Controversias en la medición de 25 (OH) Vitamina D: comparación de dos metodologías

introduction: the methods used for vitamin d measurement have several methodological aspects still not defined, such as reference method, traceability of international standard, specificity, etc, which generates great discrepancies between the results obtained. objective: to compare the results of vitamin d measurements obtained with two different immunoassays of different specificity and standardization, and their impact on clinical interpretation in patients treated and not treated with vitamin d2 or d3. materials and methods: two groups are considered for comparison of the methods: g1 (95 serum samples from patients who were receiving vitamin d2, vitamin d3 or no medication) and g2 (40 serum samples after excluding the 55 patients who received vitamin d2). results: there are great differences between the samples measured by both assays. we found highly significant differences between means in g1 (p <0.0001) and significant differences in g2 (p < 0.0038). no correlation was observed between eqlia vs. ria in the g1 (r = -0.00671, p = 0.9483) but good correlation in g2. (r = 0.898, p < 0.0000). although eclia was in agreement with ria, in g1 the results of the methods shows a wide dispersion around the mean of the difference 20.8 ng / ml. in contrast, in g2 there is a better match between results (mean of the difference 6.4 ng/ml). conclusions: this comparison of methods allowed us to identify two critical situations to consider when measuring vitamin d: first, whether the patient has been supplemented or not with vitamin d, and in that case, if he/she has been given d2 or d3, and secondly, the method used for measurement. discrepancies between the results of vitamin d measurements obtained by different methodologies will impact on the clinical usefulness of the report issued by the laboratory, and consequently in the interpretation and medical decision.