title: Deciding the optimum interval between specimen collections: theory and nomograms.
abstract: The time interval between collection of specimens from an individual patient is usually determined empirically. For analytes whose values decline according to first-order kinetics--for example, enzyme activities in serum after an acute myocardial infarction, tumor markers in serum after excision of the tumor, and drugs in serum after an overdose--the minimum time between collections (delta T) depends on the elimination half-life (t) and the analytical precision (CVA), according to the equation: delta T = (1/log2) X t X log (2.33 CVA/100 + 1). Nomograms showing this relationship graphically have been generated.
mesh_terms: D000951:Antigens, Neoplasm / Q000032:analysis; D001800:Blood Specimen Collection; D004798:Enzymes / Q000097:blood; D006207:Half-Life; D006801:Humans; D007700:Kinetics; D008954:Models, Biological; D004364:Pharmaceutical Preparations / Q000097:blood; D013223:Statistics as Topic
chemical_list: D000951:Antigens, Neoplasm; D004798:Enzymes; D004364:Pharmaceutical Preparations