Significance of Serum 24, 25-Dihydroxyvitamin D in the Assessment of Vitamin D Status: A Double-edged Sword?. (6th January 2020)

• Record Type: Journal Article
• Authors: Cashman, Kevin D; Hayes, Aoife; Galvin, Karen; Merkel, Joyce; Jones, Glenville; Kaufmann, Martin; Hoofnagle, Andrew N; Carter, Graham D; Durazo-Arvizu, Ramon A; Sempos, Christopher T
• Is Part Of: Clinical chemistry. Volume 61:Number 4(2015)
• Page Start: 636
• Page End: 645
• Publication Date: 2020-01-06
• Subjects: Clinical chemistry -- Periodicals; Pharmaceutical chemistry -- Periodicals; Biochemistry -- Periodicals; Biochimie -- Périodiques; Diagnostics biologiques -- Périodiques; Biochemistry; Clinical chemistry; Pharmaceutical chemistry; Biochemistry; Laboratory Techniques and Procedures; Klinische chemie; Periodicals; 616.075605
• DOI: 10.1373/clinchem.2014.234955
• Languages: English
• ISSNs: 0009-9147

Abstract

Abstract: BACKGROUND: 24, 25-Dihydroxyvitamin D [24, 25(OH)2 D] in serum may be both a nuisance and nutritionally valuable. METHODS: We investigated the impact of 24, 25(OH)2 D3 on the performance of commercially available immunoassays for serum total 25-hydroxyvitamin D [25(OH)D] using ( a ) serum from a nationally representative sample of adults, ( b ) serum from a spiking experiment, and ( c ) data from the UK Vitamin D External Quality Assurance Scheme (DEQAS). We also investigated the utility of the serum ratio of 24, 25(OH)2 D3 to 25(OH)D as an index of inactivation and of response to vitamin D supplementation using randomized controlled trial (RCT) data. Measurement of 24, 25(OH)2 D in sera by a LC-MS/MS method allowed for an investigation of its impact on immunoassay-derived serum 25(OH)D values as well as its clinical utility. We report data from a nationally representative sample of adults, a recent vitamin D RCT in older adults, and DEQAS. RESULTS: 24, 25(OH)2 D3 contributed to the positive bias observed in some immunoassays relative to LC-MS/MS-derived estimates for total 25(OH)D. A spiking experiment showed that the degree of cross-reactivity with 24, 25(OH)2 D was high and may underpin this positive bias. Adjustment for 24, 25(OH)2 D3 concentration brought estimates closer to true values. Data from the vitamin D RCT showed that the ratio of 24, 25(OH)2 D3 to 25(OH)D was associated with serum 25(OH)D3 and with response of serum 25(OH)D to vitamin D supplementation. CONCLUSIONS: Our findings highlight that the effect of 24, 25(OH)2 D3 in serum is a double-edged sword—an interferent for some immunoassays, yet potentially informative of nutritional status.