Prevalence and prognostic implications of vitamin D deficiency in chronic kidney disease

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.

Association of Vitamin D Deficiency and Insufficiency with Pathology in Hospitalized Patients

Vitamin D deficiency is one of the most common medical conditions, with approximately one billion people having low vitamin D levels. Vitamin D is associated with a pleiotropic effect (immunomodulatory, anti-inflammatory and antiviral), which can be essential for a better immune response. The aim of this research was to evaluate the prevalence of vitamin D deficiency/insufficiency in hospitalized patients focusing on demographic parameters as well as assessing the possibility of its associations with different comorbidities. Of 11,182 Romanian patients evaluated in the study over 2 years, 28.83% had vitamin D deficiency, 32.11% insufficiency and 39.05% had optimal vitamin D levels. The vitamin D deficiency was associated with cardiovascular disorders, malignancies, dysmetabolic disorders and SARS-CoV2 infection, older age and the male sex. Vitamin D deficiency was prevalent and showed pathology association, while insufficiency of vitamin D (20-30 ng/mL) had lower statistical relevance and represents a grey zone in vitamin D status. Guidelines and recommendations are necessary for homogeneity of the monitoring and management of inadequately vitamin D status in the risk categories.

24,25-Dihydroxy Vitamin D and Vitamin D Metabolite Ratio as Biomarkers of Vitamin D in Chronic Kidney Disease

The appropriate management of vitamin D deficiency and hyperparathyroidism is essential to prevent metabolic bone disorder (MBD) and cardiovascular diseases in chronic kidney disease (CKD). Recently, the 24,25-dihydroxyvitamin D [24,25(OH)₂D] and vitamin D metabolite ratio (VMR), i.e., the ratio of 24,25(OH)₂D to 25-hydroxyvitamin D [25(OH)D], have emerged as biomarkers of vitamin D level. We analyzed the usefulness of vitamin D biomarkers for the evaluation of MBD in patients with CKD. We analyzed blood and urine samples from 208 outpatients with CKD stage G2-G5. 25(OH)D showed a poor correlation with the estimated glomerular filtration rate (eGFR). Conversely, the 24,25(OH)₂D level and VMR were significantly correlated with eGFR and the intact parathyroid hormone level. In conclusion, 24,25(OH)₂D and VMR have the potential to be vitamin D biomarkers for the detection of MBD in CKD patients.

25-Hydroxyvitamin-D deficiency in chronic kidney disease stages III, IV, and V in South Asian population: a retrospective cohort

Objective

Vitamin D deficiency in Chronic Kidney Disease is a known fact, but the data regarding the prevalence and extent of vitamin D deficiency in different stages of Chronic Kidney Disease is scarce. This leads to a delay in addressing this issue. We conducted this study to assess vitamin-D deficiency in different stages of Chronic Kidney Disease to improve the evidence available to Physicians and Nephrologists which can help them better address this common finding in Chronic Kidney Disease.

Methods

This retrospective study from a tertiary care hospital in Karachi, Pakistan, included adult Chronic Kidney Disease patients who had their serum 25 Hydroxy vitamin D levels done. The patients were classified according to stages of Chronic Kidney Disease using Estimated Glomerular Filtration Rate values. Appropriate statistical tests were performed to find a correlation between the severity of vitamin D deficiency in different stages of Chronic Kidney Disease with a statistically significant p value of <0.05 and a 95% confidence interval.

Results

In total, 148 patients were included in the study. All patients had serum 25 Hydroxy vitamin D levels less than 30 ng/ml. The severity of vitamin D deficiency was observed to increase progressively from stage 3A Chronic Kidney Disease through stage 5. Vitamin D levels in Chronic Kidney Disease stage 3 were significantly greater than in Chronic Kidney Disease stages 4 and 5 (p value < 0.001), and stage 5 patients had the lowest vitamin D levels in our study. Similar, statistically significant findings were observed for serum phosphate levels, too, with stage 5 Chronic Kidney Disease patients having a greater serum phosphate concentration than stages 3A and 3B (p value = 0.002, 0.006).

Conclusion

All Chronic Kidney Disease patients in our study either had vitamin D insufficiency or deficiency. In addition, we observed a significant decrease in vitamin D levels from Chronic Kidney Disease stage 3 to stage 5. Greater serum phosphate levels were detected in stage 5 compared to stages 3A and 3B.

Co-occurrence of chronic kidney disease and glaucoma: Epidemiology and etiological mechanisms

As the histology, physiology, and pathophysiology of eyes and kidneys show substantial overlap, it has been suggested that eye and kidney diseases, such as glaucoma and chronic kidney disease (CKD), may be closely interlinked. We review the relationship between CKD and various subtypes of glaucoma, including primary open-angle glaucoma, primary angle- closure glaucoma, normal tension glaucoma, pseudoexfoliation syndrome, and several glaucoma endophenotypes. We also discuss the underlying pathogenic mechanisms and common risk factors for CKD and glaucoma, including atherosclerosis, the renin-angiotensin system, genes and genetic polymorphisms, vitamin D deficiency, and erythropoietin. The prevalence of glaucoma appears elevated in CKD patients, and vice versa, and the literature points to many intriguing associations; however, the associations are not always confirmed, and sometimes apparently opposite observations are reported. Glaucoma and CKD are complex diseases, and their mutual influence is only partially understood.

Characteristics and complications of fracture in older adults with chronic kidney disease: a cross-sectional study

Background

The aim of this study was to analyze the clinical characteristics of older fracture patients with chronic kidney disease (CKD) and to determine the risk factors of perioperative cardiovascular complications.

