scholarly journals Interlaboratory comparison of 25-hydroxyvitamin D assays: Vitamin D Standardization Program (VDSP) Intercomparison Study 2 — Part 2 ligand binding assays — impact of 25-hydroxyvitamin D2 and 24R,25-dihydroxyvitamin D3 on assay performance

2021 ◽  
Author(s):  
Stephen A. Wise ◽  
Johanna E. Camara ◽  
Carolyn Q. Burdette ◽  
Grace Hahm ◽  
Federica Nalin ◽  
...  
Keyword(s):  
Vitamin D ◽  
Ligand Binding ◽  
Interlaboratory Comparison ◽  
Binding Assays ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Assay Performance ◽  
25 Hydroxyvitamin D ◽  
Intercomparison Study

Baseline Assessment of 25-Hydroxyvitamin D Assay Performance: A Vitamin D Standardization Program (VDSP) Interlaboratory Comparison Study

2017 ◽  
Vol 100 (5) ◽  
pp. 1244-1252 ◽  
Author(s):  
Stephen A Wise ◽  
Karen W Phinney ◽  
Susan S-C Tai ◽  
Johanna E Camara ◽  
Gary L Myers ◽  
...  
Keyword(s):  
Vitamin D ◽  
Interlaboratory Comparison ◽  
Performance Criteria ◽  
Hydroxyvitamin D ◽  
Assay Performance ◽  
Target Values ◽  
25 Hydroxyvitamin D ◽  
Lc Tandem Ms ◽  
Individual Donor

Abstract The Vitamin D Standardization Program (VDSP) coordinated an interlaboratory study to assess the comparability of measurements of total 25-hydroxyvitamin D [25(OH)D] in human serum, which is the primary marker of vitamin D status. A set of 50 individual donor samples were analyzed by 15 different laboratoriesrepresenting national nutrition surveys, assay manufacturers, and clinical and/or research laboratories to provide results for total 25(OH)D using both immunoassays (IAs) and LC tandem MS (MS/MS). The resultswere evaluated relative to bias compared with the target values assigned based on a combination of measurements at Ghent University (Belgium) and the U.S. National Institute of Standards and Technology using reference measurement procedures for the determination of 25(OH)D2 and 25(OH)D3. CV and mean bias for each laboratory and assay platform were assessed and compared with previously established VDSP performance criteria, namely CV ≤ 10% and mean bias ≤ 5%. Nearly all LC-MS/MS results achieved VDSP criteria, whereas only 50% of IAs met the criterion for a ≤10% CV and only three of eight IAs achieved the ≤5% bias. These results establish a benchmark for the evaluation of 25(OH)D assay performance and standardization activities in the future.

scholarly journals A Comparison of Free and Total 25-hydroxyvitamin D Levels as Functional Indicators of Bone Health in Healthy Children

2021 ◽  
Vol 5 (Supplement_1) ◽  
pp. A270-A270
Author(s):  
You Joung Heo ◽  
Yun Jeong Lee ◽  
Kyunghoon Lee ◽  
Jae Hyun Kim ◽  
Choong Ho Shin ◽  
...  
Keyword(s):  
Vitamin D ◽  
Bone Health ◽  
Normal Weight ◽  
Healthy Children ◽  
Vitamin D Metabolites ◽  
Dihydroxyvitamin D3 ◽  
Bone Parameters ◽  
Hydroxyvitamin D ◽  
25 Hydroxyvitamin D ◽  
24,25 Dihydroxyvitamin D3

Abstract Abstract Context: The “free hormone” hypothesis suggests that the free 25-hydroxyvitamin D (25OHDFree) level may usefully indicate bone health. Objective: To determine which vitamin D measure is optimally correlated with clinical and bone parameters in healthy children. Design and Participants: A cross-sectional study including 146 healthy children (71 boys, 9.5±1.9 years) at a tertiary medical center. Main Outcome Measures: We used a multiplex liquid chromatography-tandem mass spectrometry-based assay to simultaneously measure vitamin D metabolites. The 25OHDFree level was directly measured (m-25OHDFree) or calculated using genotype-constant or genotype-specific affinity coefficients of vitamin D-binding proteins (con-25OHDFree or spe-25OHDFree). Bone mineral content (BMC) and density (BMD) were assessed via dual-energy X-ray absorptiometry. Results: The concentrations of total 25OHD (25OHDTotal), the three forms of 25OHDFree, and 24,25-dihydroxyvitamin D3 correlated with parathyroid hormone levels (all p<0.01). Serum 25OHDTotal and m-25OHDFree levels reflected age, puberty, season, body mass index (BMI), daylight hours, and vitamin D intake (all p<0.05). The con-25OHDFree level better reflected puberty and daylight hours than did the spe-25OHDFree level (both p<0.01). The association between the 25OHDTotal level and bone parameters varied according to the BMI (interaction p<0.05). In 109 normal-weight children, the con-25OHDFree level correlated with BMC and BMD (both p<0.05), but the 25OHDTotal and 24,25-dihydroxyvitamin D3 levels were associated with BMC (both p<0.05). No association was found in overweight or obese children. Conclusions: In healthy children, total and free 25OHD levels comparably reflected lifestyle factors. In normal-weight children, the con-25OHDFree level reflected BMC and BMD, whereas the 25OHDTotal level was associated with BMC.

