Vitamin D and Kidney Diseases: A Narrative Review

The potential role of vitamin D binding protein in kidney disease: a comprehensive review

Chronic kidney disease (CKD) is a growing health concern with a complex etiological landscape. Among the numerous factors implicated, vitamin D binding protein (VDBP) has emerged as a focal point of scientific studies because of its critical role in vitamin D metabolism and immune modulation. The relationship between VDBP and CKD reveals a complex web of molecular and biochemical details that have great potential for improving diagnostic understanding and treatment strategies for CKD. This review summarizes the multifaceted roles of VDBP, including its molecular dynamics, interactions with vitamin D, and subsequent implications for kidney function. The main focus of the discussion is how VDBP affects bone mineral homeostasis, highlighted by the dysregulation of calcium and phosphorus metabolism, which is a part of the pathophysiology of CKD. The discussion also touches on the immunomodulatory scope of VDBP and how it may reduce the chronic inflammatory environment that accompanies CKD. The diagnostic potential of VDBP as a biomarker for CKD has been rigorously examined, highlighting its capacity to improve early detection and prognostic assessment. Modification of VDBP activity has the potential to slow the course of CKD and improve patient outcomes. Furthermore, a detailed examination of the genetic polymorphisms of VDBP and their implications for CKD susceptibility and treatment responsiveness provides a perspective for personalized medical methods. Prospects for the future depend on the expansion of studies that try to understand the molecular mechanisms underlying the VDBP-CKD interaction, in addition to clinical trials that evaluate the effectiveness of VDBP-focused treatment approaches.

Mini review: A reevaluation of nutritional vitamin D in the treatment of chronic kidney disease

Chronic kidney disease-mineral and bone disorder is a syndrome of mineral and bone metabolism abnormalities caused by chronic kidney disease. Osteoporosis is a systemic metabolic bone disease characterized by low bone mass, disruption of bone microstructure, increased brittleness, and a higher propensity for fractures. Both of these conditions significantly affect bone metabolism and substantially increase the risk of fractures. Nutritional vitamin D is an essential trace element in the human body and an important fat-soluble vitamin. One crucial physiological role of nutritional vitamin D is to achieve mineral-bone metabolism balance by regulating calcium homeostasis. This review summarized the metabolism of vitamin in normal population and its specificity in chronic kidney disease. Over the years, the understanding and application of vitamin D in patients with chronic renal failure is changing. As people pay more attention to hypercalcemia, vascular calcification, osteoporosis, nutritional vitamin D has come into people's attention again. More and more studies are discussing how to prescribe vitamin D supplementation in hemodialysis patients.

Bi-directional and multivariate mendelian randomization analysis of the relationship between circulating 25-hydroxyvitamin D concentration and obstructive sleep apnea

Background

25-hydroxyvitamin D [25(OH)D] deficiency in patients with Obstructive Sleep Apnea (OSA) has long been noted, but identifying the exact causal relationship remains hard. Investigation of the causality between 25(OH)D deficiency and OSA would help facilitate disease prevention.

Methods

We conducted a two-sample bi-directional Mendelian randomization (MR) study. For forward analysis, 237 newly identified genetic variants are used as proxies for 25(OH)D to estimate the unconfounded effect on OSA among 16,761 OSA cases and 201,194 controls of European ancestry. Reverse analysis was performed to detect the causal impact of OSA on 25(OH)D levels. The inverse variance weighted (IVW) method was used as the primary analysis. Sensitivity analysis was performed to evaluate the robustness of our results. Multivariate MR analysis was conducted to evaluate the direct link between 25(OH)D and OSA after accounting for body mass index (BMI).

Results

IVW indicated that OSA causally associated with a lower level of 25(OH)D ((β = -0.03, 95% CI = -0.06 ~ -0.007, P = 0.01). No evidence of the causal link from 25(OH)D to OSA was detected (OR = 0.99, 95% CI = 0.88 ~ 1.12, P = 0.85). Sensitivity analysis suggested the MR estimates were not biased. Multivariate MR analysis indicated the effect of OSA on 25(OH)D vanished upon accounting for BMI (β = -0.011, 95% CI = -0.028 ~ 0.007, P = 0.23).

Conclusion

This MR study provided evidence that OSA was causally associated with a lower level of 25(OH)D, which might be driven by BMI. Obesity management should be enhanced in patients with OSA to prevent 25(OH)D deficiency.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-02172-y.