Targeting serum calcium in chronic kidney disease and end-stage renal disease: is normal too high?

Associations between plasma metabolites and heavy metal exposure in residents of environmentally polluted areas

Heavy metals are commonly released into the environment through industrial processes such as mining and refining. The rapid industrialization that occurred in South Korea during the 1960s and 1970s contributed significantly to the economy of the country; however, the associated mining and refining led to considerable environmental pollution, and although mining is now in decline in South Korea, the detrimental effects on residents inhabiting the surrounding areas remain. The bioaccumulation of toxic heavy metals leads to metabolic alterations in human homeostasis, with disruptions in this balance leading to various health issues. This study used metabolomics to explore metabolomic alterations in the plasma samples of residents living in mining and refining areas. The results showed significant increases in metabolites involved in glycolysis and the surrounding metabolic pathways, such as glucose-6-phosphate, phosphoenolpyruvate, lactate, and inosine monophosphate, in those inhabiting polluted areas. An investigation of the associations between metabolites and blood clinical parameters through meet-in-the-middle analysis indicated that female residents were more affected by heavy metal exposure, resulting in more metabolomic alterations. For women, inhabiting the abandoned mine area, metabolites in the glycolysis and pentose phosphate pathways, such as ribose-5-phosphate and 3-phosphoglycerate, have shown a negative correlation with albumin and calcium. Finally, Mendelian randomization(MR) was used to determine the causal effects of these heavy metal exposure-related metabolites on heavy metal exposure-related clinical parameters. Metabolite biomarkers could provide insights into altered metabolic pathways related to exposure to toxic heavy metals and improve our understanding of the molecular mechanisms underlying the health effects of toxic heavy metal exposure.

Clinical Impact of the Use of Warfarin in Patients with Atrial Fibrillation Undergoing Maintenance Hemodialysis

Background: We evaluated the impact of warfarin use on the clinical outcomes of patients with atrial fibrillation who were undergoing hemodialysis (HD). Methods: A retrospective analysis was conducted utilizing data from patients undergoing maintenance HD who participated in HD quality assessment programs. Patients who were assigned the diagnostic code for atrial fibrillation (n = 4829) were included and divided into two groups based on the use of warfarin: No group (no warfarin prescriptions (n = 4009)), and Warfarin group (warfarin prescriptions (n = 820)). Results: Cox regression analyses revealed that the hazard ratio for all-cause mortality in the Warfarin group was 1.15 (p = 0.005) in univariate analysis and 1.11 (p = 0.047) in multivariable analysis compared to that of the No group. Hemorrhagic stroke was significantly associated with warfarin use, but no significant association between the use of warfarin and ischemic stroke or cardiovascular events was observed. The subgroup results demonstrated similar trends. Conclusions: Warfarin use is associated with a higher risk of all-cause mortality and hemorrhagic stroke, and has a neutral effect on ischemic stroke and cardiovascular events in patients with atrial fibrillation who are undergoing HD, compared to those who are not using warfarin.

The vitamin D receptor in osteoblastic cells but not secreted parathyroid hormone is crucial for soft tissue calcification induced by the proresorptive activity of 1,25(OH)2D3

