Association of low serum 25-hydroxyvitamin D levels and acute kidney injury in the critically ill. Crit Care Med. 2012;40:3170-3179. [PMID: 22975885 DOI: 10.1097/ccm.0b013e318260c928]

NETosis: an emerging therapeutic target in renal diseases

Introduction

Neutrophil extracellular traps (NETs) are web-like structures composed of nuclear and granular components. The primary role of NETS is to prevent the dissemination of microbes and facilitate their elimination. However, this process is accompanied by collateral proinflammatory adverse effects when the NET release becomes uncontrollable, or clearance is impaired. Although NET-induced organ damage is conducted primarily and indirectly via immune complexes and the subsequent release of cytokines, their direct effects on cells are also remarkable. NETosis plays a critical pathogenic role in several renal disorders, such as the early phase of acute tubular necrosis, anti-neutrophil cytoplasmic antibody-mediated renal vasculitis, lupus nephritis, thrombotic microangiopathies, anti-glomerular basement membrane disease, and diabetic nephropathy. Their substantial contribution in the course of these disorders makes them a desirable target in the therapeutic armamentarium. This article gives an in-depth review of the heterogeneous pathogenesis and physiological regulations of NETosis and its pivotal role in renal diseases. Based on the pathogenesis, the article also outlines the current therapeutic options and possible molecular targets in the treatment of NET-related renal disorders.

Methods

We carried out thorough literature research published in PubMed and Google Scholar, including a comprehensive review and analysis of the classification, pathomechanisms, and a broad spectrum of NET-related kidney disorders.

Conclusions

NETosis plays a pivotal role in certain renal diseases. It initiates and maintains inflammatory and autoimmune disorders, thus making it a desirable target for improving patient and renal outcomes. Better understanding and clinical translation of the pathogenesis are crucial aspects to treatment, for improving patient, and renal outcomes.

Associations between Serum 25-hydroxyvitamin D, Sun Exposure Time, Dietary Vitamin D Intake, and New-Onset Acute Kidney Injury among 413,169 UK Adults

BACKGROUND

The prospective associations of serum 25(OH)D, sun exposure time, and dietary vitamin D with risk of acute kidney injury (AKI) are unclear.

OBJECTIVES

We aimed to evaluate the relations of serum 25(OH)D, sun exposure time, and dietary vitamin D intake with new-onset AKI and examine whether genetic susceptibility modified such associations.

METHODS

A total of 413,169 participants (mean age was 56.4 y, 47.2% were male) from UK Biobank without prior AKI were included. Sun exposure time was expressed as time spent outdoors. Genetic risk scores were calculated by 263 single nucleotide polymorphisms, which showed significant associations with the estimated glomerular filtration rate. The primary outcome was new-onset AKI. Cox proportional hazards models were used to estimate the HRs and (95% CIs).

RESULTS

During a median follow-up duration of 12 y, 16,938 (4.1%) participates developed new-onset AKI. Compared with those with serum 25(OH)D <25 nmol/L, significantly lower risks of new-onset AKI were found between participants with 25(OH)D 25 to <50 nmol/L (adjusted HR: 0.76; 95% CI: 0.73, 0.80), and ≥50 nmol/L (adjusted HR: 0.69; 95% CI: 0.65, 0.72). Moreover, in summer, participants who spent ≥4 h outdoors per day (tertile 3) had a significantly lower risk of new-onset AKI (adjusted HR: 0.90; 95% CI: 0.86, 0.95) than those who spent <2 h outdoors per day (tertile 1). Similar results were found for time spent outdoors in winter. In addition, those in quintile 5 of dietary vitamin D intake showed a lower risk of new-onset AKI (≥4.2 μg/d, adjusted HR: 0.90; 95% CI: 0.82, 0.98) than those in quintile 1 (<1.0 μg/d). Genetic risks of kidney diseases did not significantly modify all the 3 above associations (all P-interactions >0.05).

CONCLUSIONS

Serum 25(OH)D concentrations, time spent outdoors, and dietary vitamin D intake were all inversely associated with new-onset AKI, independent of genetic risks for kidney diseases.

The Role of Vitamin D in SARS-CoV-2 Infection and Acute Kidney Injury

Vitamin D has been described as an essential nutrient and hormone, which can cause nuclear, non-genomic, and mitochondrial effects. Vitamin D not only controls the transcription of thousands of genes, directly or indirectly through the modulation of calcium fluxes, but it also influences the cell metabolism and maintenance specific nuclear programs. Given its broad spectrum of activity and multiple molecular targets, a deficiency of vitamin D can be involved in many pathologies. Vitamin D deficiency also influences mortality and multiple outcomes in chronic kidney disease (CKD). Active and native vitamin D serum levels are also decreased in critically ill patients and are associated with acute kidney injury (AKI) and in-hospital mortality. In addition to regulating calcium and phosphate homeostasis, vitamin D-related mechanisms regulate adaptive and innate immunity. Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections have a role in excessive proinflammatory cell recruitment and cytokine release, which contribute to alveolar and full-body endothelial damage. AKI is one of the most common extrapulmonary manifestations of severe coronavirus disease 2019 (COVID-19). There are also some correlations between the vitamin D level and COVID-19 severity via several pathways. Proper vitamin D supplementation may be an attractive therapeutic strategy for AKI and has the benefits of low cost and low risk of toxicity and side effects.

Vitamin D Supplementation in Critically Ill Patients: A Meta-Analysis of Randomized Controlled Trials

Randomized controlled trials (RCTs) have reported conflicting outcomes with the use of vitamin D in critically ill patients. With reporting of newer RCTs, we conducted this updated meta-analysis. Electronic databases were searched for RCTs comparing vitamin D with placebo in critically ill patients admitted to the intensive care unit (ICU). A random-effects meta-analysis was used to calculate the risk ratio (RR) and standardized mean difference (SMD) with a 95% confidence interval (CI). Eleven RCTs with a total of 2,187 patients (vitamin D: n = 1,120; placebo: n = 1,067) were included. Vitamin D when compared to placebo was associated with the decreased duration of mechanical ventilation (SMD = -0.50; 95% CI = [-0.97, -0.03]; p = 0.04) and ICU stay (SMD = -0.60; 95% CI = [-1.03, -0.16]; p = 0.007) without any difference in the mortality (RR = 0.85; 95% CI = [0.68, 1.04]; p = 0.12) and length of hospital stay (SMD = -0.21; 95% CI = (-0.51, 0.09); p = 0.18]. Subgroup analysis showed that parenteral vitamin D may reduce the risk of mortality (RR = 0.54; 95% CI = [0.35, 0.83], p = 0.005). Vitamin D supplementation in critically ill patients decreases the duration of mechanical ventilation and ICU stay. Further studies should identify specific groups of patients who will derive the most benefit from vitamin D supplementation.

Vitamin C Deficiency Causes Cell Type-Specific Epigenetic Reprogramming and Acute Tubular Necrosis in a Mouse Model

BACKGROUND

Vitamin C deficiency is found in patients with variable kidney diseases. However, the role of vitamin C as an epigenetic regulator in renal homeostasis and pathogenesis remains largely unknown.

METHODS

We showed that vitamin C deficiency leads to acute tubular necrosis (ATN) using a vitamin C-deficient mouse model (Gulo knock-out). DNA/RNA epigenetic modifications and injured S3 proximal tubule cells were identified in the vitamin C-deficient kidneys using whole-genome bisulfite sequencing, methylated RNA immunoprecipitation sequencing, and single-cell RNA sequencing.

RESULTS

Integrated evidence suggested that epigenetic modifications affected the proximal tubule cells and fenestrated endothelial cells, leading to tubule injury and hypoxia through transcriptional regulation. Strikingly, loss of DNA hydroxymethylation and DNA hypermethylation in vitamin C-deficient kidneys preceded the histologic sign of tubule necrosis, indicating the causality of vitamin C-induced epigenetic modification in ATN. Consistently, prophylactic supplementation of an oxidation-resistant vitamin C derivative, ascorbyl phosphate magnesium, promoted DNA demethylation and prevented the progression of cisplatin-induced ATN.

CONCLUSIONS

Vitamin C played a critical role in renal homeostasis and pathogenesis in a mouse model, suggesting vitamin supplementation may be an approach to lower the risk of kidney injury.

