Abstract
Within the last several years, frequency of vitamin D testing has multiplied substantially all over the world, since it has been shown to have an important role in many diseases and conditions. Even though liquid chromatography - tandem mass spectrometry (LC-MS/MS) has been identified as “gold standard” method for vitamin D measurement, most laboratories still use immunochemistry methods. Besides analytical problems (hydrophobicity, low circulating concentrations, ability to bind to lipids, albumins and vitamin D binding protein, presence of multiple vitamin D metabolites and variable ratios of 25(OH)D2 and 25(OH)D3 in the blood), vitamin D shows great preanalytical variability, since its concentration is drastically influenced by seasonal changes, exposure to sun, type of clothes or sun block creams. Vitamin D is mostly measured in serum or plasma, but new studies are showing importance of measuring vitamin D in pleural effusions, breast milk, urine, synovial fluid and saliva. Besides the main role in calcium homeostasis and bone metabolism, many studies linked vitamin D deficiency with cancer, cardiovascular diseases, diabetes, fertility and many other conditions. However, even though initial observational studies indicated that supplementation with vitamin D might be beneficial in disease development and progression; first results of well-designed randomized controlled prospective studies did not find differences in frequency of cardiovascular events or invasive cancer between patients taking vitamin D supplementation compared to placebo. In the light of these recent findings, validity of excessive vitamin D testing remains an open question.
Highlights
Prolific scientific activity has always been one of the main missions of the Croatian Society of Medical Biochemistry and Laboratory Medicine (CSMBLM)
One of the longest continuous courses organized under the CSMBLM auspices is the annual symposium, which has been held in Zagreb in September 2019 for the 30th time
One should be aware that these cutoff values are not obtained on the evidence-based principle and most societies and organizations refer to the single point of origin when defining re commended vitamin D concentrations, resulting in a high number of vitamin D deficient individuals [2]
Summary
Prolific scientific activity has always been one of the main missions of the Croatian Society of Medical Biochemistry and Laboratory Medicine (CSMBLM). One should be aware that these cutoff values are not obtained on the evidence-based principle and most societies and organizations refer to the single point of origin when defining re commended vitamin D concentrations, resulting in a high number of vitamin D deficient individuals [2]. One of the largest studies (N = 25,871) did not find differences in the frequency of cardiovascular events or invasive cancer between patients taking vitamin D supplementation compared to placebo [8]. These findings might have long-term effects on the future of vitamin D testing
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