The vitamin D receptor (VDR) is expressed most abundantly in osteoblasts and osteocytes (osteoblastic cells) in bone tissues and regulates bone resorption and calcium (Ca) and phosphate (P) homeostasis in association with parathyroid hormone (PTH). We previously reported that near-physiological doses of vitamin D compounds suppressed bone resorption through VDR in osteoblastic cells. We also found that supra-physiological doses of 1α,25-dihydroxyvitamin D3 [1,25(OH)2D3] induced bone resorption and hypercalcemia via VDR in osteoblastic cells. Here, we report that the latter, a proresorptive dose of 1,25(OH)2D3, causes soft tissue calcification through VDR in osteoblastic cells. High concentrations of vitamin D affect multiple organs and cause soft tissue calcification, with increases in bone resorption and serum Ca levels. Such a variety of symptoms is known as hypervitaminosis D, which is caused by not only high doses of vitamin D but also impaired vitamin D metabolism and diseases that produce 1,25(OH)2D3 ectopically. To clarify the biological process hierarchy in hypervitaminosis D, a proresorptive dose of 1,25(OH)2D3 was administered to wild-type mice in which bone resorption had been suppressed by neutralizing anti-receptor activator of NF-κB ligand (RANKL) antibody. 1,25(OH)2D3 upregulated the serum Ca x P product, concomitantly induced calcification of the aorta, lungs, and kidneys, and downregulated serum PTH levels in control IgG-pretreated wild-type mice. Pretreatment of wild-type mice with anti-RANKL antibody did not affect the down-regulation of PTH levels by 1,25(OH)2D3, but inhibited the increase of the serum Ca x P product and soft tissue calcification induced by 1,25(OH)2D3. Consistent with the effects of anti-RANKL antibody, VDR ablation in osteoblastic cells also did not affect the down-regulation of PTH levels by 1,25(OH)2D3, but suppressed the 1,25(OH)2D3-induced increase of the serum Ca x P product and calcification of soft tissues. Taken together with our previous results, these findings suggest that bone resorption induced by VDR signaling in osteoblastic cells is critical for the pathogenesis of hypervitaminosis D, but PTH is not involved in hypervitaminosis D.

Influence of time factor and albuminuria on characteristics of patients with type 2 diabetes Mellitus before, during and 1 year after COVID-19 recovery

BACKGROUND

The potential effects of time factor and albuminuria on the morbid alterations in patients with type 2 diabetes (T2D) and COVID-19 are still unclear. We aimed to address the morbid alterations and the potential effects of time factor and albuminuria on the patients' characteristics before, during, and 1 year after COVID-19 recovery.

METHODS

83 patients with T2D were included, at Mansoura University Hospital, Egypt (July 2021-December 2021). Data of detailed history, physical examination, laboratory tests were recruited from files of the patients. Diagnosis and resolution of COVID-19 were established by Real time polymerase chain reaction (RT-PCR) test of SARS-CoV2. Complete blood count (CBC), renal and hepatic function tests, multiple measures of morning spot urine albumin to creatinine ratio (urine ACR), glycosylated hemoglobin (HBA1c), lipid profile, erythrocyte sedimentation rate (ESR), C-reactive protein (CRP), Ferritin, neutrophil to lymphocyte ratio (NLR), vitamin D3, intact parathyroid hormone (intact PTH), serum calcium were applied to all participants.

RESULTS

Our participants had a mean age of 45 years, 60.2% male, 56.6% were hospitalized, and 25.3% were admitted to ICU for severe COVID-19. Albuminuria was prevalent in 71.1% before, 98.8% during, and 92.8% after COVID-19 recovery. Patients with albuminuria showed older age, longer duration of T2D, more frequent severe COVID-19 and hospitalization (p = 0.03, p < 0.001, p = 0.023& p = 0.025) respectively. Body mass index (BMI), mean arterial blood pressure, ESR, CRP, ferritin, NLR, HBA1c, triglycerides to high-density lipoprotein cholesterol (TG/HDL-C) ratio, vitamin D3, serum calcium, alkaline phosphatase (ALP), hepatic aminotransferases, and urine ACR showed significant alterations throughout the study (p < 0.001 for all). Although the interaction between time and albuminuria showed non-significant effect on all studied parameters, we noticed relevant main effects of time factor on Body mass index (BMI), HBA1c, glomerular filtration rate (eGFR), TG/HDL ratio, NLR, vitamin D3, (p < 0.001 for all). Moreover, albuminuria showed main effects on BMI, serum creatinine, and intact PTH (p = 0.019, 0.005 & <0.001), respectively.

CONCLUSION

The characteristics of patients with T2D significantly altered throughout the study. Time factor and albuminuria exerted relevant main effects on the patients' characteristics without significant effect of their interaction.

Admission eGFR predicts in-hospital mortality independently of admission glycemia and C-peptide in patients with type 2 diabetes mellitus and COVID-19

OBJECTIVE

Type 2 diabetes mellitus (T2DM) and impaired kidney function are associated with a higher risk of poor outcomes of COVID-19. We conducted a retrospective study in hospitalized T2DM patients with COVID-19 to assess the association between in-hospital mortality and admission values of different hematological/biochemical parameters, including estimated glomerular filtration rate (eGFR), plasma glucose and C-peptide (as a marker of beta-cell function).