Methods

We retrospectively reviewed clinical data of older fracture patients with CKD admitted to the Third Hospital of Hebei Medical University from January 2016 to October 2021. The data we collected included baseline characteristics and complications. We finally determined the risk factors of perioperative cardiovascular complications by using logistic regression.

Results

We ended up enrolling 224 patients, and there were 91 (40.6%) males and 133 (59.4%) females, with a median age of 79 years. 80–84 years old was the age group with high incidence of fracture. The majority of fracture occurred indoors (130 cases, 58.0%) and morning (98 cases, 43.8%). Hip fracture was most common (183 cases, 81.7%), of which femoral neck fracture (101 cases, 45.0%) was the most prevalent. The most common comorbid condition was hypertension (171 cases, 76.3%), and anemia was the most common complication (148 cases, 66.1%). Age ≥ 80 years (OR = 2.023, 95% CI 1.110–3.688), previously combined with cardiovascular calcification (OR = 1.901, 95% CI 1.047–3.451) and admission hemoglobin level < 100 g/L (OR = 3.191, 95% CI 1.744–5.838) were independent risk factors of perioperative cardiovascular disease (CVD).

Conclusion

It was especially necessary to enhance fracture prevention for CKD. Patients whose age older than 80, hemoglobin less than 100 g/L on admission and have previous cardiovascular calcification are more likely to develop perioperative CVD. Such patients require reasonable decisions during the perioperative period to avoid the occurrence of CVD.

Air, Land, and Sea: Gene-Environment Interaction in Chronic Disease

Each of us reflects a unique convergence of DNA and the environment. Over the past 2 decades, huge biobanks linked to electronic medical records have positioned the clinical and scientific communities to understand the complex genetic architecture underlying many common diseases. Although these efforts are producing increasingly accurate gene-based risk prediction algorithms for use in routine clinical care, the algorithms often fail to include environmental factors. This review explores the concept of heritability (genetic vs nongenetic determinants of disease), with emphasis on the role of environmental factors as risk determinants for common complex diseases influenced by air and water quality. Efforts to define patient exposure to specific toxicants in practice-based data sets will deepen our understanding of diseases with low heritability, and improved land management practices will reduce the burden of disease.

Effects of vitamin D-related gene polymorphisms on attempted suicide

OBJECTIVE

Emerging evidence suggests that vitamin D might protect from attempted suicide. The study aimed to investigate the associations between single-nucleotide polymorphisms (SNPs) related to vitamin D levels identified in a large genome-wide association study and attempted suicide in rural China.

METHODS

This 1:1 matched case-control study included altogether 510 suicide attempters and 510 community controls. Genotypes of four target SNPs (DHCR7-rs12785878, CYP2R1-rs10741657, GC-rs2282679, and CYP24A1-rs6013897) were determined, and a genetic risk score (GRS) was constructed to evaluate the combined effect of them. Demographic and psychological information was acquired through face-to-face interviews.

RESULTS

The A allele of CYP24A1-rs6013897 was significantly associated with attempted suicide (OR = 1.27, 95% CI, 1.03-1.58, P = 0.029), even after adjusting for demographic and psychological confounders (adjusted OR = 1.53, 95% CI, 1.01-2.30, P = 0.043). The GRS analyses revealed a significantly higher risk of attempted suicide with a greater number of low vitamin D alleles (adjusted OR = 1.33, 95% CI, 1.13-1.58, P < 0.001). Subgroup analyses stratified by sex indicated that the genetic associations were only significant among males with adjusted ORs of 3.77 (95% CI, 1.56-9.10) for the A allele of rs6013897 and 2.04 (95% CI, 1.32-3.17) for GRS.

CONCLUSIONS

Our findings identity CYP24A1-rs6013897 as a potential biomarker for attempted suicide and indicate that a genetic predisposition to lower vitamin D levels may contribute to attempted suicide. It suggests the possibility that vitamin D may have the preventive potential for attempted suicide.

The weak correlation between serum vitamin levels and chronic kidney disease in hospitalized patients: a cross-sectional study

Background

Chronic kidney disease (CKD) has become a global public health problem. Accumulating evidence suggested that vitamins play important roles in the progression of CKD.

Methods

A cross-sectional study was conducted to investigate the vitamin status of patients with CKD at stage 1–5. The serum concentrations of 9 vitamins, vitamin A, B1, B2, B6, B9, B12, C, D, and E were measured by electroanalytical method with a Multi-Vitamin Analyzer. Pearson correlation and multiple linear regression between serum level of vitamins were analyzed.

Results

The median levels of vitamin A, B1, B2, B6, B9, B12, C and E were within the reference ranges or on the borderline. Vitamin D deficiency was found in all patients. Weak correlation was found between vitamin A or vitamin D and estimated glomerular filtration rate (eGFR). The Pearson correlation coefficient were − 0.21766 and 0.19752, respectively. Hypertension, diabetes mellitus, and atherosclerosis were the major comorbidities.

Conclusions

For the first time, the serum levels of 9 vitamins were measured simultaneously in patients with CKD at different stages. Vitamin D deficiency was found in all patients. Weak correlation between vitamin A or vitamin D and eGFR was found.

