Evaluation of the analytical performance of two vitamin D immunoassay methods

Abstract

Evaluation of the analytical performance of two vitamin D immunoassay methods V itamin D is a regulatory, bone-stimulating vitamin that has a role in the absorption of calcium and inorganic phosphorus from the intestine. A deficiency is known to be a risk factor for osteoporosis [1]. The importance of vitamin D deficiency in many chronic diseases, including cancer, diabetes, hypertension, and asthma, as well as bone, liver, and kidney diseases has also been demonstrated in recent studies [2, 3]. This has increased the demand for a 25-hydroxyvitamin D [25(OH)D] test as a routine measurement in clinical laboratories [4]. Among the analytical techniques used in vitamin D measurement are a radioimmune assay, enzyme-linked immunosorbent assay, chemiluminescence immunoassay, and chemiluminescence microparticle immunoassay methods, including a competitive immunoassay, competitive protein-binding measurement, non-immunological high performance liquid chromatography performed directly after chromatographic separation, and liquid chromatography using tandem-mass spectrometry (LC-MS/MS) [5]. The poor antibody selectivity of immunoassay methods results in significant differences in various 25(OH)D measurements through cross-reaction with other vitamin D metabolites, as well as serum matrix components, such as lipids [6, 7]. In recent years there has been discussion of reference methods and reference standards to improve the quality of 25(OH) D testing [3]. Standardization of the 25(OH)D test is a global problem [8]. The Architect 5P02 25(OH)D test (Abbott Labo-Objectives: The increasing clinical significance of 25-hydroxyvitamin D [25(OH)D] has made it an indispensable test in the laboratory. The aim of this study was to investigate the analytical performance of 2 widely used immunoassay methods, the new Abbott Architect 5P02 25-OH Vitamin D assay (Abbott Laboratories, Lake Bluff, IL, USA) and the Beckman Coulter product, the Access 25 (OH) Vitamin D Total assay (Beckman Coulter, Inc., Brea, CA, USA). Methods: A total of 96 serum samples were used to compare the accuracy, linearity, limit of blank, limit of detection, limit of quantification, and precision of the 2 tests using the Architect i2000SR System (Abbott Laboratories, Lake Bluff, IL, USA) and the Access2 (Beckman Coulter, Brea, CA, USA) immunoassay platform. Deming regression analysis and Bland Altman graphs were used to compare the 2 methods. Results: The within-run coefficient of variation (CV%) of the Architect and the Access systems was <3.1% and <6.72%, respectively. There was good linearity of the 25(OH)D measurement at 98.9-114% for the Architect assay and 94.1-103.5% for the Access assay at concentrations of 5-160 ng/mL and 6.2-210.4 ng/mL, respectively. The correlation coefficient was 0.921 (y=-2.1+0.97x). Conclusion: Thorough testing indicated that the new 5P02 Abbott Architect 25(OH)D and the Beckman Coulter Ac-cess2 25(OH)D Total test demonstrated appropriate analytical performance.

Serum vitamin D level in patients with schizophrenia: A community-based study

“…The serum samples were stored at −80°C. Vitamin D was measured using chemiluminescent immunoassay (Beckman Coulter Immunoassay Systems #B24838, USA) with a Beckman Access 2 system (Beckman Coulter, USA) 14 . Serum 25(OH) vitamin D3 level <20 ng/ml was considered deficient while 21-29 ng/ml was considered insufficient 15 .…”