Metrological approaches to organic chemical purity: primary reference materials for vitamin D metabolites

2015 ◽  
Vol 407 (28) ◽  
pp. 8557-8569 ◽  
Author(s):  
Michael A. Nelson ◽  
Mary Bedner ◽  
Brian E. Lang ◽  
Blaza Toman ◽  
Katrice A. Lippa
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.


Author(s):  
Jan Mieszkowski ◽  
Andrzej Kochanowicz ◽  
Elżbieta Piskorska ◽  
Bartłomiej Niespodziński ◽  
Joanna Siódmiak ◽  
...  

Abstract Purpose/introduction To compare serum levels of bone turnover markers in athletes and non-athletes, and to evaluate the relationship between serum levels of vitamin D metabolites and exercise-induced changes in biomarker levels. Methods Sixteen elite male artistic gymnasts (EG; 21.4 ± 0.8 years-old) and 16 physically active men (the control group, PAM; 20.9 ± 1.2 years-old) performed lower and upper body 30-s Wingate anaerobic tests (LBWT and UBWT, respectively). For biomarker analysis, blood samples were collected before, and 5 and 30 min after exercise. Samples for vitamin D levels were collected before exercise. N-terminal propeptide of type I collagen (PINP) was analysed as a marker of bone formation. C-terminal telopeptide of type I collagen (CTX) was analysed as a marker of bone resorption. Results UBWT fitness readings were better in the EG group than in the PAM group, with no difference in LBWT readings between the groups. UBWT mean power was 8.8% higher in subjects with 25(OH)D3 levels over 22.50 ng/ml and in those with 24,25(OH)2D3 levels over 1.27 ng/ml. Serum CTX levels increased after both tests in the PAM group, with no change in the EG group. PINP levels did not change in either group; however, in PAM subjects with 25(OH)D3 levels above the median, they were higher than those in EG subjects. Conclusion Vitamin D metabolites affect the anaerobic performance and bone turnover markers at rest and after exercise. Further, adaptation to physical activity modulates the effect of anaerobic exercise on bone metabolism markers.


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