METHODS

The study included T2DM patients with confirmed SARS-CoV-2 infection who were consecutively admitted to our Institution between October 1, 2020 and April 1, 2021.

RESULTS

Patients (n = 74) were categorized into survivors (n = 55) and non-survivors (n = 19). Non-survivors exhibited significantly higher median WBC count, D-dimer, neutrophil-to-lymphocyte ratio, hsCRP, and procalcitonin levels, as well as significantly lower median serum 25(OH)D levels compared to survivors. Non-survivors exhibited significantly higher median admission plasma glucose (APG) values compared to survivors (210 vs 166 mg/dL; p = 0.026). There was no statistically significant difference in median values of plasma C-peptide between non-survivors and survivors (3.55 vs 3.24 ng/mL; p = 0.906). A significantly higher percentage of patients with an eGFR < 60 mL/min/1.73 m² was observed in the non-survivor group as compared to the survivor group (57.9% vs 23.6%; p = 0.006). A multivariate analysis performed by a logistic regression model after adjusting for major confounders (age, sex, body mass index, major comorbidities) showed a significant inverse association between eGFR values and risk of in-hospital mortality (OR, 0.956; 95% CI, 0.931-0.983; p = 0.001). We also found a significant positive association between WBC count and risk of in-hospital mortality (OR, 1.210; 95% CI, 1.043-1.404; p = 0.011).

CONCLUSIONS

Admission eGFR and WBC count predict in-hospital COVID-19 mortality among T2DM patients, independently of traditional risk factors, APG and random plasma C-peptide. Hospitalized patients with COVID-19 and comorbid T2DM associated with impaired kidney function at admission should be considered at high risk for adverse outcomes and death.

The Usefulness of Calcium/Magnesium Ratio in the Risk Stratification of Early Onset of Renal Replacement Therapy

Background: A growing number of studies have reported a close relationship between high serum calcium (Ca)/low serum magnesium (Mg) and vascular calcification. Endothelial dysfunction and vascular inflammation seem plausible risk factors for the enhanced progression of kidney disease. The aim of this study was to evaluate the role of the Ca/Mg ratio as a predictor of the early onset of renal replacement therapy (RRT). Methods: This was a prospective study conducted in an outpatient low-clearance nephrology clinic, enrolling 693 patients with stages 4−5 of CKD. Patients were divided into two groups according to the start of renal replacement therapy (RRT). Results: The kidney’s survival at 120 months was 60% for a Ca−Mg ratio < 6 and 40% for a Ca−Mg ratio ≥ 6 (p = 0.000). Patients who started RRT had lower levels of Hb, Ca, Mg, albumin, and cholesterol and higher values of phosphorus, the Ca/Mg ratio, and PTH. High values of phosphorus and the Ca/Mg ratio and low levels of Mg and GFR were independent predictors of entry into RRT. A high Ca/Mg ratio, high phosphorus levels, and low levels of GFR were associated with a cumulative risk for initiation of RRT. Conclusions: In our population, the Ca/Mg ratio is an independent predictive factor for the initiation of a depurative technique.

Interpretation of Parathyroid Hormone Levels in Renal Impairment

Distinguishing between acute kidney injury and chronic kidney disease (CKD) in an emergency setting may pose a conundrum for physicians, especially when a patient’s medical history and records are unknown. Parathyroid hormone (PTH) has proved valuable as a marker of CKD and is frequently assayed for this reason. The use of PTH as a sole marker of CKD may be misleading in certain conditions, and for this reason, physicians need to interpret PTH values with caution. In patients with no existing medical records, it is vital to consider their overall clinical picture, an accurate interpretation of urinalysis and urine microscopy, and the PTH values when making the initial management decisions.

Nephrin and podocin mRNA detection in urine sediment of dogs with chronic kidney disease: preliminary observations

Introduction

Dogs with chronic kidney disease (CKD) may have alterations in the glomerular filtration barrier, including podocyte loss. Detection of podocyte mRNA in urine could be useful for assessing podocyturia in dogs with kidney disease. The objective of this study was to evaluate the presence of nephrin mRNA (NPHS1) and podocin mRNA (NPHS2) in urine sediments of dogs with naturally occurring CKD and healthy dogs.

