Estimating Reference Change Values Using Routine Patient Data: A Novel Pathology Database Approach.

Background: The reference change value (RCV) is calculated by combining the within-subject biological variation (CVI) and local analytical variation (CVA). These calculations do not account for the variation seen in preanalytical conditions in routine practice or CVI in patients presenting for treatment. As a result, the RCVs may not reflect routine practice or align with clinicians' experiences.

Sex Hormones and Adrenal Steroids: Biological Variation Estimated Using Direct and Indirect Methods.

Background: Biological variation (BV) data may be used to develop analytical performance specifications (APS), reference change values (RCV), and support the applicability of population reference intervals. This study estimates within-subject BV (CVI) for several endocrine biomarkers using 3 different methodological approaches.

Methods: For the direct method, 30 healthy volunteers were sampled weekly for 10 consecutive weeks.