Clinical diagnostic tools for vitamin D assessment. Issue 180 (June 2018)

• Record Type: Journal Article
• Authors: Shah, Iltaf; Akhtar, M. Kalim; Hisaindee, Soleiman; Rauf, Muhammad A.; Sadig, Mohammed; Ashraf, S. Salman
• Is Part Of: Journal of steroid biochemistry and molecular biology. Issue 180(2017)
• Page Start: 105
• Page End: 117
• Publication Date: 2018-06
• Subjects: Immunoassays -- Vitamin D -- HPLC -- LC/MS/MS; Steroid hormones -- Periodicals; Biochemistry -- Periodicals; Hormones -- Periodicals; Molecular Biology -- Periodicals; Hormones stéroïdes -- Périodiques; Steroid hormones; Periodicals; 572.579
• DOI: 10.1016/j.jsbmb.2017.10.003
• Languages: English
• ISSNs: 0960-0760

Abstract

Graphical abstract: Highlights: Immunoassays are rapid, high throughput offering excellent sensitivity of 3.4–156 ng/ml, but cannot distinguish between forms of vitamin D. HPLC based assays are cheaper and cost-effective, but they are not very sensitive for minor Vitamin D metabolites. LC/MS/MS also provides excellent sensitivity, wide dynamic range from 0.068 pg/ml to 100 ng/ml, along with accurate metabolite identification. A huge limitation with LC/MS/MS is their poor throughput for sample analyses making them impractical for rapid, large-scale analyses. Recently, attention has been focused on accurately measuring various active and inactive epimers and isobars of vitamin D. Abstract: Vitamin D deficiency has been implicated in a plethora of diseases including rheumatoid arthritis, Parkinson's disease, Alzheimer's disease, and osteoporosis. Deficiency of this vitamin is a global epidemic affecting both developing and developed nations. Within a clinical context, the qualitative and quantitative analysis of vitamin D is therefore vital. The main metabolic markers for assessing vitamin D status in humans are the hydroxylated forms of vitamin D, 25OHD3 and 25OHD2 on account of their long half-lives within the body and excellent stability. An adequate level for healthy individuals of these hydroxylated forms is estimated to be around 20–40 ng/ml of blood. There are three main analytical techniques for determining the levels of 25OHD3 and 25OHD2 . The first technique is immunoassay-based and can be performed in a rapid, high throughput, automated manner, allowing as many as 240 tests per hour with the duration of each assay as little as 18 min. Furthermore, it offers excellent sensitivity with a detection range of 3.4–156 ng/ml. A major downside of immunoassays is that they are unable to distinguish between the various forms of vitamin D. While HPLC is a highthroughput low cost instrument it is not a very sensitive technique and cannot quantify the down stream metabolites of vitamin D. The third technique, namely liquid chromatography-mass spectrometry (LC–MS/), provides excellent sensitivity with a wide dynamic range from 0.068 pg/ml to 100 ng/ml. Additionally, it offers a high level of separation and permits identification of vitamin D-related metabolites. However, a huge limitation with LC/MS/MS is their poor throughput for sample analyses. As yet, there is no analytical technique which combines the fine detection capabilities of LC/MS/MS and the rapid, automated format of immunoassay, for vitamin D analyses. Future attention therefore needs to be given to this area if the current clinical diagnostic tools for vitamin D analysis are to be further improved.