The VitDAL have developed an ultra-high performance liquid chromatography – mass spectrometry (UHPLC-MS) assay to accurately key vitamin D metabolites in serum and plasma. These assays are critically important to the VitDAL research programme and are also available as an external service to collaborators and clinicians. We have established a methodology which allows us to accurately quantify the major vitamin D metabolite, 25-hydroxyvitamin D (25(OH)D), which is widely used to assess vitamin D status. We have also developed a UHPLC-MS system  to allow us to accurately measure several other biologically relevant vitamin D metabolites, notably C-3 epimers of 25-hydroxyvitamin D, which have been previously shown to interfere with 25(OH)D measurements. We have also defined a reference range for free 25(OH)D concentrations in dogs. A paper describing some of our key assay development work can be found at the following link. This service aims to provide a robust, multi-species approach to assess vitamin D status that will not only support our research into vitamin D biology but will also provide clinically relevant data which will assist in patient management.

VitDAL submission form (Word doc, 127KB)

VitDAL submission form (PDF, 153KB)


Our 25(OH)D assay has been accredited by the Vitamin D External Quality Assessment Scheme (DEQAS) in 2019 and 2020. The DEQAS programme assesses the performance of vitamin D metabolite assays and only assays whose results are within stringent performance metrics are accredited by the scheme. 

If you would like to use the VitDAL assay service please contact Professor Richard Mellanby at or use the contact page on the VitDAL website. Please submitted samples from fasted patients to avoid lipaemia related assay interference.