Impact of different COVID-19 waves on kidney replacement therapy epidemiology and mortality: REMER 2020.

BACKGROUND: Kidney replacement therapy (KRT) confers the highest risk of death from coronavirus disease 2019 (COVID-19). However, most data refer to the early pandemic waves. Whole-year analysis compared with prior secular trends are scarce. METHODS: We present the 2020 REMER Madrid KRT registry, corresponding to the Spanish Region hardest hit by COVID-19. RESULTS: In 2020, KRT incidence decreased 12% versus 2019, while KRT prevalence decreased by 1.75% for the first time since records began and the number of kidney transplants (KTs) decreased by 16%. Mortality on KRT was 10.2% (34% higher than the mean for 2008-2019). The 2019-2020 increase in mortality was larger for KTs (+68%) than for haemodialysis (+24%) or peritoneal dialysis (+38%). The most common cause of death was infection [n = 419 (48% of deaths)], followed by cardiovascular [n = 200 (23%)]. Deaths from infection increased by 167% year over year and accounted for 95% of excess deaths in 2020 over 2019. COVID-19 was the most common cause of death (68% of infection deaths, 33% of total deaths). The bulk of COVID-19 deaths [209/285 (73%)] occurred during the first COVID-19 wave, which roughly accounted for the increased mortality in 2020. Being a KT recipient was an independent risk factor for COVID-19 death. CONCLUSIONS: COVID-19 negatively impacted the incidence and prevalence of KRT, but the increase in KRT deaths was localized to the first wave of the pandemic. The increased annual mortality argues against COVID-19 accelerating the death of patients with short life expectancy and the temporal pattern of COVID-19 mortality suggests that appropriate healthcare may improve outcomes.

Clinical Features of Asymptomatic SARS-CoV-2 Infection in Hemodialysis Patients.

BACKGROUND: CKD is a risk factor for severe COVID-19. However, the clinical spectrum of COVID-19 in hemodialysis patients is still poorly characterized. OBJECTIVE: To analyze the clinical spectrum of COVID-19 on hemodialysis patients. METHOD: A retrospective observational study was conducted on 66 hemodialysis patients. Nasopharyngeal swab PCR and serology for SARS-CoV-2, blood analysis, chest radiography, treatment, and outcomes were assessed. RESULTS: COVID-19 was diagnosed in 50 patients: 38 (76%) were PCR-positive and 12 (24%) were PCR-negative but developed anti-SARS-CoV-2 antibodies. By contrast, 17% of PCR-positive patients failed to develop detectable antibodies against SARS-CoV-2. Among PCR-positive patients, 5/38 (13%) were asymptomatic, while among PCR-negative patients 7/12 (58%) were asymptomatic (p = 0.005) for a total of 12/50 (24%) asymptomatic patients. No other differences were found between PCR-positive and PCR-negative patients. No differences in potential predisposing factors were found between asymptomatic and symptomatic patients except for a lower use of ACE inhibitors among asymptomatic patients. Asymptomatic patients had laboratory evidence of milder disease such as higher lymphocyte counts and oxygen saturation and lower troponin I and interleukin-6 levels than symptomatic patients. Overall mortality was 7/50 (14%) and occurred only in symptomatic PCR-positive patients in whom mortality was 7/33 (21%). CONCLUSIONS: Asymptomatic SARS-CoV-2 infection is common in hemodialysis patients, especially among patients with initial negative PCR that later seroconvert. Thus COVID-19 mortality in hemodialysis patients may be lower than previously estimated based on PCR tests alone.

TRAF3 Modulation: Novel Mechanism for the Anti-inflammatory Effects of the Vitamin D Receptor Agonist Paricalcitol in Renal Disease.