Effect of Anti-Inflammatory and Antimicrobial Cosupplementations on Sepsis Prevention in Critically Ill Trauma Patients at High Risk for Sepsis

Background: Sepsis development in patients with trauma is associated with bad prognosis. This study investigated the effect of immunomodulatory interventions in major trauma patients at high risk for sepsis. Methods: In a randomized, double-blinded, controlled design, severe trauma patients were stratified by leukocyte anti-sedimentation rate (LAR) test into high risk (HR) and low risk (LR) for sepsis. The HR patients were randomly allocated into intravenous vitamin C plus vitamin B1 (HR-CB), intramuscular vitamin D plus oral Lactobacillus probiotics (HR-DP), or control (HR-C) groups. The clinical trial was registered at clinicaltrials.gov (https://clinicaltrials.gov/show/NCT04216459). Outcomes: The primary outcome was Acute Physiologic Assessment and Chronic Health Evaluation score II (APACHE II) score. Secondary outcomes included sepsis incidence, changes in Sequential Organ Failure Assessment (SOFA) score, and serum monocyte chemoattractant protein-1 (MCP-1) on day 6 from baseline, 28-day mortality, intensive care unit (ICU), and hospital discharge. Results: The HR-DP, HR-CB, and LR groups showed a significantly lower incidence of sepsis development (20%, 20%, and 16%, respectively, versus 60% in the HR-C group, p-value = 0.004). The three groups also showed a significant improvement in APACHE II and SOFA scores. Besides, MCP-1 levels were significantly decreased in HR-DP and HR-CB groups compared to the HR-C group (p-value ≤ 0.05). Significantly decreased mortality (10% and 16% versus 60% in the HR-C group) and increased ICU discharge (95% and 84% versus 45% in the HR-C group) were observed in HR-CB and LR groups (p-value = 0.001). Conclusion: Both combinations of interventions improved APACHE II scores and reduced sepsis incidence in trauma patients. The LAR combined with injury severity score were good sepsis predictors.

Vitamin D insufficiency in COVID-19 and influenza A, and critical illness survivors: a cross-sectional study

OBJECTIVES

The steroid hormone vitamin D has roles in immunomodulation and bone health. Insufficiency is associated with susceptibility to respiratory infections. We report 25-hydroxy vitamin D (25(OH)D) measurements in hospitalised people with COVID-19 and influenza A and in survivors of critical illness to test the hypotheses that vitamin D insufficiency scales with illness severity and persists in survivors.

DESIGN

Cross-sectional study.

SETTING AND PARTICIPANTS

Plasma was obtained from 295 hospitalised people with COVID-19 (International Severe Acute Respiratory and emerging Infections Consortium (ISARIC)/WHO Clinical Characterization Protocol for Severe Emerging Infections UK study), 93 with influenza A (Mechanisms of Severe Acute Influenza Consortium (MOSAIC) study, during the 2009-2010 H1N1 pandemic) and 139 survivors of non-selected critical illness (prior to the COVID-19 pandemic). Total 25(OH)D was measured by liquid chromatography-tandem mass spectrometry. Free 25(OH)D was measured by ELISA in COVID-19 samples.

OUTCOME MEASURES

Receipt of invasive mechanical ventilation (IMV) and in-hospital mortality.

RESULTS

Vitamin D insufficiency (total 25(OH)D 25-50 nmol/L) and deficiency (<25 nmol/L) were prevalent in COVID-19 (29.3% and 44.4%, respectively), influenza A (47.3% and 37.6%) and critical illness survivors (30.2% and 56.8%). In COVID-19 and influenza A, total 25(OH)D measured early in illness was lower in patients who received IMV (19.6 vs 31.9 nmol/L (p<0.0001) and 22.9 vs 31.1 nmol/L (p=0.0009), respectively). In COVID-19, biologically active free 25(OH)D correlated with total 25(OH)D and was lower in patients who received IMV, but was not associated with selected circulating inflammatory mediators.

CONCLUSIONS

Vitamin D deficiency/insufficiency was present in majority of hospitalised patients with COVID-19 or influenza A and correlated with severity and persisted in critical illness survivors at concentrations expected to disrupt bone metabolism. These findings support early supplementation trials to determine if insufficiency is causal in progression to severe disease, and investigation of longer-term bone health outcomes.

Vitamin D/VDR in Acute Kidney Injury: A Potential Therapeutic Target

Despite many strategies and parameters used in clinical practice, the incidence and mortality of acute kidney injury (AKI) are still high with poor prognosis. With the development of molecular biology, the role of vitamin D and vitamin D receptor (VDR) in AKI is drawing increasing attention. Accumulated researches have suggested that Vitamin D deficiency is a risk factor of both clinical and experimental AKI, and vitamin D/VDR could be a promising therapeutic target against AKI. However, more qualitative clinical researches are needed to provide stronger evidence for the clinical application of vitamin D and VDR agonists in the future. Issues like the route and dosage of administration also await more attention. The present review aims to summarize the current works on the role of vitamin D/VDR in AKI and provides some new insight on its therapeutic potential.

Association Between Low Serum Vitamin D Levels and Sepsis: A Single-Center Study in Tehran, Iran

Background: Vitamin D insufficiency is common in critically ill patients. It is hypothesized that vitamin D deficiency would be associated with sepsis in the critically ill. Thus, the present study aimed to investigate the association between vitamin D and sepsis severity. Method: In this cross-sectional study, patients with sepsis referring to a university hospital in Tehran, Iran, from February 2018 to March 2019 were included. Plasma concentrations of vitamin D in critically ill subjects admitted were assessed. Data were analyzed using SPSS version 20.0. P-values less than 0.05 were considered statistically significant. Results: Among the investigated patients, the mean serum level of vitamin D3 was 19.03 ± 13.08 ng/mL. The prevalence of vitamin D insufficiency in critically ill subjects with sepsis was 100% (150/150). Only sex (P = 0.01) indicated a significant association with vitamin D. Patients suffering from severe sepsis had lower levels of vitamin D compared to the patients with non-severe sepsis (P = 0.07). Conclusions: The present study showed that all critically ill patients studied had vitamin D insufficiency. In line with the biological evidence, the present study suggests that vitamin D deficiency may predispose patients to sepsis. Further studies are needed to establish the causes and mechanisms underlying these interpretations.

Vitamin D supplementation for the treatment of COVID-19: a living systematic review

BACKGROUND

The role of vitamin D supplementation as a treatment for COVID-19 has been a subject of considerable discussion. A thorough understanding of the current evidence regarding the effectiveness and safety of vitamin D supplementation for COVID-19 based on randomised controlled trials is required.

OBJECTIVES

To assess whether vitamin D supplementation is effective and safe for the treatment of COVID-19 in comparison to an active comparator, placebo, or standard of care alone, and to maintain the currency of the evidence, using a living systematic review approach.

SEARCH METHODS

We searched the Cochrane COVID-19 Study Register, Web of Science and the WHO COVID-19 Global literature on coronavirus disease to identify completed and ongoing studies without language restrictions to 11 March 2021.

SELECTION CRITERIA

We followed standard Cochrane methodology. We included randomised controlled trials (RCTs) evaluating vitamin D supplementation for people with COVID-19, irrespective of disease severity, age, gender or ethnicity. We excluded studies investigating preventive effects, or studies including populations with other coronavirus diseases (severe acute respiratory syndrome (SARS) or Middle East respiratory syndrome (MERS)).

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methodology. To assess bias in included studies, we used the Cochrane risk of bias tool (ROB 2) for RCTs. We rated the certainty of evidence using the GRADE approach for the following prioritised outcome categories: individuals with moderate or severe COVID-19: all-cause mortality, clinical status, quality of life, adverse events, serious adverse events, and for individuals with asymptomatic or mild disease: all-cause mortality, development of severe clinical COVID-19 symptoms, quality of life, adverse events, serious adverse events.

MAIN RESULTS

We identified three RCTs with 356 participants, of whom 183 received vitamin D. In accordance with the World Health Organization (WHO) clinical progression scale, two studies investigated participants with moderate or severe disease, and one study individuals with mild or asymptomatic disease. The control groups consisted of placebo treatment or standard of care alone. Effectiveness of vitamin D supplementation for people with COVID-19 and moderate to severe disease We included two studies with 313 participants. Due to substantial clinical and methodological diversity of both studies, we were not able to pool data. Vitamin D status was unknown in one study, whereas the other study reported data for vitamin D deficient participants. One study administered multiple doses of oral calcifediol at days 1, 3 and 7,  whereas the other study gave a single high dose of oral cholecalciferol at baseline. We assessed one study with low risk of bias for effectiveness outcomes, and the other with some concerns about randomisation and selective reporting. All-cause mortality at hospital discharge (313 participants) We found two studies reporting data for this outcome. One study reported no deaths when treated with vitamin D out of 50 participants, compared to two deaths out of 26 participants in the control group (Risk ratio (RR) 0.11, 95% confidence interval (CI) 0.01 to 2.13). The other study reported nine deaths out of 119 individuals in the vitamin D group, whereas six participants out of 118 died in the placebo group (RR 1.49, 95% CI 0.55 to 4.04]. We are very uncertain whether vitamin D has an effect on all-cause mortality at hospital discharge (very low-certainty evidence). Clinical status assessed by the need for invasive mechanical ventilation (237 participants) We found one study reporting data for this outcome. Nine out of 119 participants needed invasive mechanical ventilation when treated with vitamin D, compared to 17 out of 118 participants in the placebo group (RR 0.52, 95% CI 0.24 to 1.13). Vitamin D supplementation may decrease need for invasive mechanical ventilation, but the evidence is uncertain (low-certainty evidence). Quality of life We did not find data for quality of life. Safety of vitamin D supplementation for people with COVID-19 and moderate to severe disease We did not include data from one study, because assessment of serious adverse events was not described and we are concerned that data might have been inconsistently measured. This study reported vomiting in one out of 119 participants immediately after vitamin D intake (RR 2.98, 95% CI 0.12 to 72.30). We are very uncertain whether vitamin D supplementation is associated with higher risk for adverse events (very low-certainty). Effectiveness and safety of vitamin D supplementation for people with COVID-19 and asymptomatic or mild disease We found one study including 40 individuals, which did not report our prioritised outcomes, but instead data for viral clearance, inflammatory markers, and vitamin D serum levels. The authors reported no events of hypercalcaemia, but recording and assessment of further adverse events remains unclear. Authors administered oral cholecalciferol in daily doses for at least 14 days, and continued with weekly doses if vitamin D blood levels were > 50 ng/mL.

