20.500.12556/RUL-162184 Seasonal variation of total and bioavailable 25-hydroxyvitamin D [25(OH)D] in the healthy adult Slovenian population Objective: The aim of our study was to compare the total 25(OH)D fraction, the bioavailable vitamin fraction, and the free vitamin D fraction in spring and fall in a group of healthy individuals. Methods: In our study, we collected blood samples from healthy participants at the end of both summer and winter, and measured serum levels of albumin, DBP, and 25(OH)D. Utilizing these data, we calculated the percentage of free and bioavailable vitamin D. Our cohort comprised 87 participants, with a maleto- female ratio of 14:73, aged 35.95 ± 12.55 years, ranging from 19 to 70 years. We employed the chemiluminescence method to determine the vitamin 25(OH)D levels, the ELISA method was utilized to determine DBP levels, the albumin BCP Assay was performed using the ADVIA biochemical analyzer (Siemens) and an online calculator was used to determine the free and bioavailable 25(OH)D levels. Results: Our findings indicate significantly lower 25(OH)D levels in winter (44.13 ± 17.82 nmol/L) compared to summer (74.97 ± 22.75 nmol/L; p < 0.001). For vitamin D binding protein there was no significant difference from summer (236.2 ± 164.39 mg/L) to winter (239.86 ± 141.9 mg/L; p = 0.77), albumin levels were significantly higher in summer (49.37 ± 4.15 g/L vs. 47.97 ± 3.91 g/L, p = 0.01), but the magnitude of the change may not be large enough to be solely responsible for the stability of vitamin D levels throughout the year. In the winter season a significantly lower calculated bioavailable 25(OH)D vitamin (7.45 ± 5.66 nmol/L against 13.11 ± 8.27 nmol/L; p < 0.001) was observed, and the free fraction also showed a significant decrease (17.3 ± 12.9 pmol/L versus 29.7 ± 19.1 pmol/L; p < 0.0001). We observed a moderately positive correlation between 25(OH)D and bioavailable percentage in winter (r = 0.680; p < 0.001), in contrast with a lower positive association in summer (r = 0.343; p < 0.001). Conclusion: Our data suggest a positive correlation between total and bioavailable 25(OH)D levels. In addition to the statistically significant variation in 25(OH)D between the two observation periods, there was an additional variation in the free vitamin D percentage. The summertime synthesis of vitamin D in the skin could contribute directly to the free fraction of vitamin D. Standardizing the measurement of free 25(OH)D and clinical studies is necessary to establish reference values before these methods can be implemented in clinical practice. body mass index ultraviolet D3 cholecalciferol D2 ergocalciferol total 25(OH)D 25-hydroxycholecalciferol calcifediol calcidiol 25-hydroxyvitamin 1 25-(OH)D 1 25-dihydroxyvitamin D vitamin D binding protein Odds ratio indeks telesne mase ultravijolično D3 holekalciferol D2 ergokalciferol skupaj 25(OH)D 25-hidroksiholekalciferol kalcifediol kalcidiol 25-hidroksivitamin 1 25-(OH)D 1 25-dihidroksivitamin D protein ki veže vitamin D razmerje kvot vitamin D true false true Angleški jezik Slovenski jezik Članek v reviji 2024-09-19 12:43:34 2024-09-19 12:43:40 2024-09-23 03:34:52 0000-00-00 00:00:00 2024 0 0 13 str. Vol. 71 2024 0000-00-00 Zaloznikova Objavljeno NiDoloceno 0000-00-00 0000-00-00 0000-00-00 577.161 1734-154X 10.3389/abp.2024.13108 207062787 abp-71-13108_(1).pdf abp-71-13108_(1).pdf 1 10EE33943F467A5892CD7036CBF51A95 60e1105871f2aca5ac64ad95bc3bcb8a08d1c3eb92e453d12d4347028b25dea7 a09b72ef-7674-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=191360 https://www.frontierspartnerships.org/journals/acta-biochimica-polonica/articles/10.3389/abp.2024.13108/full 1 edfc3c6b-7673-11ef-b232-0050569b8976 https://repozitorij.uni-lj.si/Dokument.php?lang=slv&id=191359 Fakulteta za farmacijo Zdravstvena fakulteta Biotehniška fakulteta 0 0 0