Correcting anemia and native vitamin D supplementation in kidney transplant recipients: a multicenter, 2 × 2 factorial, open-label, randomized clinical trial

Anemia and vitamin D deficiency are associated with allograft failure, and hence, are potential therapeutic targets among kidney transplant recipients (KTRs). We conducted a multicenter, two-by-two factorial, open-label, randomized clinical trial to examine the effects of anemia correction and vitamin D supplementation on 2-year change in eGFR among KTRs (CANDLE-KIT). We enrolled 153 patients with anemia and >1-year history of transplantation across 23 facilities in Japan, and randomly assigned them to either a high or low hemoglobin target (>12.5 vs. <10.5 g/dl) and to either cholecalciferol 1000 IU/day or control. This trial was terminated early based on the planned interim intention-to-treat analyses (α = 0.034). Among 125 patients who completed the study, 2-year decline in eGFR was smaller in the high vs. low hemoglobin group (i.e., -1.6 ± 4.5 vs. -4.0 ± 6.9 ml/min/1.73 m² ; P = 0.021), but did not differ between the cholecalciferol and control groups. These findings were supported by the fully adjusted mixed effects model evaluating the rate of eGFR decline among all 153 participants. There were no significant between-group differences in all-cause death or the renal composite outcome in either arm. In conclusion, aggressive anemia correction showed a potential to preserve allograft kidney function.

Association between vitamin D deficiency and exercise capacity in patients with CKD, a cross-sectional analysis

BACKGROUND

Evidence is growing for a role of vitamin D in regulating skeletal muscle mass, strength and functional capacity. Given the role the kidneys play in activating total vitamin D, and the high prevalence of vitamin D deficiency in Chronic Kidney Disease (CKD), it is possible that deficiency contributes to the low levels of physical function and muscle mass in these patients.

METHODS

This is a secondary cross-sectional analysis of previously published interventional study, with in vitro follow up work. 34 CKD patients at stages G3b-5 (eGFR 25.5 ± 8.3 mL/min/1.73m2; age 61 ± 12 years) were recruited, with a sub-group (n = 20) also donating a muscle biopsy. Vitamin D and associated metabolites were analysed in plasma by liquid chromatography tandem-mass spectroscopy and correlated to a range of physiological tests of muscle size, function, exercise capacity and body composition. The effects of 1α,25(OH)2D3 supplementation on myogenesis and myotube size was investigated in primary skeletal muscle cells from vitamin D deficient donors.

RESULTS

In vivo, there was no association between total or active vitamin D and muscle size or strength, but a significant correlation with V̇O_2Peak was seen with total vitamin D (25OHD). in vitro, 1α,25(OH)₂D3 supplementation reduced IL-6 mRNA expression, but had no effect upon proliferation, differentiation or myotube diameter.

CONCLUSIONS

Vitamin D deficiency is not a prominent factor driving the loss of muscle mass in CKD, but may play a role in reduced exercise capacity.

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.

The Interplay Between Nutrition, Metabolic, and Endocrine Disorders in Chronic Kidney Disease

The kidneys are responsible for maintaining our bodies' homeostasis through excretion, biodegradation, and synthesis of different hormones. Therefore, a decline in renal function often results in significant derangements in hormone levels. The most common metabolic and endocrine abnormalities seen in patients with chronic kidney disease include deficiencies in erythropoietin, calcitriol, triiodothyronine, testosterone, and estrogen. In addition, accumulation of hormones such as adiponectin, leptin, triglycerides, and prolactin also is seen. Subsequently, this can lead to the development of a wide range of clinical consequences including but not limited to anemia, hyperparathyroidism, insulin resistance, anorexia-cachexia, infertility, bone disorders, and cardiovascular diseases. These disorders can negatively affect the prognosis and quality of life of patients with chronic kidney disease, and, thus, early diagnosis, nutritional intervention, and pharmacologic treatment is imperative.

Association between vitamin D levels and mortality in hemodialysis patients: a cohort study

Introduction: Low vitamin D levels are associated with mortality in hemodialysis (HD) patients; however, the serum vitamin D thresholds are unclear. This study aimed to identify the vitamin D level below which mortality increases in HD patients.Methods: A cohort of HD patients enrolled from January 2014 to January 2017 was evaluated. The variables were analyzed according to the season, namely, summer, winter, and annual average, mortality was the primary outcome. The patients were assigned to vitamin D quintiles, and multivariate Cox regression analysis adjusted for age, ethnicity, gender, body mass index (BMI), inhibitors of the renin-angiotensin system, statin, calcitriol, and antiplatelet drugs use, hemodialysis vintage, hypertension, diabetes mellitus, atherosclerotic disease, and C-reactive protein was performed.Results: There were studied 306 patients. Vitamin D levels of 18.0-23.6 ng/mL (hazard ratio [HR] = 4.30; 95% confidence interval [CI] 1.60-11.54, p = 0.004) and <18.0 ng/mL (HR = 3.83; 95% CI: 1.42-10.35, p = 0.008) in summer and vitamin D levels of 21.5-27.1 ng/mL (HR = 3.70; 95% CI: 1.50-9.11, p = 0.004) and ≤17.5 ng/mL (HR = 2.84; 95% CI: 1.13-7.13, p = 0.026) in winter were associated with mortality. The average annual values of vitamin D associated with all-cause mortality were <17.7 ng/dL (adjusted HR = 4.25, 95% CI: 1.57-11.48, p = 0.004), and between >17.7 ng/dL and ≤23.1 ng/dL (adjusted HR = 3.91, 95% CI: 1.47-10.42, p = 0.006).Conclusions: Annual average vitamin D levels <23.1 ng/mL were associated with higher all-cause mortality, regardless of the confounding variables evaluated.

