Determination of individuality index and reference change value in the parameters that is used to evaluate the calcium metabolism

AİM: In this study, it is aimed to determine the reference change value (RCV) and serum calcium, phosphor, magnesium, PTH, 25(OH) Vitamin D and calcitonin individuality index (II) that is used to evaluate the calcium metabolism. MATERIALS AND METHODS: Five samples taken from 20 healthy volunteers (10 women, 10 men), who are between the ages of 19 and 52, on day 0, day 1, day 7, day 14 and day 28 in a one-month period were studied twice to eliminate the analytic variation between days. Control serums at different levels were studied twice for the study parameters of biological variation. Analytic variation (CVA), intra biological variation (CVI) and interpersonal biological variation (CVG) values were calculated by using the arithmetic mean and standard deviation found for the evaluated parameters. II and RCV values were derived with these calculated values. Data were analyzed using the CV-ANOVA statistic program. RESULTS: Individuality index was calculated as 0.12 for calcium, 0.85 for phosphor, 0.17 for magnesium, 0.09 for PTH, 0.39 for 25(OH) Vitamin D and 1.26 for calcitonin; and RCV values were calculated as (95%/99%) 3.5/4.6; 5.0/6.5; 8.0/10.5; 14.3/18.8; 27.8/36.6; 18.7/24.6 respectively. CONCLUSIONS: Because the II values calculated for calcium, magnesium, PTH and 25(OH) Vitamin D were less than 0.6; employing RCV may be more appropriate than employing the population based reference range for these parameters. However, since the calculated values of II for phosphor and calcitonin were between 0.6 and 1.4, using both population based reference interval and RCV values may be appropriate for these parameters. Considering the lack of data in the BV database for many parameters such as the 25(OH) Vitamin D and calcitonin that we evaluated in our study, we believe that more comprehensive studies are needed to similarly contribute to the database and encourage further employment of RCV.