scholarly journals Environmental and genetic determinants of two vitamin D metabolites in healthy Australian children

Author(s):  
Abdulhadi Bima ◽  
Angela Pezic ◽  
Cong Sun ◽  
Fergus J. Cameron ◽  
Christine Rodda ◽  
...  

AbstractBackground:Vitamin D deficiency has been associated with adverse health outcomes. We examined genetic and environmental determinants of serum 25(OH)DMethods:The study sample consisted of 322 healthy Australian children (predominantly Caucasians) who provided a venous blood sample. A parental interview was conducted and skin phototype and anthropometry measures were assessed. Concentrations of 25(OH)DResults:Deseasonalised log 25(OH)DConclusions:Environmental factors and genetic factors contributed to both vitamin D metabolite concentrations. The intriguing finding that the higher ambient UVR contributed to higher 1,25(OH)

2016 ◽  
Vol 62 (1) ◽  
pp. 179-187 ◽  
Author(s):  
Clark M Henderson ◽  
Pamela L Lutsey ◽  
Jeffrey R Misialek ◽  
Thomas J Laha ◽  
Elizabeth Selvin ◽  
...  

Abstract BACKGROUND Vitamin D deficiency is associated with poor bone health and other adverse health outcomes; however, the associations are greatly attenuated in black vs white individuals. One possible explanation for this attenuation is different concentrations of bioavailable vitamin D metabolites in plasma, which are estimated with equations that include the total concentration of vitamin D binding globulin (VDBG) and haplotype-specific dissociation constants. METHODS We developed a method to quantify VDBG with LC-MS/MS that could also identify the haplotypes/isoforms of VDBG present. We validated the method according to recent recommendations for publications of biomarker studies. We determined serum VDBG concentrations in samples from the Atherosclerosis Risk in Communities cohort and compared the results with a widely used monoclonal immunoassay. RESULTS With 10 μL of serum or plasma, the lower limit of quantification for the assay (<20% CV) was 71 μg/mL. The assay was linear from 62 to 434 μg/mL, with total imprecision of 7.3–9.0% CV at approximately 250 μg/mL. Significant hemolysis interfered with quantification. The identification of isoforms was 97% concordant with genotyping (κ coefficient). Method comparison with immunoassay revealed significant isoform-specific effects in the immunoassay. Mean concentrations (SD) of VDBG by mass spectrometry were similar in whites and blacks [262 (25) vs 266 (35) μg/mL, respectively; P = 0.43]. CONCLUSIONS Validated mass spectrometric methods for the quantification of proteins in human samples can provide additional information beyond immunoassay. Counter to prior observations by immunoassay, VDBG concentrations did not vary by race.


Biomolecules ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1288
Author(s):  
Sieglinde Zelzer ◽  
Andreas Meinitzer ◽  
Markus Herrmann ◽  
Walter Goessler ◽  
Dietmar Enko

The brain’s supply with vitamin D is poorly understood. Therefore, the present study aimed to determine 25-hydroxy vitamin D3 (25(OH)D) and 24,25-dihydroxy vitamin D (24,25(OH)2D3) in serum and cerebrospinal fluid (CSF) from individuals with intact and disturbed brain-CSF-barrier (BCB) function. In 292 pairs of serum and CSF samples the vitamin D metabolites were measured with liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS). CSF/serum ratios (QALB, Q25(OH)D, Q24,25(OH)2D3) were calculated. Median (IQR) serum concentrations of 25(OH)D and 24,25(OH)2D3 were 63.8 (43.4–83.9) nmol/L and 4.2 (2.2–6.2) nmol/L. The CSF concentrations of both metabolites accounted for 3.7 and 3.3% of the respective serum concentrations. Serum 25(OH)D correlated inversely with Q25(OH)D and Q24,25(OH)2D3 implying a more efficient transport of both metabolites across the BCB when the serum concentration of 25(OH)D is low. In patients with BCB dysfunction, the CSF concentrations and the CSF/serum ratios of both vitamin D metabolites were higher than in individuals with intact BCB. The CSF concentrations of 25(OH)D and 24,25(OH)2D3 depend on BCB function and the respective serum concentrations of both metabolites. Higher vitamin D metabolite concentrations in CSF of patients with impaired BCB function may be due to passive diffusion across the BCB.


Diabetes ◽  
2019 ◽  
Vol 68 (Supplement 1) ◽  
pp. 2223-PUB
Author(s):  
STEPHEN ATKIN ◽  
ALEXANDRA E. BUTLER

1982 ◽  
Vol 42 (6) ◽  
pp. 487-491 ◽  
Author(s):  
Claus Christiansen ◽  
Merete Sanvig Christensen ◽  
Peter McNair ◽  
Britta Nielsen ◽  
Steen Madsbad

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Oleg Tsuprykov ◽  
Saban Elitok ◽  
Claudia Buse ◽  
Chang Chu ◽  
Bernhard Karl Krämer ◽  
...  

Abstract25-Hydroxyvitamin D (25OHD) and 1,25-dihydroxyvitamin D (1,25(OH)2D) need to be bound to carrier proteins to be transported to their target cells. The majority of either 25OHD or 1,25(OH)2D is bound to vitamin D-binding protein (DBP), a smaller fraction is bound to albumin and only very small amounts of 25OHD or 1,25(OH)2D are free. Albumin-bound 25OHD or 1,25(OH)2D is relatively easily available after dissociation from albumin. Thus, the sum of free and albumin-bound forms is called bioavailable 25OHD and bioavailable 1,25(OH)2D. Total 25OHD and 1,25(OH)2D are defined as the sum of free, albumin-bound and DBP-bound 25OHD and 1,25(OH)2D, respectively. This cross-sectional study in 427 pregnant women compared the correlation of the six vitamin D compounds with biomarkers of bone health, lipid metabolism, kidney function, endocrine parameters, and group B water-soluble vitamins. Among the 25OHD metabolites analysed, total 1,25(OH)2D showed clearly the best correlation with calcium, bone-specific alkaline phosphatase, adiponectin, LDL, HDL, urea, thyroxine, and group B water-soluble vitamins. When comparing the three 25OHD metabolites, both free 25OHD and bioavailable 25OHD showed overall good correlations with calcium, bone-specific alkaline phosphatase, adiponectin, LDL, HDL, urea, thyroxine, triiodothyronine, and group B water-soluble vitamins, The correlations of 1,25(OH)2D and 25OHD metabolites went always in opposite directions. Only PTH correlates always inversely with all six vitamin D compounds. In conclusion, free 25(OH)D and bioavailable 25(OH)D are more precise determinants of the vitamin D status than total 25(OH)D in normal pregnancy, whereas total 1,25(OH)2D is superior to free and bioavailable 1,25(OH)2D. Except for PTH, correlations of 25(OH)D and 1,25(OH)2D metabolites with typical clinical chemistry readouts go in opposite directions.


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