Vitamin D deficiency and thyroid autoantibody fluctuations in patients with Graves' disease - A mere coincidence or a real relationship?

Vitamin D-Related Genes and Thyroid Cancer-A Systematic Review

Vitamin D, formerly known for its role in calcium-phosphorus homeostasis, was shown to exert a broad influence on immunity and on differentiation and proliferation processes in the last few years. In the field of endocrinology, there is proof of the potential role of vitamin D and vitamin D-related genes in the pathogenesis of thyroid cancer-the most prevalent endocrine malignancy. Therefore, the study aimed to systematically review the publications on the association between vitamin D-related gene variants (polymorphisms, mutations, etc.) and thyroid cancer. PubMed, EMBASE, Scopus, and Web of Science electronic databases were searched for relevant studies. A total of ten studies were found that met the inclusion criteria. Six vitamin D-related genes were analyzed (VDR-vitamin D receptor, CYP2R1-cytochrome P450 family 2 subfamily R member 1, CYP24A1-cytochrome P450 family 24 subfamily A member 1, CYP27B1-cytochrome P450 family 27 subfamily B member 1, DHCR7-7-dehydrocholesterol reductase and CUBN-cubilin). Moreover, a meta-analysis was conducted to summarize the data from the studies on VDR polymorphisms (rs2228570/FokI, rs1544410/BsmI, rs7975232/ApaI and rs731236/TaqI). Some associations between thyroid cancer risk (VDR, CYP24A1, DHCR7) or the clinical course of the disease (VDR) and vitamin D-related gene polymorphisms were described in the literature. However, these results seem inconclusive and need validation. A meta-analysis of the five studies of common VDR polymorphisms did not confirm their association with increased susceptibility to differentiated thyroid cancer. Further efforts are necessary to improve our understanding of thyroid cancer pathogenesis and implement targeted therapies for refractory cases.

Vitamin D, Thyroid Hormones and Cardiovascular Risk: Exploring the Components of This Novel Disease Triangle

The role of thyroid hormones (THs) in the cardiovascular (CV) system, through several direct and indirect effects is recognized. Even very small modification in TH levels (as those observed in subclinical hypothyroidism or hyperthyroidism, and low triiodothyronine syndrome) may adversely affect the CV system, whereas thyroid hormones benefit the CV system and improve the prognosis. There is also evidence of vitamin D effects on cardiometabolic disease (e.g., through modulation of endothelial and smooth muscle cell activity, renin-angiotensin-aldosterone system, nitric oxide, oxidative stress, and inflammatory response), as well as an association between vitamin D [25(OH)D] deficiency and autoimmune thyroid diseases or cancer, and a relationship between vitamin D concentration and titers of antibodies and thyroid autoimmunity replacement. Interestingly, experimental data indicate a direct effect of vitamin D on Type 2 deiodinase expression causing subsequential peripheral conversion of T4 into T3. However, the functional links among THs, vitamin D and the cardiovascular system, and clinical effects of coexisting abnormalities in this new troublesome triad, have not yet been reviewed. The main aim of this review is to discuss pathophysiology of this relationship, proposing new mechanistic insights involving vitamin D in the modulation of cardiometabolic disease and thyroid profile.

Evaluation of vitamin D storage in patients with chronic kidney disease: Detection of serum vitamin D metabolites using high performance liquid chromatography-tandem mass spectrometry

BACKGROUND

Vitamin D (VitD) deficiency is extremely common in chronic kidney disease (CKD). However, the current clinical testing of vitamin D is based on the recommended serum 25-hydroxyvitamin D [25(OH)D]. The levels of VitD components in CKD patients are rarely reported. In this study, we tested various VitD components, and used different methods to evaluate the VitD status of CKD patients in vivo.

METHODS

Totally 173 CKD patients and 111 control individuals were enrolled. Serum levels of 25(OH)D₂, 25(OH)D₃, C₃-epimers (C₃-epi) and free 25(OH)D [f-25(OH)D] were measured. The 25(OH)D₂/25(OH)D₃ ratio, C₃-epi/25(OH)D₃ ratio, total 25(OH)D [t-25(OH)D], and bioavailable vitamin D (BAVD) were calculated, respectively.

RESULTS

The ratios of 25(OH)D₂/25(OH)D₃, C₃-epi/25(OH)D₃, and the level of C₃-epi in CKD patients were significantly higher than those in the control group (all P < 0.05). The levels of t-25(OH)D, 25(OH)D₃, C₃-epi, f-25(OH)D and BAVD in patients with CKD stage 5 were significantly lower than those in stages 2, 3, and 4 (all P < 0.05). The calculated VitD storage according to Method 3 [25(OH)D₂/3 + 25(OH)D₃] was only 32.95 %, which was lower than the results of 53.76 % by Method 1 [25(OH)D₂+ 25(OH)D₃+C₃-epi] and 48.56 % by Method 2 [25(OH)D₂/3 + 25(OH)D₃+C₃-epi]. In addition, the VitD results calculated by three methods were positively correlated with f-25(OH)D and BAVD, while C₃-epi levels were also positively correlated with f-25(OH)D and BAVD.

CONCLUSION

Serum levels of t-25(OH)D, 25(OH)D₃, C₃-epi, f-25(OH)D and BAVD in CKD patients gradually decrease with the progression of CKD stages. Though the results of VitD storage in CKD patients evaluated by different methods are different, simultaneous detection of 25(OH)D₂, 25(OH)D₃, C₃-epi and f-25(OH)D levels and fully estimation of their respective biological activities could accurately evaluate the VitD storage in vivo.