AUTHORS' CONCLUSIONS

There is currently insufficient evidence to determine the benefits and harms of vitamin D supplementation as a treatment of COVID-19. The evidence for the effectiveness of vitamin D supplementation for the treatment of COVID-19 is very uncertain. Moreover, we found only limited safety information, and were concerned about consistency in measurement and recording of these outcomes. There was substantial clinical and methodological heterogeneity of included studies, mainly because of different supplementation strategies, formulations, vitamin D status of participants, and reported outcomes. There is an urgent need for well-designed and adequately powered randomised controlled trials (RCTs) with an appropriate randomisation procedure, comparability of study arms and preferably double-blinding. We identified 21 ongoing and three completed studies without published results, which indicates that these needs will be addressed and that our findings are subject to change in the future. Due to the living approach of this work, we will update the review periodically.

25-hydroxyvitamin D, Fibroblast Growth Factor 23, and Risk of Acute Kidney Injury Over 20 Years of Follow-Up

INTRODUCTION

Low serum 25-hydroxyvitamin D levels have been identified as a risk factor for acute kidney injury (AKI) among critically ill patients. Whether low 25-hydroxyvitamin D levels are associated with long-term incidence of hospitalization with AKI in the general population is unknown.

METHODS

Among 12,380 participants (mean age, 57 years; 24% black) in the Atherosclerosis Risk in Communities (ARIC) Study who attended visit 2 (1990-1992), we explored the association of serum 25-hydroxyvitamin D with incident hospitalization with AKI. Multivariable Cox models were used to estimate hazard ratios (HRs). We also examined the association of serum fibroblast growth factor 23 (FGF23) with AKI.

RESULTS

During a median follow-up of 24.3 years, 2145 participants had incident hospitalization with AKI (crude incidence rate: 8.3; 95% confidence interval [CI]: 8.0-8.7, per 1,000 person-years). In multivariable Cox models (including adjustment for kidney function), lower 25-hydroxyvitamin D and higher FGF23 levels were each significantly associated with an increased risk of AKI (HR: 1.35; 95% CI: 1.17-1.54, for lowest vs. highest quartile for 25-hydroxyvitamin D, and HR: 1.19; 95% CI: 1.05-1.36, for highest vs. lowest quartile for FGF23). The association was consistent across demographic and clinical subgroups, regardless of whether AKI was the primary diagnosis for hospitalization, and when adjusting for incident chronic kidney disease (CKD) or cardiovascular disease (CVD) as a time-varying covariate.

CONCLUSION

Among middle- to older-age adults in the community, low 25-hydroxyvitamin D and high FGF23 levels were independently associated with an increased risk of AKI. Future studies should explore underlying mechanisms linking these bone mineral metabolism markers with kidney injury.

Vitamin D and Acute Kidney Injury: A Two-Way Causality Relation and a Predictive, Prognostic, and Therapeutic Role of Vitamin D

Background: Acute kidney injury (AKI) constitutes a multi-factorially caused condition, which significantly affects kidney function and can lead to elevated risk of morbidity and mortality. Given the rising scientific evidence regarding vitamin D's (VitD's) multisystemic role, the connection between AKI and VitD is currently being studied, and the complex relation between them has started to be unraveled.

Methods: A systematic review had been conducted to identify the pathogenetic relation of VitD and AKI and the potential role of VitD as a biomarker and therapeutic–renoprotective factor.

Results: From 792 articles, 74 articles were identified that fulfilled the inclusion criteria. Based on these articles, it has been found that not only can VitD disorders (VitD deficiency or toxicity) cause AKI but, also, AKI can lead to great disruption in the metabolism of VitD. Moreover, it has been found that VitD serves as a novel biomarker for prediction of the risk of developing AKI and for the prognosis of AKI's severity. Finally, animal models showed that VitD can both ameliorate AKI and prevent its onset, suggesting its renoprotective effect.

Conclusion: There is a complex two-way pathogenetic relation between VitD disorders and AKI, while, concomitantly, VitD serves as a potential novel predictive–prognostic biomarker and a treatment agent in AKI therapy.

Ferrotoxicity and Its Amelioration by Calcitriol in Cultured Renal Cells

Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman’s method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4 ${}^{\prime }$ ,6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

Ferrotoxicity and Its Amelioration by Calcitriol in Cultured Renal Cells

Globally, acute kidney injury (AKI) is associated with significant mortality and an enormous economic burden. Whereas iron is essential for metabolically active renal cells, it has the potential to cause renal cytotoxicity by promoting Fenton chemistry-based oxidative stress involving lipid peroxidation. In addition, 1,25-dihydroxyvitamin D3 (calcitriol), the active form of vitamin D, is reported to have an antioxidative role. In this study, we intended to demonstrate the impact of vitamin D on iron-mediated oxidant stress and cytotoxicity of Vero cells exposed to iohexol, a low osmolar iodine-containing contrast media in vitro. Cultured Vero cells were pretreated with 1,25-dihydroxyvitamin D3 dissolved in absolute ethanol (0.05%, 2.0 mM) at a dose of 1 mM for 6 hours. Subsequently, iohexol was added at a concentration of 100 mg iodine per mL and incubated for 3 hours. Total cellular iron content was analysed by a flame atomic absorption spectrophotometer at 372 nm. Lipid peroxidation was determined by TBARS (thiobarbituric acid reactive species) assay. Antioxidants including total thiol content were assessed by Ellman's method, catalase by colorimetric method, and superoxide dismutase (SOD) by nitroblue tetrazolium assay. The cells were stained with DAPI (4',6-diamidino-2-phenylindole), and the cytotoxicity was evaluated by viability assay (MTT assay). The results indicated that iohexol exposure caused a significant increase of the total iron content in Vero cells. A concomitant increase of lipid peroxidation and decrease of total thiol protein levels, catalase, and superoxide dismutase activity were observed along with decreased cell viability in comparison with the controls. Furthermore, these changes were significantly reversed when the cells were pretreated with vitamin D prior to incubation with iohexol. Our findings of this in vitro model of iohexol-induced renotoxicity lend further support to the nephrotoxic potential of iron and underpin the possible clinical utility of vitamin D for the treatment and prevention of AKI.

Prevalence and Impact of Vitamin D Deficiency in Critically Ill Cancer Patients Admitted to the Intensive Care Unit

Vitamin D deficiency is frequent in cancer patients and a risk factor for morbidity and mortality during critical illness. This single-center retrospective study analyzed 25-hydroxyvitamin D levels in critically ill cancer patients (n = 178; hematologic, n = 108; solid, n = 70) enrolled in a prospective ICU registry. The primary analysis was the prevalence of vitamin D deficiency (<20 ng/mL) and the severe deficiency (≤12 ng/mL). Secondary analyses included risk factors for vitamin D deficiency and its impact on ICU, hospital, and 1-year mortality. The prevalence of vitamin D deficiency and severe deficiency was 74% (95% CI: 67-80%) and 54% (95% CI: 47-61%). Younger age, relapsed/refractory disease, and a higher sepsis-related organ failure assessment (SOFA) score were independent risk factors for vitamin D deficiency (p < 0.05). After adjusting for relapsed/refractory disease, infection, the SOFA score, and the early need for life-supporting interventions, severe vitamin D deficiency was an independent predictor of hospital mortality (OR: 2.21, 95% CI: 1.03-4.72, p = 0.04) and 1-year mortality (OR: 3.40, 95% CI: 1.50-7.71, p < 0.01), but not of ICU mortality. Conclusion: Vitamin D deficiency is common in critically ill cancer patients requiring ICU admission, but its impact on short-term mortality in this group is uncertain. The observed association of severe vitamin D deficiency with the post-ICU outcome warrants clinical consideration and further study.

Could Vitamins Help in the Fight Against COVID-19?