Effect of cholecalciferol on serum hepcidin and parameters of anaemia and CKD-MBD among haemodialysis patients: a randomized clinical trial

In this multicentre double-blind randomized clinical trial, we investigated the effects of oral cholecalciferol supplementation on serum hepcidin and parameters related to anaemia and CKD-MBD among haemodialysis patients. Participants were assigned in a 2:2:1:1 ratio to either (1) thrice-weekly 3,000-IU cholecalciferol, (2) once-monthly cholecalciferol (equivalent to 9,000 IU/week), (3) thrice-weekly placebo, or (4) once-monthly placebo. We also examined the effect modifications by selected single nucleotide polymorphisms in vitamin D-related genes. Out of 96 participants, 94 were available at Month 3, and 88 completed the 6-month study. After adjustment for baseline values, serum hepcidin levels were higher at Day 3 in the combined cholecalciferol (vs. placebo) group, but were lower at Month 6 with increased erythropoietin resistance. Cholecalciferol increased serum 1,25(OH)₂D levels, resulting in a greater proportion of patients who reduced the dose of active vitamin D at Month 6 (31% vs. 10% in the placebo group). Cholecalciferol also suppressed intact PTH only among patients with severe vitamin D deficiency. In conclusion, cholecalciferol supplementation increases serum hepcidin-25 levels in the short term and may increase erythropoietin resistance in the long term among haemodialysis patients. Both thrice-weekly and once-monthly supplementation effectively increases serum 1,25(OH)₂D levels, and hence, reduces active vitamin D drugs.

Clinical Trial Registry: This study was registered at ClinicalTrials.gov and University Hospital Medical Information Network Clinical Trials Registry (UMIN-CTR) as NCT02214563 (registration date: 12/08/2014) and UMIN000011786 (registration date: 15/08/2014), respectively (please refer to the links below). ClinicalTrials.gov: https://clinicaltrials.gov/ct2/show/record/NCT02214563. UMIN-CTR: https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000017152&language=E.

Vitamin D ameliorates adipose browning in chronic kidney disease cachexia

Patients with chronic kidney disease (CKD) are often 25(OH)D3 and 1,25(OH)2D3 insufficient. We studied whether vitamin D repletion could correct aberrant adipose tissue and muscle metabolism in a mouse model of CKD-associated cachexia. Intraperitoneal administration of 25(OH)D3 and 1,25(OH)2D3 (75 μg/kg/day and 60 ng/kg/day respectively for 6 weeks) normalized serum concentrations of 25(OH)D3 and 1,25(OH)2D3 in CKD mice. Vitamin D repletion stimulated appetite, normalized weight gain, and improved fat and lean mass content in CKD mice. Vitamin D supplementation attenuated expression of key molecules involved in adipose tissue browning and ameliorated expression of thermogenic genes in adipose tissue and skeletal muscle in CKD mice. Furthermore, repletion of vitamin D improved skeletal muscle fiber size and in vivo muscle function, normalized muscle collagen content and attenuated muscle fat infiltration as well as pathogenetic molecular pathways related to muscle mass regulation in CKD mice. RNAseq analysis was performed on the gastrocnemius muscle. Ingenuity Pathway Analysis revealed that the top 12 differentially expressed genes in CKD were correlated with impaired muscle and neuron regeneration, enhanced muscle thermogenesis and fibrosis. Importantly, vitamin D repletion normalized the expression of those 12 genes in CKD mice. Vitamin D repletion may be an effective therapeutic strategy for adipose tissue browning and muscle wasting in CKD patients.

The effect of previous treatment with bisphosphonate and renal impairment on the response to denosumab in osteoporosis: a 'real-life' study

PURPOSE

To investigate changes in bone mineral density (BMD) following denosumab after previous bisphosphonate therapy and the impact of chronic kidney disease (CKD) on response.

METHODS

A retrospective study of 134 patients (11 M, 123 F) aged [mean (SD)] 72 [11] years on denosumab was undertaken. Ninety-five patients had previously been on oral and 28 on iv bisphosphonate. Lumbar spine (LS), total hip (TH) and femoral neck (FN) BMD were measured before treatment and at 2.7 [1.2] years. GFR was < 35 ml/min in 24 patients (18%). Ninety-four (18 M, 76 F) patients aged 71 [11] years transitioning to zoledronate were also studied.

RESULTS

BMD improved following denosumab [mean (SEM) % change LS: 6.0 (0.62) p < 0.001, TH: 2.28 (0.64) p < 0.001, FN: 1.9 (0.77) p = 0.045]. Changes at the TH and FN were lower in patients with GFR < 35 ml/min (Group B) compared to those with GFR > 35 ml/min (Group A) [% change TH; Group A: 2.9 (0.72), Group B: - 0.84 (1.28), p = 0.015, FN; Group A: 2.76 (0.86), Group B: - 1.47 (1.53), p = 0.025]. % change in BMD at the FN and PTH were negatively associated (r = - 0.25, p = 0.013). BMD changes were not different at 12-18 months between patients on denosumab compared to zoledronate [% change at LS: denosumab: 3.97% (0.85), zoledronate: 2.6% (0.5), p = 0.19 TH: denosumab: 0.97% (0.58), zoledronate: 0.92% (0.6), p = 0.95).

CONCLUSION

Denosumab increases BMD following previous bisphosphonate treatment and is comparable to zoledronate. Lower response seen at the hip in CKD is related to PTH concentrations.