BACKGROUND: CKD leads to vitamin D deficiency. Treatment with vitamin D receptor agonists (VDRAs) may have nephroprotective and anti-inflammatory actions, but their mechanisms of action are poorly understood. METHODS: Modulation of the noncanonical NF-κB2 pathway and its component TNF receptor-associated factor 3 (TRAF3) by the VDRA paricalcitol was studied in PBMCs from patients with ESKD, cytokine-stimulated cells, and preclinical kidney injury models. RESULTS: In PBMCs isolated from patients with ESKD, TRAF3 protein levels were lower than in healthy controls. This finding was associated with evidence of noncanonical NF-κB2 activation and a proinflammatory state. However, PBMCs from patients with ESKD treated with paricalcitol did not exhibit these features. Experiments in cultured cells confirmed the link between TRAF3 and NF-κB2/inflammation. Decreased TRAF3 ubiquitination in K48-linked chains and cIAP1-TRAF3 interaction mediated the mechanisms of paricalcitol action.TRAF3 overexpression by CRISPR/Cas9 technology mimicked VDRA's effects. In a preclinical model of kidney injury, paricalcitol inhibited renal NF-κB2 activation and decreased renal inflammation. In VDR knockout mice with renal injury, paricalcitol prevented TRAF3 downregulation and NF-κB2-dependent gene upregulation, suggesting a VDR-independent anti-inflammatory effect of paricalcitol. CONCLUSIONS: These data suggest the anti-inflammatory actions of paricalcitol depend on TRAF3 modulation and subsequent inhibition of the noncanonical NF-κB2 pathway, identifying a novel mechanism for VDRA's effects. Circulating TRAF3 levels could be a biomarker of renal damage associated with the inflammatory state.

Serum Levels and Removal by Haemodialysis and Haemodiafiltration of Tryptophan-Derived Uremic Toxins in ESKD Patients.

Tryptophan is an essential dietary amino acid that originates uremic toxins that contribute to end-stage kidney disease (ESKD) patient outcomes. We evaluated serum levels and removal during haemodialysis and haemodiafiltration of tryptophan and tryptophan-derived uremic toxins, indoxyl sulfate (IS) and indole acetic acid (IAA), in ESKD patients in different dialysis treatment settings. This prospective multicentre study in four European dialysis centres enrolled 78 patients with ESKD. Blood and spent dialysate samples obtained during dialysis were analysed with high-performance liquid chromatography to assess uremic solutes, their reduction ratio (RR) and total removed solute (TRS). Mean free serum tryptophan and IS concentrations increased, and concentration of IAA decreased over pre-dialysis levels (67%, 49%, -0.8%, respectively) during the first hour of dialysis. While mean serum total urea, IS and IAA concentrations decreased during dialysis (-72%, -39%, -43%, respectively), serum tryptophan levels increased, resulting in negative RR (-8%) towards the end of the dialysis session (p < 0.001), despite remarkable Trp losses in dialysate. RR and TRS values based on serum (total, free) and dialysate solute concentrations were lower for conventional low-flux dialysis (p < 0.001). High-efficiency haemodiafiltration resulted in 80% higher Trp losses than conventional low-flux dialysis, despite similar neutral Trp RR values. In conclusion, serum Trp concentrations and RR behave differently from uremic solutes IS, IAA and urea and Trp RR did not reflect dialysis Trp losses. Conventional low-flux dialysis may not adequately clear Trp-related uremic toxins while high efficiency haemodiafiltration increased Trp losses.

Criteria for classification of protein-energy wasting in dialysis patients: impact on prevalence.

Malnutrition is highly prevalent in dialysis patients and associated with poor outcomes. In 2008, protein-energy wasting (PEW) was coined by the International Society of Renal Nutrition and Metabolism (ISRNM), as a single pathological condition in which undernourishment and hypercatabolism converge. In 2014, a new simplified score was described using serum creatinine adjusted for body surface area (sCr/BSA) to replace a reduction of muscle mass over time in the muscle wasting category. We have now compared PEW-ISRNM 2008 and PEW-score 2014 to evaluate the prevalence of PEW and the risk of death in 109 haemodialysis patients. This was a retrospective analysis of cross sectional data with a median prospective follow-up of 20 months. The prevalence of PEW was 41 % for PEW-ISRNM 2008 and 63 % for PEW-score 2014 (P <0·002). Using PEW-score 2014: twenty-nine patients (27 %) had severe malnutrition (PEW-score 2014 0-1) and forty (37 %) with moderate malnutrition (score 2). Additionally, thirty-three (30 %) patients had mild wasting and only seven patients (6 %) presented a normal nutritional status. sCr/BSA correlated with lean total mass (R 0·46. P<0·001). A diagnosis of PEW according to PEW-score 2014, but not according to PEW-ISRNM 2008, was significantly associated with short-term mortality (P=0·0349) in univariate but not in multivariate analysis (P=0·069). In conclusion, the new PEW-score 2014 incorporating sCr/BSA identifies a higher number of dialysis PEW patients than PEW-ISRNM 2008. Whereas PEW-score-2014 provides timelier and therefore more clinically relevant information, its association with early mortality needs to be confirmed in larger studies.