There are limited proven therapeutic options for the prevention and treatment of COVID-19. The role of vitamin and mineral supplementation or "immunonutrition" has previously been explored in a number of clinical trials in intensive care settings, and there are several hypotheses to support their routine use. The aim of this narrative review was to investigate whether vitamin supplementation is beneficial in COVID-19. A systematic search strategy with a narrative literature summary was designed, using the Medline, EMBASE, Cochrane Trials Register, WHO International Clinical Trial Registry, and Nexis media databases. The immune-mediating, antioxidant and antimicrobial roles of vitamins A to E were explored and their potential role in the fight against COVID-19 was evaluated. The major topics extracted for narrative synthesis were physiological and immunological roles of each vitamin, their role in respiratory infections, acute respiratory distress syndrome (ARDS), and COVID-19. Vitamins A to E highlighted potentially beneficial roles in the fight against COVID-19 via antioxidant effects, immunomodulation, enhancing natural barriers, and local paracrine signaling. Level 1 and 2 evidence supports the use of thiamine, vitamin C, and vitamin D in COVID-like respiratory diseases, ARDS, and sepsis. Although there are currently no published clinical trials due to the novelty of SARS-CoV-2 infection, there is pathophysiologic rationale for exploring the use of vitamins in this global pandemic, supported by early anecdotal reports from international groups. The final outcomes of ongoing trials of vitamin supplementation are awaited with interest.

Acute Kidney Injury and Pediatric Bone Health

Acute kidney injury (AKI) has been associated with deleterious impacts on a variety of body systems. While AKI is often accompanied by dysregulation of mineral metabolism-including alterations in calcium, phosphate, vitamin D, parathyroid hormone, fibroblast growth factor 23, and klotho-its direct effects on the skeletal system of children and adolescents remain largely unexplored. In this review, the pathophysiology of dysregulated mineral metabolism in AKI and its potential effects on skeletal health are discussed, including data associating AKI with fracture risk.

Vitamin D assessment in perioperative medicine and critical care : A prospective observational pilot study

BACKGROUND

There is controversy about the impact of acute illness on vitamin D levels. This study was carried out to assess the influence of perioperative fluid loading on 25-hydroxy-vitamin D [25(OH)D] levels. The study evaluated the clinical utility of a commonly available chemiluminescence assay (ECLIA, IDS-iSYS) and liquid chromatography/mass spectrometry (LC-MS/MS) in the diagnosis of vitamin D deficiency in this setting.

METHODS

In this prospective observational pilot study in adult patients undergoing cardiovascular surgery on cardiopulmonary bypass (CPB), blood samples drawn at preoperative baseline (t1), after weaning from CPB (t2), on intensive care unit (ICU) admission (t3) and on the first (t4) and second (t5) postoperative days were analyzed.

RESULTS

A total of 26 patients (130 samples) were included in this study. Fluid loading by CPB led to a median reduction of 25(OH)D by -22.6% (range -54.5% to -19.5%) between t1 and t2. Cohen's kappa (κ) for method agreement for vitamin D deficiency (tested cut-off values 20 ng/ml and 12 ng/ml), was κ = 0.291 (p < 0.001) and κ = 0.469 (p < 0.001), respectively. The mean difference between measurements by ECLIA and LC-MS/MS was 4.8 ng/ml (±5.7), Pearson's r for correlation was 0.73 (p < 0.001). The biologically inactive C3-epimer did not contribute to 25(OH)D levels assessed by LC-MS/MS.

CONCLUSION

The 25(OH)D measurements by chemiluminescence assays can noticeably deviate from those measured by LC-MS/MS, which can be considered the unequivocal gold standard. These assays may still be acceptably reliable in the screening for vitamin D deficiency, especially in the setting of low vitamin D levels. Stricter definitions, e.g. serum 25(OH)D levels lower than 12 ng/ml, may be used to diagnose deficiency with low false positive rate.

TRIAL REGISTRATION

DRKS00009216, German Clinical Trials Registry ( www.drks.de ).

Evaluation of serum 25-hydroxyvitamin D concentrations in a heterogeneous canine ICU population

OBJECTIVE

To identify the prevalence of low serum 25-hydroxyvitamin D (25-OH-D) concentrations in critically ill dogs and determine whether vitamin D concentration measured at admission correlates with illness severity and patient outcome.

DESIGN

Prospective observational study from December 2013 to July 2014.

SETTING

Private referral teaching hospital ICU.

ANIMALS

One hundred eleven critically ill dogs admitted to the ICU, and 28 apparently healthy control dogs.

INTERVENTIONS

Measurement of 25-OH-D concentration and assessment of physiological parameters required to calculate illness severity scores.

MEASUREMENTS AND MAIN RESULTS

Blood was sampled to measure serum 25-OH-D concentration, point-of-care laboratory data (packed cell volume, total plasma protein, venous blood gas, electrolytes, plasma lactate, and blood glucose concentration), platelet count, and serum albumin within 12 hours of admission. Primary disease etiologies were determined. Mentation score, Acute Patient Physiologic and Laboratory Evaluation (APPLE) fast score, length of ICU hospitalization, and survival to discharge were recorded. Low serum 25-OH-D concentrations were detected in 25% (28/111) of the ICU cohort; 25-OH-D concentrations (median; IQR) (89.2; 26.3 ng/mL [222; 140.0 nmol/L]) were significantly lower in hospitalized dogs compared with the healthy cohort (127.5; 44.5 ng/mL [318; 111.0 nmol/L]) (P < 0.0001). Serum 25-OH-D concentrations had a weak positive correlation with albumin (r = 0.34, P = 0.0003), but not with any other blood analyte evaluated. Serum concentration of 25-OH-D was also weakly correlated with APPLEfast score (r = 0.31, P = 0.001). 25-OH-D concentrations (median; IQR) were significantly higher in ICU dogs that survived to discharge (95.5; 55 ng/mL [238; 137 nmol/L]) compared with nonsurvivors (60.0; 54 ng/mL [149; 135 nmol/L]; P < 0.001).

CONCLUSIONS

Low serum 25-OH-D was recorded in one-quarter of critically ill dogs, and was significantly lower in nonsurvivors in comparison to survivors. There was weak correlation between serum 25-OH-D and illness severity. Further studies are required to clarify relationships between vitamin D status and outcome.

Serum vitamin D level was not associated with severity of ventilator associated pneumonia

BACKGROUND AND OBJECTIVE

Vitamin D deficiency is considered one of the most common nutritional deficiencies associated with weakened immune system and increased likelihood of sepsis. The current study was conducted to investigate the association between serum vitamin D level and the severity and prognosis of ventilator associated pneumonia (VAP) in inpatients in intensive care unit (ICU).

METHODS

Eighty-four consecutive patients with VAP were enrolled in this observational, prospective study conducted in the ICU of Besat Hospital, Hamadan. The patients were examined for serum 25-hydroxyvitamin D (vitD3) level and VAP severity and prognosis. Clinical pulmonary infection score was used for the diagnosis, and Sequential Organ Failure Assessment (SOFA) Score was used to determine the severity of VAP.

RESULTS

Low level serum vitD3 (under 30 ng/mL) was found in 66 (78.6%) patients. In this series of VAP patients, there were no significant differences in blood culture results, 14 and 28-day sepsis-associated mortality, mechanical ventilation duration, or SOFA Score on days 3, 7, and 14 between the low level and normal level vitD3 patients (p > 0.05).

CONCLUSION

Serum vitD3 level was not associated with mortality from VAP or complications due to sepsis in the inpatients in the ICU.

Pretreatment with Cholecalciferol Alleviates Renal Cellular Stress Response during Ischemia/Reperfusion-Induced Acute Kidney Injury

Background

Cellular stress is involved in ischemia/reperfusion- (I/R-) induced acute kidney injury (AKI). This study is aimed at investigating the effects of pretreatment with cholecalciferol on renal oxidative stress and endoplasmic reticulum (ER) stress during I/R-induced AKI.

Methods

I/R-induced AKI was established by cross-clamping renal pedicles for 90 minutes and then reperfusion. In the Chol + I/R group, mice were orally administered with three doses of cholecalciferol (25 μg/kg) at 1, 24, and 48 h before ischemia. Renal cellular stress and kidney injury were measured at different time points after reperfusion.

Results

I/R-induced AKI was alleviated in mice pretreated with cholecalciferol. In addition, I/R-induced renal cell apoptosis, as determined by TUNEL, was suppressed by cholecalciferol. Additional experiment showed that I/R-induced upregulation of renal GRP78 and CHOP was inhibited by cholecalciferol. I/R-induced renal IRE1α and eIF2α phosphorylation was attenuated by cholecalciferol. Moreover, I/R-induced renal GSH depletion, lipid peroxidation, and protein nitration were blocked in mice pretreated with cholecalciferol. I/R-induced upregulation of renal NADPH oxidases, such as p47phox, gp91phox, and nox4, was inhibited by cholecalciferol. I/R-induced upregulation of heme oxygenase- (HO-) 1, gshpx and gshrd, was attenuated in mice pretreated with cholecalciferol.

Conclusions

Pretreatment with cholecalciferol protects against I/R-induced AKI partially through suppressing renal cellular stress response.