Bone fracture risk factors in prevalent hemodialysis patients

Bone fractures are an important cause of morbidity and mortality in hemodialysis (HD) patients. The aim of this study was to quantify the incidence of fractures in a cohort of prevalent HD patients and evaluate its relationship with possible risk factors. We performed a retrospective analysis of 341 patients, since they started HD (median of 51 months). Demographic, clinical, and biochemical parameters as well as vascular calcifications (VC) were evaluated. Fifty-seven episodes of fracture were identified with a median HD vintage of 47 months (incidence rate of 31 per 1000 person-years). Age (p < 0.001), female gender (p < 0.001), lower albumin (p = 0.02), and higher VC score (p < 0.001) were independently associated with increased risk of fracture, while active vitamin D therapy (p = 0.03) was associated with decreased risk. A significantly higher risk of incident fracture was also associated with higher values of bone-specific alkaline phosphatase (bALP) (p = 0.01) and intact parathyroid hormone (iPTH) levels either < 300 pg/mL (p = 0.02) or > 800 pg/mL (p < 0.001) compared with 300-800 pg/mL. In conclusion, bone fracture incidence in HD patients is high and its risk increases with age, female gender, lower serum albumin, and with the presence of more VC. Prevalent HD patients with low or high iPTH levels or increased bALP also had a higher fracture risk. Therapy with active vitamin D seems to have a protective role. Assessment of fracture risk and management in dialysis patients at greatest risk requires further study.

Targeting Vitamin D Deficiency to Limit Exacerbations in Respiratory Diseases: Utopia or Strategy With Potential?

Patients with respiratory diseases such as cystic fibrosis, chronic obstructive pulmonary disease, or asthma often experience an acute worsening of respiratory symptoms, termed exacerbations. Although the course of exacerbations is disease specific, they are mostly triggered by a respiratory infection. Exacerbations often require hospitalization and are an important cause of mortality. Treatments of exacerbations aim to minimize the negative impact and to prevent subsequent events. Despite many existing therapy options, many patients do not benefit from therapy and suffer from recurrent events. Vitamin D deficiency is a worldwide problem and is extremely prevalent in these patients. Vitamin D, known for its calcemic effects, also has immunomodulatory and anti-infectious actions and can therefore be a possible agent to treat or prevent exacerbations. This review will focus on vitamin D as a potential candidate to treat or prevent exacerbations in CF, COPD, and asthma.

Seasonal variation of serum 25-hydroxyvitamin D and parameters of bone and mineral disorder in dialysis patients

BACKGROUND

Vitamin D deficiency is common among dialysis patients and may impact blood concentrations of calcium, phosphorus, intact parathyroid hormone (iPTH), and alkaline phosphatase (ALP). Seasonal variation of serum 25-hydroxyvitamin D [25(OH)D] concentrations has been well established for the general population; however, less is known about circannual variation in 25(OH)D as well as other parameters of mineral and bone disorder among dialysis patients.

METHOD

Based on 57,500 serum 25(OH)D measurements collected over two years from January 2009 to December 2010 among 25,025 dialysis patients, we evaluated the circannual variations in serum concentrations of 25(OH)D, calcium, phosphorus, iPTH, and ALP by a linear regression model with a cosinor function for the time period (month). We adjusted for potential confounders including case-mix variables, and ultraviolet index.

RESULTS

Serum 25(OH)D concentrations showed significant circannual variation and mean serum 25(OH)D was 3.2 ng/mL higher in summer than in winter. Furthermore, 25(OH)D concentration increased steadily by 1.3 ng/mL per year. While serum calcium concentrations showed statistically significant but clinically negligible seasonal variation (0.02 mg/dL in peak-trough difference), serum phosphorus did not follow such a pattern. Serum iPTH concentrations also showed a modest seasonal variation with 9% higher values in winter than in summer. Concordantly, ALP concentrations in the winter were 2% higher than in the summer time. Seasonal variation of 25(OH)D was greater in male (vs. female), African-American (vs. non-African-American), and younger (vs. older) dialysis patients.

CONCLUSION

Serum 25(OH)D and iPTH concentrations show seasonal variation among dialysis patients while the variation in other parameters of mineral and bone disorder was clinically irrelevant, if any. Serum 25(OH)D also showed a gradual increase over time. Clinicians and researchers should be aware of these changes when interpreting laboratory results in dialysis patients.

Hypocalcemic disorders

Calcium is vital for life, and extracellular calcium concentrations must constantly be maintained within a precise concentration range. Low serum calcium (hypocalcemia) occurs in conjunction with multiple disorders and can be life-threatening if severe. Symptoms of acute hypocalcemia include neuromuscular irritability, tetany, and seizures, which are rapidly resolved with intravenous administration of calcium gluconate. However, disorders that lead to chronic hypocalcemia often have more subtle manifestations. Hypoparathyroidism, characterized by impaired secretion of parathyroid hormone (PTH), a key regulatory hormone for maintaining calcium homeostasis, is a classic cause of chronic hypocalcemia. Disorders that disrupt the metabolism of vitamin D can also lead to chronic hypocalcemia, as vitamin D is responsible for increasing the gut absorption of dietary calcium. Treatment and management options for chronic hypocalcemia vary depending on the underlying disorder. For example, in patients with hypoparathyroidism, calcium and vitamin D supplementation must be carefully titrated to avoid symptoms of hypocalcemia while keeping serum calcium in the low-normal range to minimize hypercalciuria, which can lead to renal dysfunction. Management of chronic hypocalcemia requires knowledge of the factors that influence the complex regulatory axes of calcium homeostasis in a given disorder. This chapter discusses common and rare disorders of hypocalcemia, symptoms and workup, and management options including replacement of PTH in hypoparathyroidism.

