Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Francic,V.
Vitamin D, clinical outcomes and regulation of metabolism
PhD-Studium (Doctor of Philosophy); Humanmedizin; [Dissertation] Medical University of Graz;2019. pp. 102
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- Autor*innen der Med Uni Graz:
- Betreuer*innen:
- Obermayer-Pietsch Barbara
- Pilz Stefan
- Rinner Beate
- Altmetrics:
- Abstract:
- Vitamin D is a pleiotropic steroid hormone and regulates the expression of a wide variety of genes. Vitamin D metabolism is tightly regulated and serum levels show seasonal patterns. Vitamin D deficiency has been linked to skeletal as well as non-skeletal health conditions such as cardiovascular disease. Many aspects of governing the non-skeletal actions of vitamin D and even its metabolism are still poorly understood. We investigated three of these aspects regarding vitamin D catabolism and the usefulness of 24,25-dihydroxyvitamin D3 (24,25(OH)2D3) and the vitamin D metabolite ratio (VMR), regarding the seasonality of a cardiovascular biomarker soluble ST2 (sST2) as well as regarding the effects of vitamin D on non-oxidized PTH. We used the data and samples gathered in the Styrian Vitamin D in Hypertension Trial and the Ludwigshafen Risk and Cardiovascular Health Study to assess our hypotheses. In the first sub-study we found that VMR and 24,25(OH)2D3 increased after vitamin D treatment, although, these parameters can’t be used to predict the changes in 25(OH)D levels after vitamin D treatment. In the second sub-study we found that systemic sST2 levels weren’t affected by vitamin D supplementation and in a separate cohort we also demonstrated that sST2 concentrations didn’t change alongside 25(OH)D concentrations and remained mostly constant without significant fluctuations throughout the whole year. In the third sub-study we observed a reduction in both total PHT (tPTH) and n-oxPTH after vitamin D supplementation and our data indicate that measuring n-oxPTH might be a better alternative to tPTH, at least in the case of patients prone to oxidative stress. In conclusion, although vitamin D RCTs have shown mostly negative results in recent years, we found they can still be useful tools for uncovering promising and potentially clinically important findings as indicated by our findings regarding 24,25(OH)2D3, the VMR, sST2 and n-oxPTH.