Vitamin D status and supplementation in adult patients receiving extracorporeal membrane oxygenation

The prevalence of vitamin D deficiency in critical illness is known to be high and associated with adverse clinical outcomes. Patients receiving extracorporeal membrane oxygenation (ECMO) may be at increased risk of vitamin D deficiency due to high severity of acute illness. Challenges with drug dosing in ECMO patients are recognised due to increased volume of distribution and drug absorption to circuit components. To describe the prevalence of vitamin D deficiency in ECMO patients and the effect of intramuscular dosing of cholecalciferol on levels of vitamin D metabolites, and to compare these data with intensive care unit (ICU) patients not receiving ECMO, two prospective studies were performed sequentially: an observational study of 100 consecutive ICU patients and an interventional study assessing effects of intramuscular cholecalciferol in 50 ICU patients. The subgroup of patients who required ECMO support in each of these studies was analysed and compared to patients who did not receive ECMO. Twenty-four ECMO patients, 12 from the observational study and 12 from the interventional study (who received intramuscular cholecalciferol) were studied-21/24 (88%) ECMO patients were vitamin D deficient at baseline compared to 65/126 (52%) of non-ECMO patients (<i>P</i>=0.006). Of the 12 ECMO patients who received cholecalciferol, six patients (50%) achieved correction of deficiency compared to 36/38 (95%) non-ECMO patients (<i>P</i>=0.001). The prevalence of vitamin D deficiency is higher in ECMO patients compared to other critically ill adults. Correction of deficiency with single dose cholecalciferol is not reliable; higher or repeated doses should be considered to correct deficiency.

Vitamin D Supplementation in Mechanically Ventilated Patients in the Medical Intensive Care Unit

BACKGROUND

The utility of vitamin D (VITD) supplementation during critical illness and whether it may alter outcomes, including mortality and ventilator-free days, is unclear. We performed a retrospective cohort study in a generalizable population to investigate this question.

METHODS

We included all mechanically ventilated adults admitted to the medical intensive care unit (ICU) service at a tertiary center from 2009 to 2012 who were in the ICU for at least 72 hours. Patients were grouped as having received or not received VITD at any time during the first 7 days of their ICU stay, and we adjusted for the following covariates with multivariable analyses: simplified acute physiology score, age, gender, admission diagnosis, race/ethnicity, admission season, admission day of the week, and VITD supplementation prior to admission.

RESULTS

Among the 610 included patients, 281 received VITD, and 329 did not. There were no differences in outcomes between these groups. However, we did find significantly more ventilator-free days (21.0±2.6 [adjusted mean days±standard error] vs 17.6±2.4, P=0.04) and ICU-free days (18.5±2.5 vs 16.3±2.3, P=0.03) in patients who were taking VITD prior to admission (n=91) vs those who were not (n=519). No patients who were taking VITD before admission died vs 34.5% of those who were not (estimated odds ratio=4.9×10^-7 , 95% CI=3.1×10^-7 to 7.5×10^-7 , P<0.0001).

CONCLUSION

These results suggest that VITD supplementation during critical illness may not provide benefit and that further research investigating potential supplementation in ambulatory patients at high risk of ICU admission (eg, severe underlying chronic disease) is warranted.

Obesity attenuates serum 25-hydroxyvitamin D response to cholecalciferol therapy in critically ill patients

OBJECTIVES

The presence of obesity may confound cholecalciferol dosing in vitamin D-deficient patients owing to potentially decreased bioavailability. The aim of this retrospective study was to evaluate cholecalciferol therapy in vitamin D-deficient, critically ill trauma patients with and without obesity.

METHODS

Adult patients with severe traumatic injuries who had a serum 25-hydroxyvitamin D (25-OH vit D) <50nmol/L were prescribed 10 000 IU of liquid cholecalciferol daily. Efficacy was defined as achievement of a 25-OH vit D of 75 to 200nmol/L. Safety was evaluated by the presence of hypercalcemia (serum ionized calcium >1.32 mmol/L). Fifty-three patients (18 obese, 35 non-obese) were identified for study.

RESULTS

Despite similar baseline concentrations (36 ± 7 versus 37 ± 7 nmol/L; P = NS), 25-OH vit D response was attenuated for those with obesity after 1 and 2 wk of cholecalciferol therapy (51 ± 18 versus 66 ± 27nmol/L, P < 0.01; 68 ± 19 versus 92 ± 25nmol/L, P < 0.01, respectively). Patients with obesity also tended to experience less hypercalcemia (22% versus 49% of patients, respectively) post-cholecalciferol therapy.

CONCLUSION

Obesity alters the response to cholecalciferol therapy in critically ill patients with severe traumatic injuries.

Protein Intake, Nutritional Status and Outcomes in ICU Survivors: A Single Center Cohort Study

Background: We hypothesized that protein delivery during hospitalization in patients who survived critical care would be associated with outcomes following hospital discharge. Methods: We studied 801 patients, age ≥ 18 years, who received critical care between 2004 and 2012 and survived hospitalization. All patients underwent a registered dietitian formal assessment within 48 h of ICU admission. The exposure of interest, grams of protein per kilogram body weight delivered per day, was determined from all oral, enteral and parenteral sources for up to 28 days. Adjusted odds ratios for all cause 90-day post-discharge mortality were estimated by mixed- effects logistic regression models. Results: The 90-day post-discharge mortality was 13.9%. The mean nutrition delivery days recorded was 15. In a mixed-effect logistic regression model adjusted for age, gender, race, Deyo-Charlson comorbidity index, acute organ failures, sepsis and percent energy needs met, the 90-day post-discharge mortality rate was 17% (95% CI: 6–26) lower for each 1 g/kg increase in daily protein delivery (OR = 0.83 (95% CI 0.74–0.94; p = 0.002)). Conclusions: Adult medical ICU patients with improvements in daily protein intake during hospitalization who survive hospitalization have decreased odds of mortality in the 3 months following hospital discharge.

Vitamin D and critical illness: what endocrinology can learn from intensive care and vice versa

The prevalence of vitamin D deficiency in intensive care units ranges typically between 40 and 70%. There are many reasons for being or becoming deficient in the ICU. Hepatic, parathyroid and renal dysfunction additionally increases the risk for developing vitamin D deficiency. Moreover, therapeutic interventions like fluid resuscitation, dialysis, surgery, extracorporeal membrane oxygenation, cardiopulmonary bypass and plasma exchange may significantly reduce vitamin D levels. Many observational studies have consistently shown an association between low vitamin D levels and poor clinical outcomes in critically ill adults and children, including excess mortality and morbidity such as acute kidney injury, acute respiratory failure, duration of mechanical ventilation and sepsis. It is biologically plausible that vitamin D deficiency is an important and modifiable contributor to poor prognosis during and after critical illness. Although vitamin D supplementation is inexpensive, simple and has an excellent safety profile, testing for and treating vitamin D deficiency is currently not routinely performed. Overall, less than 800 patients have been included in RCTs worldwide, but the available data suggest that high-dose vitamin D supplementation could be beneficial. Two large RCTs in Europe and the United States, together aiming to recruit >5000 patients, have started in 2017, and will greatly improve our knowledge in this field. This review aims to summarize current knowledge in this interdisciplinary topic and give an outlook on its highly dynamic future.

Vitamin D to Prevent Lung Injury Following Esophagectomy-A Randomized, Placebo-Controlled Trial

OBJECTIVES

Observational studies suggest an association between vitamin D deficiency and adverse outcomes of critical illness and identify it as a potential risk factor for the development of lung injury. To determine whether preoperative administration of oral high-dose cholecalciferol ameliorates early acute lung injury postoperatively in adults undergoing elective esophagectomy.

DESIGN

A double-blind, randomized, placebo-controlled trial.

SETTING

Three large U.K. university hospitals.

PATIENTS

Seventy-nine adult patients undergoing elective esophagectomy were randomized.

INTERVENTIONS

A single oral preoperative (3-14 d) dose of 7.5 mg (300,000 IU; 15 mL) cholecalciferol or matched placebo.

MEASUREMENTS AND MAIN RESULTS

Primary outcome was change in extravascular lung water index at the end of esophagectomy. Secondary outcomes included PaO2:FIO2 ratio, development of lung injury, ventilator and organ-failure free days, 28 and 90 day survival, safety of cholecalciferol supplementation, plasma vitamin D status (25(OH)D, 1,25(OH)2D, and vitamin D-binding protein), pulmonary vascular permeability index, and extravascular lung water index day 1 postoperatively. An exploratory study measured biomarkers of alveolar-capillary inflammation and injury. Forty patients were randomized to cholecalciferol and 39 to placebo. There was no significant change in extravascular lung water index at the end of the operation between treatment groups (placebo median 1.0 [interquartile range, 0.4-1.8] vs cholecalciferol median 0.4 mL/kg [interquartile range, 0.4-1.2 mL/kg]; p = 0.059). Median pulmonary vascular permeability index values were significantly lower in the cholecalciferol treatment group (placebo 0.4 [interquartile range, 0-0.7] vs cholecalciferol 0.1 [interquartile range, -0.15 to -0.35]; p = 0.027). Cholecalciferol treatment effectively increased 25(OH)D concentrations, but surgery resulted in a decrease in 25(OH)D concentrations at day 3 in both arms. There was no difference in clinical outcomes.

