Calculation of Biological Variation Components and Reference Change Value for Serum Copper and Zinc

Background: Zinc and copper are among the most important trace elements. Deficiencies of these trace elements cause a wide variety of disorders. The present study aims to report the definitive assessment of biological variation (BV) parameters for these elements as within-subject BV (CVI), between subject BV (CVG), index of individuality (II), and reference change value (RCV) in a Turkish cohort study group. Methods: Ten blood specimens were collected weekly from 20 healthy volunteers (13 women, 7 men) for 10 weeks. Collected sera were stored at -80 degrees C until the time of analysis. Serum zinc and copper levels were analyzed with atomic absorption spectrometry and ANOVA test was used to calculate the variations. Results: The CVI and CVG for zinc were 6.26% and 23.27%, respectively. Analytical variation (CVA) was calculated as 4.24%. II and RCV for zinc were calculated as 0.26 and 21.51%, respectively. The CVI and CVG for copper were 6.05% and 19.64%, respectively. CVA was calculated as 4.24%. II and RCV for copper were calculated as 0.31 and 20.47%, respectively. Conclusions: Since II values were less than 0.6 for both analytes, the reference values will be of little use. RCV might be preferred for better evaluation instead.