Variation in clinical biochemistry; biological variation

Aim: With the state of art, analytical error and variation sources are gradually reduced in total test process, pre-analytical error and variation sources can be reduced by systematic quality management and training. In the evaluation of the individual test results, possible sources of variation arising from the pre-analysis process are tried to be minimized and practically neglected, and natural random variation-in-subject biological variation and analytical variation data are used in the evaluation of the outcome. For this reason, studies of biological variation of laboratory analytes are of increasing interest. The reason for this trend is that in all laboratory processes associated with potential practical applications of this knowledge. Biological variation data allows derivation of important data for the interpretation and use of laboratory tests such as the estimation of the individuality index for assessing the use of population-based reference intervals for test interpretations, the prediction of significant changes occurring in repetitions of test results within the reference interval. In this study, we aimed to obtain intra-individual and intra-individual BV data of the Iron, Transferrin, Ferritin, Vitamin B12, Folate and Vitamin D tests which were evaluated by comparing the results with the population-based reference intervals. And also we aimed to obtain the individuality index and reference change value, based to reference intervals with using of these values Materials and Methods: 21 (11 female, 10 male) healthy individuals age between 22-50 years were included in the study to determine the intra-individual biological variation components and the reference change values for Iron, Transferrin, Ferritin, Vitamin B12, Folate and Vitamin D tests. A total of 5 venous blood samples were taken at 0.1.7.14.and 28th days within one month. All tests were performed in the autoanalyzer and CVI, CVG, II, RCV values were calculated in the both genders and all of the groups. Results: BV data for all the parameters in all the groups are; CVA (%) / CVI (%) / CVG (%) Iron, 0.67 / 27.3 / 32.3 Transferrin, 0.62 / 3.60/10.24 Ferritin, 2.27 / 6.21 / 105.6 Folate 4.71 / 10.3 / 28.56 Vitamin B12, 6.16 / 5.77 / D Vitamin 3.44 / 8.21 / 54.9 respectively. RCV calculated as a 2-tailed value at level of probability of significant change set at 0.95 - 0.99; 74.9 / 98.7 10.1 / 13.3 18.3 / 24.1 31.4 / 41.3 23.4 / 30 , 8 24,7 / 32,5 and individuality indices were 0.8 0,4 0,1 0,4 0.17 0,1 respectively. Conclusion: CVI and CVG values for Iron, Transferrin, Folate, Vitamin B12, 25-OH Vitamin D are in accordance with the literature. The CVI and CVG values for ferritin were calculated differently from the values in the database. This difference might be due to the characteristics of selected individuals for study. Evaluating the suitability and utility of the use of RA with values found for II; For iron, the use of RA was appropriate when taken as II <0.6 and II> 1.4, and for Transferrin, Folate, Vitamin B12, 25-OH Vitamin D the use of RCV is better than the use of RA. Keywords: Preanalytic variation, Analytic variation, Within and between-subject biological variation, Reference change value, Individuality index.