Material and Methods

Twenty-four dogs, 14 with CKD and 10 as healthy controls, underwent clinical evaluation. The dogs with CKD were divided into two groups, according to the International Renal Interest Society criteria: stage 1 or 2 CKD (n = 5) and stage 3 or 4 CKD (n = 9). Urine was collected by catheterisation or free catch and RNA isolation from the urine sediments was optimised using glycogen as a co-precipitant. Detection of NPHS1 and NPHS2 in the sediment samples was performed using quantitative real-time PCR.

Results

Both types of mRNA were detected in samples from all groups, but the percentages of detection were higher in the group of dogs with stage 1 or 2 CKD and lower in the group of dogs with stage 3 or 4 disease.

Conclusion

Physiological podocyturia was observed in healthy dogs, and the results suggest differential podocyturia in dogs with CKD, according to the stage of the disease, i.e. an increase in podocyturia in dogs at stage 1 or 2 and a reduction in podocyturia in dogs at stage 3 or 4.

Interventions to Attenuate Vascular Calcification Progression in Chronic Kidney Disease: A Systematic Review of Clinical Trials

Background Vascular calcification is associated with cardiovascular morbidity and mortality in people with chronic kidney disease (CKD). Evidence-based interventions that may attenuate its progression in CKD remain uncertain.

Methods We conducted a systematic review of prospective clinical trials of interventions to attenuate vascular calcification in people with CKD, compare with placebo, another comparator, or standard of care. We included prospective clinical trials (randomized and nonrandomized) involving participants with stage 3-5D CKD or kidney transplant recipients; the outcome was vascular calcification measured using radiological methods. Quality of evidence was determined by the Cochrane risk of bias assessment tool and the Grading of Recommendations, Assessment, Development, and Evaluations (GRADE) method.

Results There were 77 trials (63 randomized) involving 6898 participants eligible for inclusion (median sample size, 50; median duration, 12 months); 58 involved participants on dialysis, 15 involved individuals with nondialysis CKD, and 4 involved kidney transplant recipients. Risk of bias was moderate over all. Trials involving magnesium and sodium thiosulfate consistently showed attenuation of vascular calcification. Trials involving intestinal phosphate binders, alterations in dialysate calcium concentration, vitamin K therapy, calcimimetics, and antiresorptive agents had conflicting or inconclusive outcomes. Trials involving vitamin D therapy and HMG-CoA reductase inhibitors did not demonstrate attenuation of vascular calcification. Mixed results were reported for single studies of exercise, vitamin E-coated or high-flux hemodialysis membranes, interdialytic sodium bicarbonate, SNF472, spironolactone, sotatercept, nicotinamide, and oral activated charcoal.

Conclusions Currently, there are insufficient or conflicting data regarding interventions evaluated in clinical trials for mitigation of vascular calcification in people with CKD. Therapy involving magnesium or sodium thiosulfate appears most promising, but evaluable studies were small and of short duration.

Ophiocordyceps lanpingensis polysaccharides alleviate chronic kidney disease through MAPK/NF-κB pathway

ETHNOPHARMACOLOGICAL RELEVANCE

Ophiocordyceps lanpingensis (O. lanpingensis) is a traditional ethno-medicine distributed in Eastern Himalayas, which has been used by local minorities to prevent and treat urinary diseases for hundreds of years. However, the corresponding active components and related pharmacological mechanism of such medication are not clear yet.

AIMS OF THE STUDY

This study was performed to investigate the effects and potential mechanisms of O. lanpingensis polysaccharides (OLP) in the treatment of chronic kidney disease (CKD) based on our previous research results.

MATERIALS AND METHODS

Methylation analysis was used to investigate the monosaccharide composition and glycosidic linkages in OLP. The animals were divided into the control group, CKD model group, losartan group and three different doses of OLP groups. The CKD mouse model was established by the adenine gavage. The histological changes of renal tissue were observed by Hematoxylin-eosin and Masson staining. Biochemical indicators, including blood urea nitrogen (BUN), serum creatinine (Scr), serum phosphorus (P), plasma calcium (Ca), reactive oxygen species (ROS), superoxide dismutase (SOD), glutathione peroxidase (GSH-PX) and malondialdehyde (MDA) were measured to evaluate the alleviation of CKD by OLP. Moreover, the expression levels of a series of cytokines related to the inflammation, apoptosis and fibrosis were analyzed to explore the possible mechanisms of OLP to treat CKD.