Association of Pre-ESRD Serum Calcium With Post-ESRD Mortality Among Incident ESRD Patients: A Cohort Study

Albumin-corrected serum calcium (cSCa) decline at late stages of chronic kidney disease and rise after dialysis initiation. Although hypercalcemia is associated with higher mortality in end-stage renal disease (ESRD), there are scarce data on the impact of pre-ESRD cSCa on post-ESRD mortality. Therefore, we used a large national cohort of 21,826 US veterans who transitioned to dialysis in all US Department of Veterans Affairs health care facilities over 2009 to 2014 to examine the associations with all-cause and cause-specific post-ESRD mortality of (1) cSCa concentrations averaged over the last 6 months and (2) its rate of decline during the last 12 months before dialysis initiation. Mean concentrations and median rate of decline of cSCa were 9.3 ± 0.7 mg/dL and -0.15 (interquartile range -0.39 to 0.07) mg/dL/year, respectively. A total of 9596 patients died during the follow-up period (mean 1.9 years; total 41,541 patient-years) with an incidence rate of 23.1 per 100 patient-years. There was an independent linear association between higher cSCa with higher mortality (p_trend < 0.001). The mortality risk associated with cSCa ≥9.0 mg/dL was attenuated among active vitamin D users (p_interaction < 0.001). Patients with faster decline in cSCa showed lower mortality irrespective of baseline cSCa concentrations. These cSCa-mortality associations were stronger for noncardiovascular versus cardiovascular death. In conclusion, lower pre-ESRD cSCa and faster decline in cSCa were consistently and linearly associated with better post-ESRD survival among US veterans, especially for noncardiovascular death. Further studies are needed to determine if correcting hypocalcemia is beneficial or harmful and which intervention is preferred when indicated among patients transitioning to ESRD. © 2018 American Society for Bone and Mineral Research.

Maternal vitamin D deficiency increases the risk of adverse neonatal outcomes in the Chinese population: A prospective cohort study

BACKGROUND

Although vitamin D (vitD) deficiency is a common problem in pregnant women, in China, few studies have focused on the relationship between maternal vitD deficiency throughout the three trimesters and subsequent neonatal outcomes in China.

METHODS

Between 2015 and 2016, maternal serum and neonate cord blood samples were collected from 1978 mother-neonate pairs from Liuzhou city.

RESULTS

The mean concentrations of 25-hydroxy vitD (25(OH)D) were 16.17±6.27 and 15.23±5.43 ng/ml in the mother and neonate groups, respectively, and the prevalence values of vitD deficiency in the two groups were 78.18% and 83.27%, respectively. Logistic regression showed that maternal vitD deficiency independently increased the risk of gestational diabetes mellitus (GDM) (adjust OR, aOR 1.08; P = 0.026). A relatively lower risk of vitD deficiency was observed in the third trimester than in the first and second trimester (aOR 0.80; P = 0.004). VitD-calcium cosupplementation during pregnancy improves the vitD deficiency in both the maternal and neonatal groups (aOR 0.56, 0.66; P<0.001 and 0.021, respectively). Maternal vitD deficiency significantly increased the risk of neonatal low birth weight (LBW) (aOR 2.83; P = 0.005) and small-for-gestational-age (SGA) (aOR 1.17; P = 0.015). There was a positive correlation between maternal and neonatal vitD deficiency (r = 0.879, P<0.001). VitD supplementation during pregnancy significantly reduced the risk of giving birth to LBW infants (OR = 0.47, 95%CI = 0.33-0.68, P<0.001).

CONCLUSIONS

Further research focusing on the consumption of vitD with calcium during pregnancy and the consequential clinical outcomes in Chinese pregnant women is warranted.

Seasonal variations in transition, mortality and kidney transplantation among patients with end-stage renal disease in the USA

Background

Seasonal variations may exist in transitioning to dialysis, kidney transplantation and related outcomes among end-stage renal disease (ESRD) patients. Elucidating these variations may have major clinical and healthcare policy implications for better resource allocation across seasons.

Methods

Using the United States Renal Data System database from 1 January 2000 to 31 December 2013, we calculated monthly counts of transitioning to dialysis or first transplantation and deaths. Crude monthly transition fraction was defined as the number of new ESRD patients divided by all ESRD patients on the first day of each month. Similar fractions were calculated for all-cause and cause-specific mortality and transplantation.

Results

The increasing trend of the annual transition to ESRD plateaued during 2009-2012 (n = 126 264), and dropped drastically in 2013 (n = 117 372). Independent of secular trends, monthly transition to ESRD was lowest in July (1.65%) and highest in January (1.97%) of each year. All-cause, cardiovascular and infectious mortalities were lowest in July or August (1.32, 0.58 and 0.15%, respectively) and highest in January (1.56, 0.71 and 0.19%, respectively). Kidney transplantation was highest in June (0.33%), and this peak was mainly attributed to living kidney transplantation in summer months. Transplant failure showed a similar seasonal variation to naïve transition, peaking in January (0.65%) and nadiring in September (0.56%).

Conclusions

Transitioning to ESRD and adverse events among ESRD people were more frequent in winter and less frequent in summer, whereas kidney transplantation showed the reverse trend. The potential causes and implications of these consistent seasonal variations warrant more investigation.

