Measurement of Vitamin D in Monitoring Patients Treated with Vitamin D2 (ergocalciferol) or D3 (cholecalciferol)

BOZZO G; REPETTO EM; BONELLI AL; FENILI C; DAMILANO S

Boston

Congreso; Endocrine Society's 98th Annual Meeting - ENDO 2016; 2016

The Endocrine Society

Measurement of 25(OH)Vitamin D is indicative of nutritional status or bioavailability of Vitamin D. The methods used have different specificity that lead to discrepancies between results. Objectives. 1-Evaluate levels of vitamin D by 2 methods (reactivity to D2+D3 forms) in serum from medication-free patients (NS) and with D2 (SD2)- or D3 (SD3)-treated patients. 2-Evaluate the bias between the methods, depending on the dose and the time elapsed since the last drug administration (dose/time relationship). Materials and methods. Serum samples from 238 patients were used: 59 NS, 67 SD2 (Raquiferol) and 112 SD3 (Sterogyl® n=46; Oravil® n=40; Osteodyn® n=26) were studied. Levels of 25(OH)D was measured with a chemiluminescent (QLIA,Liaison-Diasorin) and with an electrochemiluminescent method (EQLIA,Cobas E411, Roche). Dose/time from the last administration ratio was calculated: ((nº of drops of D2 or 100000U of D3)/days post dose). Statistics.Coefficient of correlation (Pearson). Regression analysis and the bias was evaluated (Bland-Altman´s plot). Results. 25(OH)D: mean, range (ng/mL): NS: EQLIA: 32.3(12.2-53.3); QLIA: 28.5(12.4-52.3); SD2 Raquiferol: EQLIA: 38.7(20.0-57.2); QLIA: 35.5(20.4-64.2); SD3 Sterogyl: EQLIA: 43.61(25.5-59.1); QLIA: 35.1(21.5-65.9); SD3 Oravil: EQLIA 42.9 (28.3-62.0); QLIA: 33.92(22.1-62.3); SD3 Osteodyn: EQLIA: 45.7(23.2-65.4); QLIA: 37.1(14.4-57.8). Level of agreement between methods: 25(OH)D EQLIA vs QLIA: NS: r=0,758;p=0,0001; Bias: 3.8(-7.8-15.4).SD2 Raquiferol:r=0,680;p=0,0001;Bias:3.1(-11.0-17.3).SD3 Sterogyl:r=0,440;p=0,0023; Bias: 8.5(-10.2-27.2). SD3 Oravil:r=0,496;p=0,0001; Bias: 8.9(-6.7-24.5).SD3 Osteodyn:r=0,560;p=0,0029; Bias: 8.6(-12.2-29.4). Correlation and agreement is observed between the results by the 2 immunoassays in NS and SD2 groups, and are lost in D3 substituted groups. Differences in function of the dose/time: SD2 Raquiferol:(y=3.2375-0.03942x); SD3 Sterogyl: (y=13.9164-235.7252x); SD3 Oravil: (y=17.0710-346.7049x); SD3 Osteodyn: (y=11.0235-68.4446x). Our results show that, the deviations between the immunoassays were smaller with decreasing dose/time post administration relationship. Conclusions. The methods evaluated detected the endogenous form of D and the D2 supplementation similarly. However, there were different degrees of reactivity with the molecular forms present in the serum from D3 supplemented patients. The treatment effect on the analytical process is corroborated by observing a greater deviation in higher doses and/or less time after administration. Our results agree with those found by other authors and those observed in the Control Programs for International Quality Vitamin D (eg. UK, DEQUAS). A need of a harmonization of methods is reaffirmed and mean while, emphasized the importance of monitoring of patients with the same methodology.