RESULTS

OLP is composed of three kinds of monosaccharides. There are eight kinds of glycosidic linkages in OLP, among which →4)-Glcp-(1→ is the main linkage. OLP could significantly attenuate CKD in mice and the tubulointerstitial damage was recovered to almost normal after the treatment of OLP. Compared with the CKD model group, the levels of Scr, BUN, MDA, P in OLP treatment groups were significantly decreased; and the levels of SOD and Ca were increased after OLP treatment. Furthermore, OLP could reduce the oxidative stress of the renal tissues, decrease the expression levels of pro-inflammatory factors through TLR4-mediated MAPK and NF-κB pathway, inhibit the apoptosis of renal cells by MAPK pathway, and relieve the renal fibrosis by down-regulating the expression of TGF-β1.

CONCLUSIONS

OLP is composed of three kinds of monosaccharides and →4)-Glcp-(1→ is the main glycosidic linkage in the polysaccharide. OLP could ameliorate CKD in mice by declining the oxidative stress, inflammation, apoptosis and fibrosis in the kidneys. The study provided some evidences for the potential application of OLP in alleviating CKD.

Misclassification of calcium status in end-stage kidney disease using albumin-adjusted calcium levels

BACKGROUND

Albumin-adjusted calcium remains widely used in clinical practice with guidelines for chronic kidney disease (CKD) mineral bone disorder recommending the use of serum calcium for monitoring. This is despite ionized calcium being the biologically active fraction. This study aimed to investigate the ability of total calcium and albumin-adjusted calcium to correctly assign calcium status in stage 5/5D CKD across non-dialysis, haemodialysis and peritoneal dialysis patients.

METHODS

Over a 6-months, 352 paired serum and ionized calcium samples were collected from stage 5 (n = 58) and 5D (n = 294, 196 haemodialysis, 98 peritoneal dialysis) CKD patients in a tertiary-hospital setting. Albumin-adjusted calcium was calculated using the modified-Payne formula. Ionized calcium was the reference standard. The agreement between the two methods in assigning calcium status was assessed using Cohen's weighted kappa (κ) statistic.

RESULTS

Albumin-adjusted calcium was a poor predictor of calcium status compared to ionized calcium in stage 5/5D CKD (observed agreement 0.42, weighted κ 0.20, 95% CI 0.15-0.26). Dialysis dependence was associated with worse agreement (observed agreement 0.38, weighted κ 0.14, 95% CI 0.09-0.19). Total calcium was more reliable, however, remained inaccurate. Calcium status was not more accurately classified in those with higher albumin levels ≥30 g/L (observed agreement 0.47, weighted κ 0.23, 95% CI 0.10-0.36).

CONCLUSION

Total calcium provides better approximation of calcium status than albumin-adjusted calcium in stage 5/5D CKD. Albumin-adjusted calcium tends to 'overcorrect' serum calcium upward. Clinicians should use ionized calcium where accurate measure of calcium is indicated, with total calcium used as the next best option where resources are limited.

Uremic Toxins Affecting Cardiovascular Calcification: A Systematic Review

Cardiovascular calcification is highly prevalent and associated with increased morbidity in chronic kidney disease (CKD). This review examines the impact of uremic toxins, which accumulate in CKD due to a failing kidney function, on cardiovascular calcification. A systematic literature search identified 41 uremic toxins that have been studied in relation to cardiovascular calcification. For 29 substances, a potentially causal role in cardiovascular calcification was addressed in in vitro or animal studies. A calcification-inducing effect was revealed for 16 substances, whereas for three uremic toxins, namely the guanidino compounds asymmetric and symmetric dimethylarginine, as well as guanidinosuccinic acid, a calcification inhibitory effect was identified in vitro. At a mechanistic level, effects of uremic toxins on calcification could be linked to the induction of inflammation or oxidative stress, smooth muscle cell osteogenic transdifferentiation and/or apoptosis, or alkaline phosphatase activity. For all middle molecular weight and protein-bound uremic toxins that were found to affect cardiovascular calcification, an increasing effect on calcification was revealed, supporting the need to focus on an increased removal efficiency of these uremic toxin classes in dialysis. In conclusion, of all uremic toxins studied with respect to calcification regulatory effects to date, more uremic toxins promote rather than reduce cardiovascular calcification processes. Additionally, it highlights that only a relatively small part of uremic toxins has been screened for effects on calcification, supporting further investigation of uremic toxins, as well as of associated post-translational modifications, on cardiovascular calcification processes.