Reactions to Synthetic Membranes Dialyzers: Is there an Increase in Incidence?

BACKGROUND: Reactions to dialyzers used in dialysis have been reported more frequently in recent years. Evidence, however, shows that the reaction rate has remained stable for years. SUMMARY: One explanation for the apparent increase in publication frequency could be the lack of knowledge that dialyzer reactions may well occur with biocompatible membranes. Studies showed that the cause of these reactions is very diverse and varied, involving multiple materials. However, polyvinylpyrrolidone continues to be the main suspect, but without conclusive results. There are no differences between the different fibers, and although polysulfone is the most described, it is also the most used. Key Messages: The change to cellulose triacetate continues to be the most appropriate form of treatment. The classification of these reactions into type A and B complicates the diagnosis, and its true usefulness is in doubt.

Incidence of Hypersensitivity Reactions During Hemodialysis.

BACKGROUND/AIMS: A recent alert from Spanish health authorities warned of a higher incidence of reported hypersensitivity reactions to hemodialysis membranes with polysulfone, in the 2017 review of acute reactions to dialyzers found only published reports in the 21st century on polysulfone and its derivatives. The aim is to assess/evaluate the current incidence and characteristics of hypersensitivity reactions in hemodialysis patients. METHODS: A retrospective multicentre study in 9 Spanish hospitals evaluated patients in whom a hypersensitivity reaction required a change in dialyzer membrane. RESULTS: A total of 37 patients out of 1561 (2.37%) had hypersensitivity reactions and clinical, epidemiological and analytical data were available for 33 patients (2.11%). The membranes involved were polysulfone (n=23), polynephron (n=8), polyethersulfone (n=1) and polyacrylonitrile (n=1). This distribution reflected the frequency of use of membranes in the participating dialysis units. The reactions were described as type A in 18 cases and type B in 15 cases. There were no significant differences between the two types in clinical symptoms, the composition of the membrane involved, the method of sterilization, the season, or the time during the session in which they occurred. The most frequent symptom was dyspnea/breathlessness (64% of reactions). Eosinophilia was common (74%). 54% of the reactions occurred within the first 30 minutes of hemodialysis, 64% occurred during the first year of dialysis, and 54% required discontinuation of dialysis session. Cellulose triacetate was used as an alternative dialyzer in 78% of the cases. CONCLUSION: The incidence of hypersensitivity reactions was in the range found in reports from 20 years ago and is observed associated with synthetic membranes, not just polysulfones. Cellulose triacetate appears to be a good alternative for these patients.

Bisphenol A is an exogenous toxin that promotes mitochondrial injury and death in tubular cells.

BACKGROUND: Uremic toxins that accumulate in chronic kidney disease (CKD) contribute to CKD complications, such as CKD progression. Bisphenol A (BPA) is a ubiquitous environmental toxin, structurally related with p-cresol, that accumulates in CKD. Our aim was to characterize the nephrotoxic potential of BPA. Specifically, we addressed BPA toxicity over energy-demanding proximal tubular cells. METHODS: Cell death and oxidative stress were evaluated by flow cytometry and confocal microscopy in HK-2 human proximal tubular epithelial cells. Functional assays tested ATP, intracellular Ca2+ , mitochondrial function (tetramethylrhodamine methyl [TMRM]), oxygen consumption, Nrf2-binding, MitoSOX, and NADPH oxidase activity. Gene expression was assessed by qRT-PCR. RESULTS: Following acute exposure (24 hours), proximal tubular cell viability was decreased by BPA concentrations ≥50 µM while a seven-day exposure resulted in a progressive loss of cell viability at a nanomolar range. Within 24 hours, BPA promoted mitochondrial dysfunction leading to energy depletion and increased mitochondrial and cytoplasmic oxidative stress and apoptosis in a concentration-dependent manner. An antioxidant response was observed manifested by nuclear Nrf2 translocation and increased expression of the Nrf2 target genes Heme oxygenase 1 (HO-1) and NAD(P)H dehydrogenase [quinone] 1 (NQO-1). CONCLUSIONS: This study demonstrates for the first time that BPA causes mitochondrial injury, oxidative stress and apoptotic death in tubular cells. These results characterize BPA as an exogenous toxin that, similar to uremic toxins, may contribute to CKD progression.