CONCLUSIONS

High-dose preoperative treatment with oral cholecalciferol was effective at increasing 25(OH)D concentrations and reduced changes in postoperative pulmonary vascular permeability index, but not extravascular lung water index.

Vitamin D deficiency and supplementation in critical illness-the known knowns and known unknowns

The burgeoning literature on vitamin D deficiency and supplementation over the past decade or so has generated a greater understanding of some areas but also an appreciation of the many areas of equipoise. This is particularly relevant in the field of critical care with the heterogeneous patient populations, the severity and duration of illness and the frequency of comorbid conditions.

This review aims to summarise the current knowledge base of vitamin D deficiency within the context of critical illness—“the known knowns”—and also highlight the areas of recognised uncertainty—“the known unknowns”. It acknowledges the fact that there may well be other knowledge gaps of clinical relevance of which we are currently unaware—“the unknown unknowns”.

Increase of endocan, a new marker for inflammation and endothelial dysfunction, in acute kidney injury

OBJECTIVE:

In this study, the clinical relevance of the levels of serum endocan and 25-hydroxyvitamin D [25(OH)D] was investigated in patients with acute kidney injury (AKI). Endocan or the endothelial cell-specific molecule 1 is a soluble proteoglycan secreted by vascular endothelial cells. It plays a significant role in immunity, inflammation, and endothelial function.

METHODS:

A total of 39 patients with AKI (19 females, 20 males) and 38 healthy individuals (18 females, 20 males) were included in the study. The levels of serum endocan, vitamin D, and other biochemical parameters were compared between the two groups.

RESULTS:

In the AKI group, the values of serum creatinine, endocan, parathormone, phosphorus, and uric acid were found to be higher, and the total protein, albumin, and calcium levels were lower compared to the control group. There was no difference between the two groups in terms of the serum vitamin D, magnesium, alkaline phosphatase, and gamma-glutamyl transferase.

CONCLUSION:

In patients with AKI, an increased endocan level is a significant marker of inflammation and endothelial injury. In addition, these patients experience vitamin D deficiency.

22-oxacalcitriol prevents acute kidney injury via inhibition of apoptosis and enhancement of autophagy

BACKGROUND

The pathophysiology of ischemic acute kidney injury (AKI) is thought to include a complex interplay between tubular cell damage and regeneration. Several lines of evidences suggest a potential renoprotective effect of vitamin D. In this study, we investigated the effect of 22-oxacalcitriol (OCT), a synthetic vitamin D analogue, on renal fate in a rat model of ischemia reperfusion injury (IRI) induced acute kidney injury (AKI).

METHODS

22-oxacalcitriol (OCT) was administered via intraperitoneal (IP) injection before ischemia, and continued after IRI that was performed through bilateral clamping of the renal pedicles. 96 h after reperfusion, rats were sacrificed for the evaluation of autophagy, apoptosis, and cell cycle arrest. Additionally, assessments of toll-like receptors (TLR), interferon gamma (IFN-g) and sodium-hydrogen exchanger-1 (NHE-1) were also performed to examine their relations to OCT-mediated cell response.

RESULTS

Treatment with OCT-attenuated functional deterioration and histological damage in IRI induced AKI, and significantly decreased cell apoptosis and fibrosis. In comparison with IRI rats, OCT + IRI rats manifested a significant exacerbation of autophagy as well as reduced cell cycle arrest. Moreover, the administration of OCT decreased IRI-induced upregulation of TLR4, IFN-g and NHE-1.

CONCLUSION

These results demonstrate that treatment with OCT has a renoprotective effect in ischemic AKI, possibly by suppressing cell loss. Changes in the expression of IFN-g and NHE-1 could partially link OCT to the cell survival-promoted effects.

Vitamin D and critical illness outcomes

PURPOSE OF REVIEW

Although low vitamin D levels have been shown to be a risk factor for adverse outcomes in critical care, it is not clear to date if supplementation can alter such outcomes in all ICU patients. The focus of vitamin D research now is on interventional trials to identify a critically ill patient subset who may benefit from high-dose vitamin D supplementation.

RECENT FINDINGS

The VITdAL-ICU trial, a randomized, double-blind, placebo-controlled, single center trial of 475 heterogeneous critically ill patients, did not show improvement in hospital length of stay or overall mortality but did demonstrate in a secondary outcome that high-dose oral vitamin D3 improved mortality in patients with severe vitamin D deficiency.

SUMMARY

Vitamin D supplementation may represent a personalized and targeted therapy for critical illness. Vitamin D regulates over 1000 genes in the human genome, and the mechanism of action is influenced by gene polymorphisms and epigenetics. The study of the metabolomics, transcriptomics and epigenetics of vitamin D status and supplementation holds promise generating insights into critical illness outcomes.

Vitamin D status and its influence on outcomes following major burn injury and critical illness

Vitamin D deficiency is common among the general population. It is also observed in up to 76% of critically ill patients. Despite the high prevalence of hypovitaminosis D in critical illness, vitamin D is often overlooked by medical staff as the clinical implications and consequences of vitamin D deficiency in acute contexts remain to be fully understood. Vitamin D has a broad range of pleotropic effects on various processes and systems including the immune-inflammatory response. 1α,25-dihydroxyvitamin D (1,25(OH)₂D), has been shown to promote a tolerogenic immune response limiting deleterious inflammatory effects, modulation of the innate immune system, and enhancement of anti-microbial peptides. Vitamin D deficiency is frequently observed in critically ill patients and has been related to extrinsic causes (i.e., limited sunlight exposure), magnitude of injury/illness, or the treatment started by medical doctors including fluid resuscitation. Low levels of vitamin D in critically ill patients have been associated with sepsis, organ failure, and mortality. Despite this, there are subpopulations of critical illness, such as burn patients, where the literature regarding vitamin D status and its influence on outcomes remain insufficient. Thermal injury results in damage to both burned and non-burned tissues, as well as induces an exaggerated and persistent immune-inflammatory and hypermetabolic response. In this review, we propose potential mechanisms in which burn injury affects the vitamin D status and summarizes current literature investigating the influence of vitamin D status on outcomes. In addition, we reviewed the literature and trials investigating vitamin D supplementation in critically ill patients and discuss the therapeutic potential of vitamin D supplementation in burn and critically ill patients. We also highlight current limitations of studies that have investigated vitamin D status and supplementation in critical illness. Thermal injury influences vitamin D status. More studies investigating vitamin D depletion in burn patients and its influence on prognosis, via standardized methodology, are required to reach definitive conclusions and influence clinical practice.

Acute kidney injury predicts mortality in emergency general surgery patients

BACKGROUND

Patients undergoing Emergency General Surgery (EGS) have increased risk of complications and death. The risk of AKI in patients undergoing EGS, along with associated outcomes, is unknown.

METHODS

This two-institution observational study included adults admitted to intensive care units between 1997 and 2012. EGS was defined by 7 procedures occurring within 48 hours of ICU admission. The main outcome studied was AKI within 5 days, along with 90-day mortality.

RESULTS

In our cohort of 59,604 patients, 1758 (2.9%) underwent EGS. Risk of AKI in EGD patients was significantly increased relative to non-EGS patients, with adjusted odds of 1.7 (95%CI 1.40-1.94; P < 0.001). Risk of renal replacement for EGS patients was also increased, with odds of 1.8 (95%CI 1.37-2.46; P < 0.001). EGS patients were at significantly higher risk of 90-day mortality, with adjusted odds of 3.1 (95%CI 2.16-4.33,p < 0.001) for AKI and 4.5 (95%CI 2.58-7.96,p < 0.001) for AKI requiring renal replacement, relative to the absence of AKI.

CONCLUSIONS

EGS is a robust risk factor for AKI in critically ill patients, the development of which is strongly predictive of increased 90-day mortality.

Malnutrition, Critical Illness Survivors, and Postdischarge Outcomes: A Cohort Study

BACKGROUND

We hypothesized that preexisting malnutrition in patients who survived critical care would be associated with adverse outcomes following hospital discharge.

METHODS

We performed an observational cohort study in 1 academic medical center in Boston. We studied 23,575 patients, aged ≥18 years, who received critical care between 2004 and 2011 and survived hospitalization.

RESULTS

The exposure of interest was malnutrition determined at intensive care unit (ICU) admission by a registered dietitian using clinical judgment and on data related to unintentional weight loss, inadequate nutrient intake, and wasting of muscle mass and/or subcutaneous fat. The primary outcome was 90-day postdischarge mortality. Secondary outcome was unplanned 30-day hospital readmission. Adjusted odds ratios were estimated by logistic regression models adjusted for age, race, sex, Deyo-Charlson Index, surgical ICU, sepsis, and acute organ failure. In the cohort, the absolute risk of 90-day postdischarge mortality was 5.9%, 11.7%, 15.8%, and 21.9% in patients without malnutrition, those at risk of malnutrition, nonspecific malnutrition, and protein-energy malnutrition, respectively. The odds of 90-day postdischarge mortality in patients at risk of malnutrition, nonspecific malnutrition, and protein-energy malnutrition fully adjusted were 1.77 (95% confidence interval [CI], 1.23-2.54), 2.51 (95% CI, 1.36-4.62), and 3.72 (95% CI, 2.16-6.39), respectively, relative to patients without malnutrition. Furthermore, the presence of malnutrition is a significant predictor of the odds of unplanned 30-day hospital readmission.