Assay of vitamins D2 and D3, and 25-hydroxyvitamins D2 and D3 in human plasma by high-performance liquid chromatography.

1978 ◽  
Vol 24 (2) ◽  
pp. 287-298 ◽  
Author(s):  
G Jones
Keyword(s):  
Vitamin D ◽  
Protein Binding ◽  
High Performance ◽  
High Performance Liquid Chromatographic ◽  
Reversed Phase ◽  
Vitamin D Metabolites ◽  
Binding Assays ◽  
Hydroxyvitamin D ◽  
Chemical Assay ◽  
25 Hydroxyvitamin D

Abstract I describe a new assay that is capable of measuring vitamin D2, vitamin D3, 25-hydroxyvitamin D2, and 25-hydroxyvitamin D3 in 2 ml of plasma or serum. Plasma is extracted by the Bligh and Dyer technique [Can. J. Biochem. Physiol. 37, 911 (1959)], the lipid component is fractionated by two high-performance liquid-chromatographic systems based upon adsorption and reversed-phase chromatography, and each of the four vitamin D metabolites is measured by its absorbance at 254 nm. The method has a sensitivity limit of 0.5 mug/liter of plasma. The identity of metabolite peaks was confirmed by mass spectrometry, ultraviolet absorption spectrophotometry, and rechromatography, and there was good correlation (r=0.84) between plasma 25-hydroxyvitamin D as measured by the present method and by a protein binding assay developed in our laboratory. Mean concentrations of vitamin D and 25-hydroxyvitamin D in normal adults (n=25) in December were 2.2 +/- 1.1 (SD) and 16 +/- 3.9 (SD) mug/liter, respectively. 25-Hyroxyvitamin D2 made up 31% of the total 25-hydroxyvitamin D. Patients receiving pharmacological doses of vitamin D had values for vitamin D and 25-hydroxyvitamin D that were 10- to 100-fold normal. This method provides a rapid, reliable physico-chemical assay that appears to have advantages over existing protein binding assays and can be used to measure circulating vitamin D.

Simultaneous determination of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D in plasma or serum.

1981 ◽  
Vol 27 (10) ◽  
pp. 1757-1760 ◽  
Author(s):  
M J Jongen ◽  
W J van der Vijgh ◽  
H J Willems ◽  
J C Netelenbos ◽  
P Lips
Keyword(s):  
Vitamin D ◽  
Vitamin D Metabolites ◽  
Binding Assays ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
1,25 Dihydroxyvitamin D ◽  
Extraction And Purification ◽  
Chromatographic Procedure ◽  
25 Hydroxyvitamin D ◽  
Liquid Chromatographic

Abstract We describe a simultaneous assay for the principal vitamin D metabolites: 25-hydroxyvitamin D, 24-25-dihydroxyvitamin D, and 1,25-dihydroxyvitamin D. Special attention has been paid to simplification of the extensive extraction and purification procedures used in previously described simultaneous assays. All three metabolites were isolated with a single extraction step, followed by only one gradient liquid-chromatographic procedure. For final quantitation we used competitive protein binding assays, involving readily available binding proteins and commercially purchased tritiated vitamin D metabolites. Concentrations in the plasma of healthy subjects (mean age, 27 years), sampled during December were 51 (SD 17) nmol/L, 4.1 (SD 1.3) nmol/L, and 124 (SD 26) pmol/L for 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D and 1,25-dihydroxyvitamin D, respectively. Intra- and interassay CVs for the three metabolites were 4.4 and 3.9%, 6.7 and 8.0%, and 7.0 and 4.8%, respectively.

1,25-Dihydroxyvitamin D3 downregulates the rat intestinal vitamin D3-25-hydroxylaseCYP27A

2001 ◽  
Vol 281 (2) ◽  
pp. E315-E325 ◽  
Author(s):  
Catherine Theodoropoulos ◽  
Christian Demers ◽  
Ali Mirshahi ◽  
Marielle Gascon-Barré
Keyword(s):  
Vitamin D ◽  
Direct Action ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Dihydroxyvitamin D ◽  
Protein Levels ◽  
25 Hydroxyvitamin D ◽  
Extrahepatic Tissues ◽  
Mrna Half Life

The vitamin D3-25-hydroxylase CYP27A is located predominantly in liver, but its expression is also detected in extrahepatic tissues. Our aim was to evaluate the regulation of CYP27A by vitamin D3 (D3) or its metabolites in rat duodena. Vitamin D-depleted rats were repleted with D3, 25-hydroxyvitamin D (25OHD), or 1,25-dihydroxyvitamin D3[1,25(OH)2D3] or acutely injected 1,25(OH)2D3 to investigate the mechanisms of action of the hormone. All D3 compounds led to a progressive decrease in CYP27A mRNA, with levels after D3 representing 20% of that observed in D depletion. 25OHD decreased CYP27A mRNA by 55%, whereas 1,25(OH)2D3 led to a 40% decrease, which was accompanied by a 31% decrease in CYP27A protein levels and an 89% decrease in enzyme activity. Peak circulating 1,25(OH)2D3 concentrations were, however, the highest in D3-repleted, followed by 25OHD- and 1,25(OH)2D3-repleted animals. 1,25(OH)2D3 resulted in a decrease in both CYP27A mRNA half-life and transcription rate. Our data illustrate that the intestine expresses the D3-25-hydroxylase and that the gene is highly regulated in vivo through a direct action of 1,25(OH)2D3 or through the local production of D3 metabolites.

