Clinical biochemistry is a medical field where chemistry, physiological chemistry and molecular biology methods are applied to examine blood, urine, cerebrospinal fluid, and other bodily fluids for biomarkers in order to prevent, diagnose, and follow up treatment of diseases. The field also includes studies of biochemical processes in both healthy and sick individuals. The analysis are based on principles of chemistry, biotechnology, and physiological chemisty, and utilise many different methods based on enzyme reactions, electrochemistry, antigen-antibody reactions, mass spectometry, and flow cytometry principles. The analysis have strict requirements that use statistical tools before (pre-analytical), during (analytical), and after (post-analytical) an examination is completed for quality assurance.