RGS5 plays a significant role in renal cell carcinoma

Recent advances in biotechnology led to generation of large complex biological and clinical datasets that can be used to infer the underlying mechanism of many diseases and arrive at personalized treatments. One of these datasets are the whole genome profiles, including a good collection of publicly available human gene expression datasets. In this project, we analysed gene expression profiles of patients with renal cell carcinoma (RCC). We found that the regulator of G-protein signalling 5 (RGS5) might play a crucial role in initiation and progression of RCC, and it might be prognostic. We observed that a high expression level of RGS5 is associated with better survival months. Importantly, when the grade of tumour increases, the RGS5 expression level significantly decreases. Although there is no difference between expression level of RGS5 in male and female patients with primary tumours in the right kidney, among patients with primary tumours in the left kidney, females have a significantly higher RGS5 expression than male patients. Interestingly, we also observed a significant association between the high expression level of RGS5 and low serum calcium level and elevated white blood cells level.

Associations of Calcium from Food Sources Versus Phosphate Binders with Serum Calcium and FGF23 in Hemodialysis Patients

BACKGROUND

Dysregulated serum calcium and FGF23 are associated with increased mortality and morbidity rates in patients receiving hemodialysis. Preliminary data suggest serum calcium regulates FGF23 secretion independently of serum phosphate, parathyroid hormone, and 25-OH vitamin D. It is unclear to what extent dietary and prescription sources of calcium influence calcium and FGF23 levels, and whether they confound this relationship. In this cross-sectional analysis of a multi-ethnic cohort of prevalent hemodialysis patients, association of dietary calcium and prescribed calcium were examined against serum calcium and FGF23. Bi- and multivariable linear regression was used for all analyses.

RESULTS

81 patients (mean age 58 years, dialysis vintage 2 years, 51 men) participated. Dietary calcium was inversely associated with FGF23 (p = 0.04) however association of FGF23 with prescribed calcium did not reach statistical significance (0.08). In multivariable models, dietary calcium and prescribed calcium were associated in opposing directions with serum calcium (prescribed calcium; ß-coefficient = -0.35, p = 0.005 versus dietary calcium; ß-coefficient = 0.35, p = 0.03). FGF23 was independently associated with serum calcium (p = 0.007).

CONCLUSIONS

We found differing, sometimes opposing, associations between serum calcium and FGF23 levels when considering prescribed versus dietary sources of calcium. Serum calcium and FGF23 were strongly correlated regardless of possible confounders examined in this hemodialysis cohort. Dietary calcium was associated with higher serum calcium and lower FGF23 concentrations, while prescribed calcium was only inversely associated with serum calcium. Further studies are required to confirm these associations and determine causality.

The synergistic action of phosphate and interleukin-6 enhances senescence-associated calcification in vascular smooth muscle cells depending on p53

Cardiovascular calcification is associated with cardiovascular morbidity and mortality of patients with end-stage renal diseases (ESRD). Hyperphosphatemia and many of the inflammatory markers and mediators, including interleukin-6 (IL-6), are considered as the major risk factors of cardiovascular calcification. Although cellular senescence may be involved in cardiovascular calcification caused by phosphate overload and (or) IL-6 in patients with ESRD, less is known about the underlying mechanisms for phosphate- and IL-6-induced senescence-associated calcification of vascular smooth muscle cells (VSMCs). In the present study, we investigated the correlation between cellular senescence and vascular calcification induced by loading phosphate and (or) IL-6 in VSMCs. Our findings show that p53 plays a major role in senescence-associated vascular calcification induced by phosphate overload. IL-6 induces senescence-associated calcification in VSMCs depending upon activation of the IL-6/soluble IL-6 receptor (sIL-6R)/signal transducer and activator of transcription 3 (STAT3)/p53/p21 pathway. We demonstrate that the synergistic action of phosphate overload and IL-6 enhances senescence-associated calcification in a p53-dependent manner and is inhibited by an anti-aging agent (resveratrol) in a dose-dependent manner.

