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Claudio Marcocci
Department of Clinical and Experimental Medicine, University of Pisa
via Paradisa 2
IT–56124 Pisa (Italy)
E-Mail [email protected]
Giustina A, Bilezikian JP (eds): Vitamin D in Clinical Medicine.
Front Horm Res. Basel, Karger, 2018, vol 50, pp 14–30 (DOI: 10.1159/000486062)
______________________
Daniel D. Bikle
VA Medical Center and University of California San Francisco, San Francisco, CA, USA
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Abstract
The number of requests for vitamin D metabolite measurements has increased dramatically over the past decade leading commercial laboratories to develop rapid high throughput assays. The measurement of 25-hydroxyvitamin D (25[OH]D) and to a lesser extent 1,25-dihydroxyvitamin D (1,25[OH]2D) dominates these requests, but requests for multiple metabolite measurements in the same sample are also increasing. The most commonly used methods include immunoassays and liquid chromatography/mass spectrometry (LC-MS). Each method has its advantages and disadvantages, but with improvements in technology, especially in LC-MS, this method is gaining ascendance due to its greater precision and flexibility. The use of standards from the National Institutes of Standards and Technology has substantially reduced the variability from laboratory to laboratory, thereby improving the reliability of these measurements. Although the current demand is for measurement of total vitamin D metabolite levels, these metabolites circulate in blood tightly bound to vitamin D binding protein
