aids the diagnosis of a disease and may serve in determining disease progression and/or success of treatment. It may be a laboratory, radiological, genetic, anatomical, physiological or other finding that helps to differentiate one disease from others. Diagnostic biomarkers are used to confirm that a patient has a particular health disorder. Identifying biomarkers that allow earlier or more accurate detection of disease is a major endeavor of biomedical research. Despite billions of dollars spent on research to develop new diagnostic tests based in biomarkers, most are still only classified as “promising. Analytical and clinical factors can make test validation challenging. Sample collection, storage, and handling can influence test results and introduce bias to diagnostic studies, yet most discovery research pays little attention to these details. Analytical and postanalytical phases (data interpretation dealing with aspects such as small sample size or lack of clinical and sociodemographic patient information) can also influence test implementation