Eculizumab in secondary atypical haemolytic uraemic syndrome.

Background: Complement dysregulation occurs in thrombotic microangiopathies (TMAs) other than primary atypical haemolytic uraemic syndrome (aHUS). A few of these patients have been reported previously to be successfully treated with eculizumab. Methods: We identified 29 patients with so-called secondary aHUS who had received eculizumab at 11 Spanish nephrology centres. Primary outcome was TMA resolution, defined by a normalization of platelet count (>150 × 10 9 /L) and haemoglobin, disappearance of all the markers of microangiopathic haemolytic anaemia (MAHA), and improvement of renal function, with a ≥25% reduction of serum creatinine from the onset of eculizumab administration. Results: Twenty-nine patients with secondary aHUS (15 drug-induced, 8 associated with systemic diseases, 2 with postpartum, 2 with cancer-related, 1 associated with acute humoral rejection and 1 with intestinal lymphangiectasia) were included in this study. The reason to initiate eculizumab treatment was worsening of renal function and persistence of TMA despite treatment of the TMA cause and plasmapheresis. All patients showed severe MAHA and renal function impairment (14 requiring dialysis) prior to eculizumab treatment and 11 presented severe extrarenal manifestations. A rapid resolution of the TMA was observed in 20 patients (68%), 15 of them showing a ≥50% serum creatinine reduction at the last follow-up. Comprehensive genetic and molecular studies in 22 patients identified complement pathogenic variants in only 2 patients. With these two exceptions, eculizumab was discontinued, after a median of 8 weeks of treatment, without the occurrence of aHUS relapses. Conclusion: Short treatment with eculizumab can result in a rapid improvement of patients with secondary aHUS in whom TMA has persisted and renal function worsened despite treatment of the TMA-inducing condition.

The Choice of Hemodialysis Membrane Affects Bisphenol A Levels in Blood.

Bisphenol A (BPA), a component of some dialysis membranes, accumulates in CKD. Observational studies have linked BPA exposure to kidney and cardiovascular injury in humans, and animal studies have described a causative link. Normal kidneys rapidly excrete BPA, but insufficient excretion may sensitize patients with CKD to adverse the effects of BPA. Using a crossover design, we studied the effect of dialysis with BPA-containing polysulfone or BPA-free polynephron dialyzers on BPA levels in 69 prevalent patients on hemodialysis: 28 patients started on polysulfone dialyzers and were switched to polynephron dialyzers; 41 patients started on polynephron dialyzers and were switched to polysulfone dialyzers. Results were grouped for analysis. Mean BPA levels increased after one hemodialysis session with polysulfone dialyzers but not with polynephron dialyzers. Chronic (3-month) use of polysulfone dialyzers did not significantly increase predialysis serum BPA levels, although a trend toward increase was detected (from 48.8±6.8 to 69.1±10.1 ng/ml). Chronic use of polynephron dialyzers reduced predialysis serum BPA (from 70.6±8.4 to 47.1±7.5 ng/ml, P<0.05). Intracellular BPA in PBMCs increased after chronic hemodialysis with polysulfone dialyzers (from 0.039±0.002 to 0.043±0.001 ng/10(6) cells, P<0.01), but decreased with polynephron dialyzers (from 0.045±0.001 to 0.036±0.001 ng/10(6) cells, P<0.01). Furthermore, chronic hemodialysis with polysulfone dialyzers increased oxidative stress in PBMCs and inflammatory marker concentrations in circulation. In vitro, polysulfone membranes released significantly more BPA into the culture medium and induced more cytokine production in cultured PBMCs than did polynephron membranes. In conclusion, dialyzer BPA content may contribute to BPA burden in patients on hemodialysis.