Expression of the renal 25-hydroxyvitamin D-24-hydroxylase gene: regulation by dietary phosphate

1996 ◽  
Vol 271 (1) ◽  
pp. F203-F208 ◽  
Author(s):  
S. Wu ◽  
J. Finch ◽  
M. Zhong ◽  
E. Slatopolsky ◽  
M. Grieff ◽  
...  
Keyword(s):  
Vitamin D ◽  
Gene Regulation ◽  
Mrna Level ◽  
Catabolic Pathway ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Pi Homeostasis ◽  
1,25 Dihydroxyvitamin D3 ◽  
Dietary Phosphate ◽  
25 Hydroxyvitamin D

1,25-Dihydroxyvitamin D3 [1,25(OH)2D3] plays a key role in phosphate (Pi) homeostasis through its phosphatemic actions on intestine and bone. In turn, dietary Pi restriction increases serum 1,25(OH)2D3 by stimulating its production, but its effect on vitamin D catabolism is less clear. Here we have examined the effects of dietary Pi on the expression of the renal vitamin D-24-hydroxylase (24-OHase), the first enzyme in the catabolic pathway for vitamin D compounds. Rats fed a low Pi (0.02% P) diet showed a fivefold decrease in renal 24-OHase mRNA compared with rats fed a normal Pi (0.67% P) diet. 24-OHase mRNA and 24-OHase activity decreased within 24 h of Pi restriction, reached a minimum by 48 h, and remained low through 14 days. Decreased 24-OHase mRNA was observed with more moderate Pi restriction (0.2% P), but higher Pi (1.2% P) did not increase 24-OHase mRNA over the 0.8% P diet. 24-OHase mRNA correlated well with plasma Pi (r = 0.862, P < 0.001). In conclusion, renal 24-OHase expression is regulated by dietary phosphate at the mRNA level.

scholarly journals Differential effects of phosphate binders on vitamin D metabolism in chronic kidney disease

2020 ◽  
Vol 35 (4) ◽  
pp. 616-623 ◽  
Author(s):  
Charles Ginsberg ◽  
Leila R Zelnick ◽  
Geoffrey A Block ◽  
Glenn M Chertow ◽  
Michel Chonchol ◽  
...  
Keyword(s):  
Chronic Kidney Disease ◽  
Vitamin D ◽  
Calcium Acetate ◽  
Phosphate Binders ◽  
Vitamin D Metabolites ◽  
Vitamin D Metabolism ◽  
Dihydroxyvitamin D3 ◽  
Hydroxyvitamin D ◽  
Sevelamer Carbonate ◽  
25 Hydroxyvitamin D

Abstract Background Phosphate binders are commonly used in the treatment of patients with hyperphosphatemia. While phosphate binders are used to lower phosphate, the effects of specific phosphate binder types on vitamin D metabolism are unknown. Methods We performed a secondary analysis of the Phosphate Normalization Trial in which patients with moderate to advanced chronic kidney disease were randomized to receive either placebo, sevelamer carbonate, lanthanum carbonate or calcium acetate for 9 months. We evaluated changes in serum concentrations of vitamin D metabolites including 24,25-dihydroxyvitamin D3 [24,25(OH)2D3], 1,25-dihydroxyvitamin D3 [1,25(OH)2D3], the ratio of 24,25(OH)2D3 to 25-hydroxyvitamin D [the vitamin D metabolite ratio (VMR)] and the ratio of serum 1,25(OH)2D to 25-hydroxyvitamin D. Results Compared with placebo, randomization to the calcium acetate arm was associated with a 0.6 ng/mL (95% CI 0.2, 1) and 13.5 pg/ng (95% CI 5.5, 21.5) increase in 24,25(OH)2D and VMR, respectively, and a 5.2 pg/mL (95% CI 1.1, 9.4) reduction in 1,25(OH)2D. Randomization to sevelamer carbonate was associated with a 0.5 ng/mL (95% CI −0.9, −0.1) and 11.8 pg/ng (95% CI −20, −3.5) reduction in 24,25(OH)2D3 and VMR, respectively. There was no association of the sevelamer arm with the change in 1,25(OH)2D3, and randomization to lanthanum carbonate was not associated with a change in any of the vitamin D metabolites. Conclusion Administration of different phosphate binders to patients with moderate to severe CKD results in unique changes in vitamin D metabolism.

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