CONCLUSIONS

In patients treated with critical care who survive hospitalization, preexisting malnutrition is a robust predictor of subsequent mortality and unplanned hospital readmission.

Prevalence and association of vitamin D deficiency and mortality in patients with severe sepsis

Background

Vitamin D is a steroid prohormone that regulates body calcium and phosphate metabolism. Recent studies have shown an association between low vitamin D status and high mortality in patients admitted to intensive care units. To date, there are limited data available specifically about severely septic patients in medical units.

Objectives

To determine the prevalence of vitamin D deficiency in severely septic patients and its clinical outcomes, including mortality rate.

Methods

A prospective observational study was conducted to investigate the prevalence of vitamin D deficiency and its association with 30-day mortality in patients with severe sepsis. Patients admitted to medical wards at our hospital between November 2014 and March 2015 were included in the study. A 25-hydroxyvitamin D level <20 ng/mL was defined as vitamin D deficiency, and <12 ng/mL as severe deficiency. For an association analysis, the patients were grouped into deficient versus not deficient and severely deficient versus not severely deficient.

Results

One hundred and ten eligible patients were enrolled. A total of 83 patients (75%) had vitamin D deficiency and 42 (38%) had severe deficiency. Despite an insignificant higher 30-day hospital mortality rate in vitamin D deficient versus non-deficient groups (16% vs 4%, p=0.18), the differences were significant between the severely deficient versus non-severe groups (23% vs 4%, p=0.02). The odds ratio of the 30-day mortality rate was 4.83 (95% confidence interval [CI], 0.60–38.77, p=0.14) for vitamin D deficiency and 7.69 (95% CI, 2.00–29.55, p=0.003) for severe deficiency.

Conclusion

The prevalence of vitamin D deficiency was very high in three-quarters of patients with severe sepsis. A significant higher mortality rate was observed, particularly in patients with severe vitamin D deficiency.

Acute Kidney Injury After Craniotomy Is Associated With Increased Mortality: A Cohort Study

BACKGROUND

Acute kidney injury (AKI) is a serious postoperative complication.

OBJECTIVE

To determine whether AKI in patients after craniotomy is associated with heightened 30-day mortality.

METHODS

We performed a 2-center, retrospective cohort study of 1656 craniotomy patients who received critical care between 1998 and 2011. The exposure of interest was AKI defined as meeting RIFLE (Risk, Injury, Failure, Loss of Kidney Function, and End-stage Kidney Disease) class risk, injury, and failure criteria, and the primary outcome was 30-day mortality. Adjusted odds ratios were estimated by multivariable logistic regression models with inclusion of covariate terms thought to plausibly interact with both AKI and mortality. Additionally, mortality in craniotomy patients with AKI was analyzed with a risk-adjusted Cox proportional hazards regression model and propensity score matching as a sensitivity analysis.

RESULTS

The incidences of RIFLE class risk, injury, and failure were 5.7%, 2.9%, and 1.3%, respectively. The odds of 30-day mortality in patients with RIFLE class risk, injury, or failure fully adjusted were 2.79 (95% confidence interval [CI], 1.76-4.42), 7.65 (95% CI, 4.16-14.07), and 14.41 (95% CI, 5.51-37.64), respectively. Patients with AKI experienced a significantly higher risk of death during follow-up; hazard ratio, 1.82 (95% CI, 1.34-2.46), 3.37 (95% CI, 2.36-4.81), and 5.06 (95% CI, 2.99-8.58), respectively, fully adjusted. In a cohort of propensity score-matched patients, RIFLE class remained a significant predictor of 30-day mortality.

CONCLUSION

Craniotomy patients who suffer postoperative AKI are among a high-risk group for mortality. The severity of AKI after craniotomy is predictive of 30-day mortality.

ABBREVIATIONS

AKI, acute kidney injuryAPACHE II, Acute Physiology and Chronic Health Evaluation IICI, confidence intervalCPT, Current Procedural TerminologyICD-9-CM, International Classification of Diseases, Ninth Revision, Clinical ModificationRIFLE, risk, injury, failure, loss of kidney function, and end-stage kidney diseaseRPDR, Research Patient Data Registry.

Severe vitamin D deficiency upon admission in critically ill patients is related to acute kidney injury and a poor prognosis

OBJECTIVES

To evaluate the prevalence of vitamin D deficiency in critically ill patients upon admission to an Intensive Care Unit (ICU) and its prognostic implications.

DESIGN

A single-center, prospective observational study was carried out from January to November 2015. Patients were followed-up on until death or hospital discharge.

SETTING

The department of Critical Care Medicine of a university hospital.

PATIENTS

All adults admitted to the ICU during the study period, without known factors capable of altering serum 25(OH)D concentration.

INTERVENTIONS

Determination of serum 25(OH)D levels within the first 24h following admission to the ICU.

MAIN VARIABLES OF INTEREST

Prevalence and mortality at 28 days.

RESULTS

The study included 135 patients, of which 74% presented deficient serum 25(OH)D levels upon admission to the ICU. Non-survivors showed significantly lower levels than survivors (8.14ng/ml [6.17-11.53] vs. 12ng/ml [7.1-20.30]; P=.04], and the serum 25(OH)D levels were independently associated to mortality (OR 2.86; 95% CI 1.05-7.86; P=.04]. The area under the ROC curve was 0.61 (95% CI 0.51-0.75), and the best cut-off point for predicting mortality was 10.9ng/ml. Patients with serum 25(OH)D<10.9ng/ml also showed higher acute kidney injury rates (13 vs. 29%; P=.02).

CONCLUSION

Vitamin D deficiency is highly prevalent upon admission to the ICU. Severe Vitamin D deficiency (25[OH]D<10.9ng/ml) upon admission to the ICU is associated to acute kidney injury and mortality.

Metabolome alterations in severe critical illness and vitamin D status

BACKGROUND

Metabolic homeostasis is substantially disrupted in critical illness. Given the pleiotropic effects of vitamin D, we hypothesized that metabolic profiles differ between critically ill patients relative to their vitamin D status.

METHODS

We performed a metabolomics study on biorepository samples collected from a single academic medical center on 65 adults with systemic inflammatory response syndrome or sepsis treated in a 20-bed medical ICU between 2008 and 2010. To identify key metabolites and metabolic pathways related to vitamin D status in critical illness, we first generated metabolomic data using gas and liquid chromatography mass spectroscopy. We followed this by partial least squares-discriminant analysis to identify individual metabolites that were significant. We then interrogated the entire metabolomics profile using metabolite set enrichment analysis to identify groups of metabolites and pathways that were differentiates of vitamin D status. Finally we performed logistic regression to construct a network model of chemical-protein target interactions important in vitamin D status.

RESULTS

Metabolomic profiles significantly differed in critically ill patients with 25(OH)D ≤ 15 ng/ml relative to those with levels >15 ng/ml. In particular, increased 1,5-anhydroglucitol, tryptophan betaine, and 3-hydroxyoctanoate as well as decreased 2-arachidonoyl-glycerophosphocholine and N-6-trimethyllysine were strong predictors of 25(OH)D >15 ng/ml. The combination of these five metabolites led to an area under the curve for discrimination for 25(OH)D > 15 ng/ml of 0.82 (95% CI 0.71-0.93). The metabolite pathways related to glutathione metabolism and glutamate metabolism are significantly enriched with regard to vitamin D status.

CONCLUSION

Vitamin D status is associated with differential metabolic profiles during critical illness. Glutathione and glutamate pathway metabolism, which play principal roles in redox regulation and immunomodulation, respectively, were significantly altered with vitamin D status.

Paricalcitol attenuates lipopolysaccharide-induced inflammation and apoptosis in proximal tubular cells through the prostaglandin E2 receptor EP4

Background

Vitamin D is considered to exert a protective effect on various renal diseases but its underlying molecular mechanism remains poorly understood. This study aimed to determine whether paricalcitol attenuates inflammation and apoptosis during lipopolysaccharide (LPS)-induced renal proximal tubular cell injury through the prostaglandin E₂ (PGE₂) receptor EP4.

Methods

Human renal tubular epithelial (HK-2) cells were pretreated with paricalcitol (2 ng/mL) for 1 hour and exposed to LPS (1 μg/mL). The effects of paricalcitol pretreatment in relation to an EP4 blockade using AH-23848 or EP4 small interfering RNA (siRNA) were investigated.

