SIGNIFICANT SEASONAL VARIATIONS OF 25-OHD BLOOD LEVELS REFLECTING SUN EXPOSURE IN THE SOUTH MORAVIAN REGION OF THE CZECH REPUBLIC

Background:

Vitamin D plays an important role in a number of physiological functions including calcium absorption, bone metabolism, immune function, muscle function and cellular regulation. Numerous clinical studies have shown that vitamin D has significant protective effect against the development of cancer. We studied changes in 25(OH)D serum concentrations in healthy individuals in the spring and autumn to assess difference between late spring and early autumn period in our geographical location.

Materials and Methods:

The serum aliquots were derived from blood of healthy individuals who visited Masaryk Memorial Cancer Institute (MMCI) to receive preventive health check up focused on early cancer detection. This cancer prevention program is avail able at MMCI and is not reimbursed by health insurance system. Out of this cohort, 437 blood samples in March and April and 508 blood samples in September, October were taken in sample tube without anticoagulant. Collected samples were left to coagulate 45 minutes. After centrifugation (1,500 g, 15 ˚C, 20 min) separation serum was stored in short term storage serum repository of bio bank at –20 ˚C. Subsequently, 25(OH)D serum concentrations were measured using Architect i2000sr (Abbott) analyzer within one week.

Results:

We found vast differences in concentrations of 25(OH)D between “spring” and “autumn” group. In the spring group median of 25(OH)D concentration was 42.7 nmol/ l (95% CI 21.9–90.1 nmol/ l). In the autumn group median of 25(OH)D was 70.8 nmol/ l (95% CI 37.0–137.5 nmol/ l).

Conclusion:

We observed fundamental differences in 25(OH)D concentrations between late spring and late summer which is in our latitude due to exposure to sunlight during the summer. This finding may have substantial implications for populational health. However, our data may be slightly biased by the type of a source population that may carry more active lifestyle than the true population average.

This study was funded by European Regional Development Fund and State budget of the Czech Republic (RECAMO: CZ 1.05/ 2.1.00/ 03.0101) and by Ministry of Education, Youth and Sports (BBMRI: LM2010004).