Clinical Chemistry Basics Variables affecting chemistry test results Many factors other than disease influence the results of chemistry tests. These factors may be preanalytical, analytical and post-analytical. Preanalytical variables are variables associated with the patient, sample collection and sample handling. These generally affect the composition of the body fluid before analysis.
Analytical variables are factors which influence the analytical procedure.
Post-analytical variables involve the different ways data from the laboratory is presented, stored and transferred to the clinician. Whenever possible, these variables should be controlled in order to minimize their effect on test outcome. For more information on the variables that affect test results, click on the title of the variable in the side menu.