Introduction: Vitamin D is an important hormone in the human body. He is involved in many physiological body processes. Measuring the level of vitamin D in the patient’s blood is important, diagnostic criteria for identifying and confirming a number of diseases: obesity, hypogonadism, sarcopenia, autoimmune pathologies.
Two methods currently prevail in the laboratory diagnostic market measurement of the level of vitamin D3 in blood plasma: EIA and LC-MS (with its variety - LC-MS / MS).Fundamental differences in the physicochemical nature of these methods are the basis for differing results determined in the same sample.
Objective: In this paper, we set the goal of determining how the results correlate for determining vitamin D3 and its metabolites using the EIA method with the results of determination Pure Vitamin D3 through LC-MS / MS.
Materials and methods: The study was conducted at the clinic of Professor Kalinchenko. Have been selected patients with a clinical picture of vitamin D deficiency. These patients were referred to determination of the level of vitamin D3 using the above methods, subject to preparation rules before analysis. EIA was performed using LC-MS / MS was done using AB SCIEX QTRAP 4500 apparatus connected to Waters Acquity UPLC system. The results were combined for subsequent statistical processing. For a pair of EIA / LC-MS methods, we determined the reliability value of the approximation r ^ 2 and the linear regression equation.
Results: For the presented data, the level of vitamin D3 and its metabolites determined by EIA, and pure vitamin D3, determined by LC-MS, r ^ 2 was 0.9638 (very strong dependence), and the linear regression equation was as follows: LC-MS [nm / ml] = 1.2808 * (EIA) [nmol / ml] + 6.9731.
Discussion: Despite studies by foreign colleagues showing a high level bias and low correlation of results between the EIA and LC-MS methods, our data show a very strong relationship between the two values. By our assumptions, the cause of the various findings is monoclonal antibodies, differing in the global market for reagents for determining the level of hormones derived our linear regression equation allows a practicing endocrinologist to quickly and accurately determine the level of true vitamin D3 in the patient.