Circulating fibroblast growth factor-23 plasma levels predict adverse cardiovascular outcomes in patients with diabetes mellitus with coronary artery disease.

BACKGROUND: Abnormalities of fibroblast growth factor-23 (FGF-23) plasma levels predict adverse outcomes in patients with coronary artery disease. However, FGF-23 has a different behaviour in the presence of type 2 diabetes mellitus (T2D). We explored whether the presence of T2D affects the predictive power of FGF-23. METHODS: In 704 patients with stable coronary artery disease, FGF-23, calcidiol, parathormone (PTH) and phosphate plasma levels were prospectively assessed. The primary outcome was the development of acute ischemic events (acute coronary syndrome, stroke or transient ischemic attack), heart failure or death. RESULTS: One hundred seventy-three (24.6%) patients had T2D, without differences in age, sex or estimated glomerular filtration rate as compared with non-diabetic patients. Serum PTH was lower and phosphate higher in T2D than in non-diabetic patients, without differences in FGF-23 or calcidiol levels. During follow-up (2.15 ± 0.99 years), 26 (15.2%) T2D and 51 (9.6%) non-diabetic patients developed the outcome (p = 0.048). T2D patients who developed the outcome had higher FGF-23 [112.0 (59.9, 167.6) vs 68.9 (54.2, 93.0) RU/mL; p = 0.002], PTH [71.3 (47.3, 106.6) vs 51.9 (40.8, 66.2) pg/mL; p = 0.004) and phosphate (3.53 ± 0.71 vs 3.25 ± 0.50 mg/dL; p = 0.017) levels than T2D subjects who remained stable. These differences were not significant in non-diabetic patients. By multivariable Cox proportional hazard model, FGF-23 predicted independently the outcome in T2D patients [hazard ratio = 1.277; 95% CI (1.132, 1.442)] but not in those without T2D. CONCLUSIONS: FGF-23 plasma levels predict adverse cardiovascular outcomes in coronary artery disease patients who have T2D but not in those without T2D. This finding should be confirmed in larger studies. Copyright © 2016 John Wiley & Sons, Ltd.

Important abnormalities of bone mineral metabolism are present in patients with coronary artery disease with a mild decrease of the estimated glomerular filtration rate.

Chronic kidney disease (CKD)-mineral and bone disorder (MBD) is characterized by increased circulating levels of parathormone (PTH) and fibroblast growth factor 23 (FGF23), bone disease, and vascular calcification, and is associated with adverse outcomes. We studied the prevalence of mineral metabolism disorders, and the potential relationship between decreased estimated glomerular filtration rate (eGFR) and CKD-MBD in coronary artery disease patients in a cross-sectional study of 704 outpatients 7.5 ± 3.0 months after an acute coronary syndrome. The mean eGFR (CKD Epidemiology Collaboration formula) was 75.8 ± 19.1 ml/min/1.73 m(2). Our patients showed lower calcidiol plasma levels than a healthy cohort from the same geographical area. In the case of men, this finding was present despite similar creatinine levels in both groups and older age of the healthy subjects. Most patients (75.6 %) had an eGFR below 90 ml/min/1.73 m(2) (eGFR categories G2-G5), with 55.3 % of patients exhibiting values of 60-89 ml/min/1.73 m(2) (G2). PTH (r = -0.3329, p < 0.0001) and FGF23 (r = -0.3641, p < 0.0001) levels inversely correlated with eGFR, whereas calcidiol levels and serum phosphate levels did not. Overall, PTH levels were above normal in 34.9 % of patients. This proportion increased from 19.4 % in G1 category patients, to 33.7 % in G2 category patients and 56.6 % in G3-G5 category patients (p < 0.001). In multivariate analysis, eGFR and calcidiol levels were the main independent determinants of serum PTH. The mean FGF23 levels were 69.9 (54.6-96.2) relative units (RU)/ml, and 33.2 % of patients had FGF23 levels above 85.5 RU/ml (18.4 % in G1 category patients, 30.0 % in G2 category patients, and 59.2 % in G3-G5 category patients; p < 0.001). In multivariate analysis, eGFR was the main predictor of FGF23 levels. Increased phosphate levels were present in 0.7 % of the whole sample: 0 % in G1 category patients, 0.3 % in G2 category patients, and 2.8 % in G3-G5 category patients (p = 0.011). Almost 90 % of patients had calcidiol insufficiency without significant differences among the different degrees of eGFR. In conclusion, in patients with coronary artery disease there is a large prevalence of increased FGF23 and PTH levels. These findings have an independent relationship with decreased eGFR, and are evident at an eGFR of 60-89 ml/min/1.73 m(2). Then, mild decreases in eGFR must be taken in consideration by the clinician because they are associated with progressive abnormalities of mineral metabolism.

