25-Hydroxy VD2-D6 is used as an internal standard for the quantification of 25-Hydroxy VD2 (Ercalcidiol, GC13804) by GC- or LC-MS. 25-Hydroxy VD2 is a metabolite of vitamin D2 that reflects the nutritional status of vitamin D in the body.[1]. 25-Hydroxy VD2-D6 can be used as a tracer. In vivo, 25-Hydroxy VD2 is formed from vitamin D2 by the cytochrome P450 (CYP) isoforms CYP2R1 and CYP27A1, and is bound to vitamin D binding protein (DBP) and albumin in the liver, then 25-Hydroxy VD2 is secreted into the bloodstream is transported to the kidney [2]. The serum level of 25-Hydroxy VD2 have been used as a marker to assess the vitamin D status [3].
References:
[1]. Tugcu, Gulcin, Mohammad Charehsaz, and Ahmet Aydın. "Toxicological evaluation of ergocalciferol, cholecalciferol, and their metabolites by a category approach." Drug and Chemical Toxicology 44.6 (2021): 661-667.
[2]. Bikle, D. "Vitamin D: production, metabolism, and mechanisms of action. MDText. com." Inc.: South Dartmouth, MA, USA (2000).
[3]. Saenger, Amy K., et al. "Quantification of serum 25-hydroxyvitamin D2 and D3using HPLC–Tandem Mass Spectrometry and examination of reference intervals for diagnosis of vitamin D deficiency." American journal of clinical pathology 125.6 (2006): 914-920.