Results

The expression of cyclooxygenase-2, PGE₂, and EP4 were significantly increased in LPS-exposed HK-2 cells treated with paricalcitol compared with cells exposed to LPS only. Paricalcitol prevented cell death induced by LPS exposure, and the cotreatment of AH-23848 or EP4 siRNA offset these cell-protective effects. The phosphorylation and nuclear translocation of p65 nuclear factor-kappaB (NF-κB) were decreased and the phosphorylation of Akt was increased in LPS-exposed cells with paricalcitol treatment. AH-23848 or EP4 siRNA inhibited the suppressive effects of paricalcitol on p65 NF-κB nuclear translocation and the activation of Akt. The production of proinflammatory cytokines and the number of terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling-positive cells were attenuated by paricalcitol in LPS exposed HK-2 cells. The cotreatment with an EP4 antagonist abolished these anti-inflammatory and antiapoptotic effects.

Conclusion

EP4 plays a pivotal role in anti-inflammatory and antiapoptotic effects through Akt and NF-κB signaling after paricalcitol pretreatment in LPS-induced renal proximal tubule cell injury.

Vitamin D Deficiency in Human and Murine Sepsis

Supplemental Digital Content is available in the text.

Objectives:

Vitamin D deficiency has been implicated as a pathogenic factor in sepsis and ICU mortality but causality of these associations has not been demonstrated. To determine whether sepsis and severe sepsis are associated with vitamin D deficiency and to determine whether vitamin D deficiency influences the severity of sepsis.

Design, Setting, and Patients:

Sixty-one patients with sepsis and severe sepsis from two large U.K. hospitals and 20 healthy controls were recruited. Murine models of cecal ligation and puncture and intratracheal lipopolysaccharide were undertaken in normal and vitamin D deficient mice to address the issue of causality.

Measurements and Main Results:

Patients with severe sepsis had significantly lower concentrations of 25-hydroxyvitamin D₃ than patients with either mild sepsis or age-matched healthy controls (15.7 vs 49.5 vs 66.5 nmol/L; p = 0.0001). 25-hydroxyvitamin D₃ concentrations were significantly lower in patients who had positive microbiologic culture than those who were culture negative (p = 0.0023) as well as those who died within 30 days of hospital admission (p = 0.025). Vitamin D deficiency in murine sepsis was associated with increased peritoneal (p = 0.037), systemic (p = 0.019), and bronchoalveolar lavage (p = 0.011) quantitative bacterial culture. This was associated with reduced local expression of the cathelicidin-related antimicrobial peptide as well as evidence of defective macrophage phagocytosis (p = 0.029). In the intratracheal lipopolysaccharide model, 1,500 IU of intraperitoneal cholecalciferol treatment 6 hours postinjury reduced alveolar inflammation, cellular damage, and hypoxia.

Conclusions:

Vitamin D deficiency is common in severe sepsis. This appears to contribute to the development of the condition in clinically relevant murine models and approaches to correct vitamin D deficiency in patients with sepsis should be developed.

Outcomes of Vitamin D Supplementation in Adults Who are Deficient and Critically Ill: A Review of the Literature

Vitamin D deficiency is known to be common in the general population and has been linked to all-cause mortality. The classically recognized role of vitamin D is its involvement in calcium and phosphorous homeostasis and bone health. Recent evidence suggests that vitamin D may also play a role in other nonskeletal processes, such as anti-proliferation, immunity, regulation of hormone section, and muscle strength. An extensive literature review of vitamin D and critical illness from 2000 to 2015 (PubMed and CINAL) produced multiple observational studies revealing a high prevalence of vitamin D deficiency in intensive care patients. Many of these studies have indicated that there is an association between vitamin D deficiency and clinical outcomes such as mortality, sepsis, duration of mechanical ventilation, and length of stay. This review article provides an overview of vitamin D physiology in adults, a summary of observational studies on vitamin D deficiency in critical illness, and an examination of the few clinical trials on vitamin D supplementation in intensive care patients.

Vitamin D and acute myocardial infarction

Vitamin D deficiency is a prevalent condition, cutting across all ethnicities and among all age groups, and occurring in about 30%-50% of the population. Besides vitamin D established role in calcium homeostasis, its deficiency is emerging as a new risk factor for coronary artery disease. Notably, clinical investigations have suggested that there is an association between hypovitaminosis D and acute myocardial infarction (AMI). Not only has it been linked to incident AMI, but also to increased morbidity and mortality in this clinical setting. Moreover, vitamin D deficiency seems to predispose to recurrent adverse cardiovascular events, as it is associated with post-infarction complications and cardiac remodeling in patients with AMI. Several mechanisms underlying the association between vitamin D and AMI risk can be involved. Despite these observational and mechanistic data, interventional trials with supplementation of vitamin D are controversial. In this review, we will discuss the evidence on the association between vitamin D deficiency and AMI, in terms of prevalence and prognostic impact, and the possible mechanisms mediating it. Further research in this direction is warranted and it is likely to open up new avenues for reducing the risk of AMI.

Vitamin D Status and Supplementation in the Critically Ill

Vitamin D deficiency has recently been recognized as a widespread global disorder. Generally considered a direct extension of malnutrition, even subclinical hypovitaminosis D is now recognized in adequately nourished populations. Compared to the general population, the prevalence of hypovitaminosis D is greater in the critically ill population. In fact, several studies have shown poorer outcomes in critically ill patients discovered to be vitamin D deficient or insufficient. Controversy persists regarding vitamin D measurements, quantity of supplementation, and appropriate target level in various populations. Vitamin D has a vital role in calcium homeostasis and extra-skeletal health, such as immune function. Therefore, vitamin D supplementation may have a role for improving outcomes in critically ill patients. In this review, we will first discuss the metabolism and function of vitamin D under normal physiologic conditions. We will then explore the prevalence and prognostic value of vitamin D deficiency in critical illness. Finally, we will examine recent trials focusing on appropriate dosing, route of administration, and outcomes associated with vitamin D supplementation in the ICU.

Vitamin D deficiency in critically ill patients with traumatic injuries

Background

Vitamin D depletion has been associated with increased rate of infections, lengthened hospital stay, and worsened mortality for critically ill patients. The purpose of this study was to evaluate the prevalence and variables associated with vitamin D deficiency in critically ill patients with severe traumatic injuries.

Methods

Critically ill adult patients admitted to the trauma intensive care unit (ICU) between June 2013 and June 2014, referred to the nutrition support service for enteral or parenteral nutrition, and had a serum 25-hydroxyvitamin D (25-OH vitamin D) concentration determination were retrospectively evaluated. Patients were stratified as vitamin D sufficient, insufficient, deficient, or severely deficient based on a 25-OH vitamin D concentration of 30–80, 20–29.9, 13.1–19.9, and ≤13 ng/mL, respectively.

Results

One hundred and twenty-one patients out of 158 (76 %) patients were vitamin D deficient or severely deficient. Thirty-one patients (20 %) were insufficient and 6 (4 %) had a normal 25-OH vitamin D concentration. 25-OH vitamin D was determined 7.5 ± 5.1 days after ICU admission. African-Americans had a greater proportion of patients with deficiency or severe deficiency compared to other races (91 versus 64 %, P = 0.02). Penetrating gunshot or knife stab injury, African-American race, and obesity (elevated body mass index) were significantly associated with vitamin D deficiency or severe deficiency: OR 9.23 (1.13, 75.40), 4.0 (1.4, 11.58), and 1.12 (1.03, 1.23), P < 0.05, respectively.

Conclusions

The majority of critically ill patients with traumatic injuries exhibit vitamin D deficiency or severe deficiency. Penetrating injuries, African-American race, and obesity are significant risk factors for deficiency. Severity of injury, extent of inflammation (elevated C-reactive protein concentration), or hospital admission during the winter season did not significantly influence the prevalence of vitamin D deficiency.

Severe vitamin D deficiency is common in critically ill patients at a high northern latitude

BACKGROUND

Critically ill patients at southern latitudes have been shown to have low vitamin D levels that were associated with prolonged hospital stay. To our knowledge no studies have been conducted on vitamin D status amongst critically ill patients at high northern latitudes. Despite the Icelandic population traditionally taking vitamin D supplements, we hypothesized that the majority of critically ill patients in Reykjavik, Iceland have low vitamin D levels.

METHODS

This was a prospective observational study on 122 patients admitted to Landspitali University Hospital intensive care unit. Serum vitamin D (25(OH)D) was measured in all patients on two occasions (first and second day). The prevalence of vitamin D deficiency and its effect on hospital stay was calculated.

RESULTS

Only 9% of patients had vitamin D levels recommended for good health (>75 nmol/l) and 69% were deficient (25(OH)D < 50 nmol/l). The average difference between the first and second vitamin D samples was 2.8 nmol/l. Forty-three percentage of the severely vitamin D deficient stayed in the ICU for more than 4 days compared to 19% of patients with better status (P = 0.196).

DISCUSSION

Vitamin D deficiency is very common in critically ill patients at high northern latitudes and patients with severely deficient vitamin D levels had trend towards longer intensive care unit stay. Furthermore, 43% of the patients had vitamin D levels under 25 nmol/l that is associated with osteomalacia. It appears that a single vitamin D measurement gives a reasonable clue about the vitamin D status in critically ill patients.