Abstract
25-Hydroxyvitamin D3 3β-sulphate has been identified in human plasma. The compound was isolated by anion-exchange chromatography and following hydrolysis it was characterized by high-performance liquid chromatography and gas chromatography-mass spectrometry. The mean concentration of sulphated 25-hydroxy vitamin D3 in plasma from 60 patients was 16.7 ±7.1 ngml and the levels often exceeded those of the corresponding free compound. The study also shows that unconjugated 25-hydroxvitamin D3 is not readily sulphated by man in vivo