Matthew Smith

Vitamin D is a fundamentally important hormone involved in calcium absorption, bone mineralization and parathyroid hormone production. Vitamin D deficiency may result in a myriad of diseases, such as osteomalacia, rickets and has more recently been identified as a risk factor for diabetes. Accurate determination of serum vitamin D levels is, therefore, paramount when assessing an individual for related pathologies against an appropriate reference range for interpretation. The purpose of this study was to assess vitamin D status between ‘healthy’ Caucasian and ‘healthy’ Asian populations of Peterborough, taking into account seasonal serum vitamin D variation. In addition, we evaluated whether a reference range for serum vitamin D of the local population should be race and/or seasonal specific. Using a Chromsystems high-pressure liquid chromatography vitamin D2/D3 methodology upon Agilent 1100 hardware, serum vitamin D status was assessed in 200 subjects of varying age, gender and ethnicity using summer (n = 106) and winter (n = 94) cohorts. Serum vitamin D3 levels were significantly lower (up to 70%; P ≤ 0.0001) in both men and women of the Asian population in comparison to the Caucasian population during both the summer and winter periods. Vitamin D3 levels of the Caucasian cohort displayed significant variation between summer and winter (P≤0.0001), while the overall Asian population displayed no significant seasonal variation in vitamin D status. The reference range produced by the Caucasian cohorts (8.2–53.7 µg/l) complements published studies, while the Asian cohort displayed significantly lower limits (3.6–26.7 µg/l). Currently, no genetic predisposition to lower vitamin D status in Asians compared with Caucasians has been established. Therefore, the Caucasian range was implemented for all ethnicities, as this conforms to the national consensus of deficiency within the UK. This reference range indicates that 34% of the ‘healthy’ Asian community are vitamin D deficient compared with 2% of Caucasians. Further research is required to increase vitamin D deficiency awareness in Asian communities and highlight the potential role of supplementation.