NHANES Monitoring of Serum 25-Hydroxyvitamin D: A Roundtable Summary

Abstract

A roundtable to discuss monitoring of serum 25-hydroxyvitamin D [25(OH)D] in the NHANES was held in late July 2009. Topics included the following: 1) options for dealing with assay fluctuations in serum 25(OH)D in the NHANES conducted between 1988 and 2006; 2) approaches for transitioning between the RIA used in the NHANES between 1988 and 2006 to the liquid chromatography tandem MS (LC-MS/MS) measurement procedure to be used in NHANES 2007 and later; 3) approaches for integrating the recently available standard reference material for vitamin D in human serum (SRM 972) from the National Institute of Standards and Technology (NIST) into the NHANES; 4) questions regarding whether the C-3 epimer of 25-hydroxyvitamin D3 [3-epi-25(OH)D3] should be measured in NHANES 2007 and later; and 5) identification of research and educational needs. The roundtable experts agreed that the NHANES data needed to be adjusted to control for assay fluctuations and offered several options for addressing this issue. The experts suggested that the LC-MS/MS measurement procedure developed by NIST could serve as a higher order reference measurement procedure. They noted the need for a commutability study for the recently released NIST SRM 972 across a range of measurement procedures. They suggested that federal agencies and professional organizations work with manufacturers to improve the quality and comparability of measurement procedures across all laboratories. The experts noted the preliminary nature of the evidence of the 3-epi-25(OH)D3 but felt that it should be measured in 2007 NHANES and later.

Calcium intake and bone mineral density as an example of non-linearity and threshold analysis

“…Areal bone mineral density (BMD) of the femoral neck area was measured using dual energy X-ray absorptiometry [24]. Furthermore, blood samples were taken and serum vitamin D levels examined by radioimmunoassay [49].…”

Analytical methods and performance of the immunoassay methods for determination of vitamin d in comparison to mass spectrometry / Analitičke metode i izvođenje imunometrijskih određivanja vitamina d u poređenju sa masenom spektrometrijom

“…This interference is only problematic for LC-MS/MS methodology, since the mass spectrometers cannot distinguish stereoisomers (35), and can potentially result in overestimation of 25-OHD 3 . None of the main immunoassays in use today are susceptible to 3-epi-25-OHD 3 interference (14). Although the amounts of vitamin D epimer in adult serum are generally small, high concentrations have been reported in some individuals (36).…”

Recent Vitamin D Data from NHANES: Variability, Trends, Deficiency and Sufficiency Rates, and Assay Compatibility Issues

“…Ginde et al [4] [40] reported that there was a change in the DioSorin RIA kits used over 1988-2004 because during the later years a new antibody with improved binding was introduced and detergents were added to a buffer to reduce nonspecific binding. They [40] also reported that to obtain corrected values for 1988-1994, they be multiplied by 0.8429.…”

“…They [40] also reported that to obtain corrected values for 1988-1994, they be multiplied by 0.8429. If that was to be so, reported mean of 30 ng/mL for 1988-1994 will be corrected to 25.2 ng/mL or just about the same as for 2001-2004.…”