Serum 25-hydroxyvitamin D concentration is not associated with glomerular filtration rate in a predominantly obese otherwise healthy population

Evidence from observational studies indicates a role for vitamin D in kidney function and progression to chronic kidney disease. Findings from animal studies have proposed underlying mechanisms including increased activation of the renin-angiotensin system, increased blood pressure, insulin resistance and chronic low-grade inflammation. However, human studies are limited by confounders arising from heterogeneous samples of participants. We examined the relationship between 25(OH)D and estimated glomerular filtration rate (eGFR) in a predominantly obese otherwise healthy and drug-naive population with no history of chronic kidney disease (CKD). One hundred and twenty one non-diabetic (75g oral glucose tolerance test; OGTT) volunteers (70 males and 51 females), aged 18-57 years participated in the study. Median 25(OH)D level was 37nmol/L with no difference by sex. Twenty six participants (21.5%) had 25(OH)D <25 nmol/L, 75 participants (62%) had 25(OH)D of 25-49.99nmol/L, and 20 participants (16.5%) had 25(OH)D ≥50nmol/L. In univariate analysis, 25(OH)D was related negatively to percent body fat and 2-h glucose level post OGTT. Mean (SD) eGFR was 113.1 (14.9)mL/min/1.73m², and in the multivariable analysis, it was related to age, sex, percent body fat and 2-h glucose level post OGTT, but not to 25(OH)D. Furthermore, there was no relationship between eGFR and 25(OH)D across BMI categories. Our data suggest that measuring 25(OH)D in predominantly obese otherwise healthy individuals with no history of CKD may not be beneficial in early recognition of kidney disease.

Association of pre-operative estimated GFR on post-operative pulmonary complications in laparoscopic surgeries

Despite a large body of evidence showing the pandemic of chronic kidney disease, the impact of pre-operative kidney function on the risk of post-operative pulmonary complications (PPCs) is not well known. We used multivariable logistic regression analyses with 3-level hierarchical adjustments to identify the association of pre-operative estimated glomerular filtration rate (eGFR) with PPCs in laparoscopic surgeries. Among 452,213 patients between 2005 and 2013 in the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) Database, a total of 3,727 patients (0.9%) experienced PPCs. We found a gradient association between lower eGFR and higher likelihood of PPCs in the unadjusted model. In the case-mix adjusted model, a reverse-J-shaped association was observed; a small albeit significant association with the highest eGFR category emerged. Further adjustment slightly attenuated these associations, but the PPCs risk in the eGFR groups of <30, 30-60, and ≥120 mL/min/1.73 m2 remained significant: odds ratios (95% confidence intervals) of 1.82 (1.54-2.16), 1.38 (1.24-1.54), and 1.28 (1.07-1.53), respectively (reference: 90-120 mL/min/1.73 m2). Our findings propose a need for careful pre-operative evaluation of cardiovascular and pulmonary functions and post-operative fluid management among patients with not only lower but also very high eGFR.

Potential application of klotho in human chronic kidney disease

The extracellular domain of transmembrane alpha-Klotho (αKlotho, hereinafter simply called Klotho) is cleaved by secretases and released into the circulation as soluble Klotho. Soluble Klotho in the circulation starts to decline early in chronic kidney disease (CKD) stage 2 and urinary Klotho possibly even earlier in CKD stage 1. Therefore soluble Klotho could serve as an early and sensitive marker of kidney function decline. Moreover, preclinical animal data support Klotho deficiency is not just merely a biomarker, but a pathogenic factor for CKD progression and extrarenal CKD complications including cardiovascular disease and disturbed mineral metabolism. Prevention of Klotho decline, re-activation of endogenous Klotho production or supplementation of exogenous Klotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiomyopathy, and alleviation of vascular calcification in CKD. Therefore Klotho is not only a diagnostic and/or prognostic marker for CKD, but the treatment of Klotho deficiency may be a promising strategy to prevent, retard, and decrease the burden of comorbidity in CKD.

Effects of vitamin D or its analogues on the mortality of patients with chronic kidney disease: an updated systematic review and meta-analysis

The objective of this study was to assess whether vitamin D (VD) treatment alters the overall all-cause and cardiovascular mortalities in a chronic kidney disease (CKD) population. We systematically searched PubMed, EMBASE, Web of Science, and Cochrane Central Register of Controlled Trials without language restriction, until the publication date of 22 February 2016. All related literatures that compared VD treatment with non-VD treatment and reported the mortality of patients with CKD (including those undergoing dialysis) were identified. Pooled risk ratios (RR) and 95% confidence intervals (CI) were calculated by using the random- and fixed-effects models. Randomised controlled trials (RCTs) that used the intention-to-treat principle and observational studies (OSs) were analysed separately. For this study, 38 studies involving 223 429 patients (17 RCTs, n=1819 and 21 OSs, n=221610) were included. In the OSs, VD treatment was significantly associated with reductions in both all-cause and cardiovascular mortalities; however, such significant association was not found in the RCTs. The existing RCTs do not provide sufficient or precise evidence that VD supplementation affects the mortality of patients with CKD, although subsets of patients that could potentially benefit from VD treatment can be identified by using the existing data from the RCTs. Nevertheless, large-size RCTs are needed in the future to assess any potential differences in survival prospectively.