Association between serum calcium levels and prognosis, hematoma volume, and onset of cerebral hemorrhage in patients undergoing hemodialysis

BACKGROUND

High serum calcium levels should be avoided in patients on hemodialysis (HD) because they can induce cardiovascular diseases and worsen the patient's prognosis. In contrast, low serum calcium levels worsen the prognosis of patients with cerebral hemorrhage in the general population. So far, whether serum calcium levels in patients on HD are associated with cerebral hemorrhage remains unknown. This study aimed to reveal the association between serum calcium and cerebral hemorrhage in patients on HD, including in-hospital death, volume of hematoma, and onset of cerebral hemorrhage.

METHODS

This cross-sectional case-control study included 99 patients on HD with cerebral hemorrhage at a single center between July 1, 2007 and December 31, 2017. Controls included 339 patients on HD at a single HD center between July 1, 2011 and June 30, 2012. Data on serum calcium level, patient demographics, and comorbid conditions were collected, and associations between cerebral hemorrhage and subsequent death were evaluated by multivariate logistic regression analysis. Further, the association of these backgrounds and hematoma volume was evaluated by multiple regression analysis.

RESULTS

Of the 99 patients, 32 (32%) died from cerebral hemorrhage. The corrected serum calcium level (odds ratio [OR], 2.49; 95% confidence interval [CI], 1.43-4.35; P < 0.001) and antiplatelet drug use (OR, 3.95; 95% CI, 1.50-10.4; P = 0.005) had significant effects on the prognosis. Moreover, the corrected serum calcium (P = 0.003) and antiplatelet drug use (P = 0.01) were significantly correlated with hematoma volume. In the patients, the corrected serum calcium level (OR, 1.54; 95% CI, 1.07-2.22; P = 0.02) was associated with the onset of cerebral hemorrhage, as was pre-hemodialysis systolic blood pressure (per 10 mmHg) (OR, 1.40; 95% CI, 1.23-1.59; P < 0.001).

CONCLUSIONS

Although the precise mechanisms remain unknown, a high serum calcium level is associated with cerebral hemorrhage in patients on HD. Thus, we should pay attentions to a patient's calcium level.

Lower serum calcium is independently associated with CKD progression

Disturbances in calcium metabolism are common in individuals with chronic kidney disease (CKD), but whether they are associated with subsequent kidney function decline is less clear. In a CKD 3-5 cohort of 15,755 adult citizens of Stockholm with creatinine tests taken during 2006-2011 and concurrent calcium testing at cohort entry, we investigated the association between baseline serum calcium and the subsequent change in estimated glomerular filtration rate (eGFR, by CKD-EPI) decline using linear mixed models. Mean (SD) baseline corrected serum calcium was 9.6 (0.5) mg/dL. Mean (95%-confidence interval [CI]) eGFR decline was -0.82 (-0.90; -0.74) mL/min/1.73 m2/year. In advanced CKD stages, higher baseline serum calcium was associated with less rapid kidney function decline. The adjusted change (95%-CI) in eGFR decline associated with each mg/dL increase in baseline serum calcium was -0.10 (-0.28; 0.26), 0.39 (0.07; 0.71), 0.34 (-0.02; 0.70) and 0.68 (0.36; 1.00) mL/min/1.73 m2/year for individuals in CKD stage 3a, 3b, 4, and 5, respectively. In a subgroup of patients using vitamin D supplements, the association between baseline serum calcium and CKD progression was eliminated, especially in CKD stage 3b and 4. To conclude, in individuals with CKD stage 3b to 5, lower baseline corrected serum calcium, rather than higher baseline serum calcium, associated with a more rapid CKD progression. Lower serum corrected calcium seems to be indicative for vitamin D deficiency.