Vitamin D3 induces vitamin D receptor and HDAC11 binding to relieve the promoter of the tight junction proteins

Intestinal epithelial barrier dysfunction and vitamin D (VitD)-deficiency play a critical role in a large number of diseases. The histone deacetylases (HDAC) are associated with a large number of immune diseases. This study tests a hypothesis that the interaction between VitD and HDAC is associated with the regulation of epithelial barrier functions. In this study, human intestinal epithelial cell line, T84 cells, was cultured into monolayers to be used as a model to test the epithelial barrier functions. We observed that in a VitD-deficient environment, the T84 monolayer barrier function was compromised. Exposure to calcitriol (the active form of VitD3) in the culture increased the expression of VitD receptor (VDR) in T84 cells. In a VitD-sufficient environment, VDR formed a complex with histone deacetylase-11 (HDAC11); the complex was markedly decreased in a VitD-deficient environment. We also observed that significantly more binding of HDAC11 to the promoter of the tight junction proteins inhibit the gene transcription activities of these loci in the VitD-deficient environment, which were abolished by the presence of calcitriol in the culture. In conclusion, the interaction between VDR and HDAC11 plays a crucial role in the maintenance of the epithelial barrier integrity.

Vitamin D Receptor Activator Use and Cause-specific Death among dialysis Patients: a Nationwide Cohort Study using Coarsened Exact Matching

Vitamin D receptor activators (VDRA) may exert pleiotropic effects on cardiovascular disease, malignancy, and infections among dialysis patients, but recent studies have mainly focused on cardiovascular outcomes. Among 8,675 patients who started dialysis in 2007 and who survived until January 1, 2010, listed in the Renal Data Registry of the Japanese Society for Dialysis Therapy, 5,365 VDRA users were matched to 3,203 non-users based on clinically relevant variables at the end of 2009 using the coarsened exact matching procedure. Until December 31, 2011, a total of 1,128 deaths occurred, of which 468 (42%) were cardiovascular deaths, 229 (20%) were infection-related deaths, and 141 (12%) were malignancy-related deaths. Multivariable survival analyses accounting for intra-region correlation revealed that VDRA use was significantly associated with lower rates of infection- and malignancy-related deaths [subhazard ratio 0.62 (95% CI, 0.52–0.73) and 0.70 (95% CI, 0.50–0.97), respectively] but not with cardiovascular death [subhazard ratio 0.86 (95% CI, 0.72–1.04)]. Future randomized clinical trials with a sufficient sample size and an adequate follow-up period are warranted to test the clinical effectiveness of VDRA on infection and malignancy, rather than cardiovascular disease, among dialysis patients.

Vitamin D Treatment Effect on Serum Endocan and High-Sensitivity C-Reactive Protein Levels in Renal Transplant Patients

Context:

Endocan is a marker showing endothelial dysfunction and inflammation. Significantly increased endocan levels have been observed in serum of patients with sepsis and cancer.

Objective:

Our aim was to investigate the relationship between vitamin D treatment and serum endocan and high-sensitivity C-reactive protein (hs-CRP) levels as inflammatory markers in transplant patients.

Design:

Prospective.

Setting:

Nephrology clinic.

Patients:

Thirty-eight renal transplant patients with serum 25-hydroxy-vitamin D (25-OH-vitamin D) levels below 20 ng/mL and transplanted at least 12 months.

Intervention:

One-time oral dose of 300 000 IU vitamin D3.

Main Outcome Measures:

Before and after vitamin D treatment, serum endocan, hs-CRP, calcium, phosphorus, and parathyroid hormone (PTH) levels were measured.

Results:

Median serum endocan and PTH values before vitamin D were significantly higher than those of after treatment values ( P = .001 and P < .001, respectively). On the other hand, serum total calcium and phosphorus levels before vitamin D treatment were lower than the values obtained after vitamin D treatment ( P = .0013 and P < .001, respectively). Serum hs-CRP was lower after vitamin D therapy than before, but the difference was not statistically significant ( P = .06). A moderate negative correlation was determined between endocan and 25-OH-vitamin D levels after treatment with vitamin D ( r = −.36, P = .02).

Conclusion:

This study has revealed that vitamin D treatment reduced markers of endothelial dysfunction in patients with renal transplantation and vitamin D deficiency.

αKlotho and Chronic Kidney Disease

Alpha-Klotho (αKlotho) protein is encoded by the gene, Klotho, and functions as a coreceptor for endocrine fibroblast growth factor-23. The extracellular domain of αKlotho is cleaved by secretases and released into the circulation where it is called soluble αKlotho. Soluble αKlotho in the circulation starts to decline in chronic kidney disease (CKD) stage 2 and urinary αKlotho in even earlier CKD stage 1. Therefore soluble αKlotho is an early and sensitive marker of decline in kidney function. Preclinical data from numerous animal experiments support αKlotho deficiency as a pathogenic factor for CKD progression and extrarenal CKD complications including cardiac and vascular disease, hyperparathyroidism, and disturbed mineral metabolism. αKlotho deficiency induces cell senescence and renders cells susceptible to apoptosis induced by a variety of cellular insults including oxidative stress. αKlotho deficiency also leads to defective autophagy and angiogenesis and promotes fibrosis in the kidney and heart. Most importantly, prevention of αKlotho decline, upregulation of endogenous αKlotho production, or direct supplementation of soluble αKlotho are all associated with attenuation of renal fibrosis, retardation of CKD progression, improvement of mineral metabolism, amelioration of cardiac function and morphometry, and alleviation of vascular calcification in CKD. Therefore in rodents, αKlotho is not only a diagnostic and prognostic marker for CKD but the enhancement of endogenous or supplement of exogenous αKlotho are promising therapeutic strategies to prevent, retard, and decrease the comorbidity burden of CKD.