Impact of isolated hepatitis C virus (HCV) core-specific antibody detection and viral RNA amplification among HCV-seronegative dialysis patients at risk for infection.

Amplification of hepatitis C virus (HCV) RNA from blood detected occult HCV infections in 30.9% of 210 HCV-seronegative dialysis patients with abnormal liver enzyme levels that had evaded standard HCV testing practices. Isolated HCV core-specific antibody detection identified three additional anti-HCV screening-negative patients lacking HCV RNA amplification in blood who were considered potentially infectious. Together, these findings may affect management of the dialysis setting.

Cortisol levels are associated with mortality risk in hemodialysis patients.

BACKGROUND: End-stage renal disease (ESRD) conveys high mortality risk by complex mechanisms not fully elucidated but possibly linked to hormonal abnormalities, including cortisol. Whereas a high serum cortisol level has recently been linked with increased mortality in the general population, there is scarce information on the clinical associates and prognostic value of cortisol levels in ESRD. PATIENTS AND METHODS: Prospective study of prevalent hemodialysis patients (n = 75), mostly non-diabetic (76%), where cortisol levels were assessed and patients were afterwards followed for a median of 20 (interquartile range (IQR) 8 - 31) months. RESULTS: Cortisol levels were negatively correlated with plasma sodium (Rho = -0.26. p < 0.025) and positively correlated with C-reactive protein (CRP; Rho = 0.26, p = 0.027). The association with CRP remained independent of multiple confounders. Baseline cortisol levels of those who died were higher than of those who survived (19.8 ± 6.9 vs. 15.3 ± 5.7 mcg/dL, p = 0.0083). Kaplan-Meier analysis showed that patients with cortisol levels within the highest tertile (≥ 18 mcg/dL) were at increased risk of death. Cortisol was associated with risk of death both in crude and adjusted Cox proportional hazards models (HR 1.09 (1.021 - 1.167) p = 0.011; and 1.16 (1.027 - 1.309), p = 0.01, respectively)). CONCLUSIONS: High serum concentrations of cortisol were associated with a state of inflammation and independently identified a subgroup of chronic hemodialysis patients at a high mortality risk.

Individualization of dialysate calcium concentration according to baseline pre-dialysis serum calcium.

BACKGROUND: A positive calcium balance may contribute to vascular calcification, while a negative balance increases iPTH. We explored the impact of different dialysate calcium concentrations on bone and mineral metabolism parameters according to pre-dialysis serum calcium levels. RESULTS: Fifty-six hemodialysis patients were dialyzed with 3.0 or 2.5 mEq/l dialysate [calcium] in a crossover study of two weeks. Bone mineral metabolites were measured prior to and following the hemodialysis session. A 3.0 mEq/l dialysate [calcium] increased more post-dialysis total calcium and ionized calcium than 2.5 mEq/l dialysate [calcium]. The mildest dialysis-induced changes in calcium and PTH were observed in patients with pre-dialysis serum calcium <8.75 mg/dl dialyzed with 2.5 mEq/l dialysate [calcium] and in patients with pre-dialysis serum calcium >9.15 mg/dl dialyzed with 3.0 mEq/l calcium dialysate. CONCLUSION: In conclusion, the individualization of dialysate calcium concentration according to baseline pre-dialysis serum calcium may prevent major excursions in post-dialysis serum calcium and iPTH levels. SHORT SUMMARY: High calcium dialysate may increase serum calcium in hemodialysis patients, while low dialysate calcium may increase PTH. Individualization of dialysate calcium according to predialysis serum calcium levels may prevent or decrease unwanted excursions of both serum calcium and PTH.

Displacing the Burden: A Review of Protein-Bound Uremic Toxin Clearance Strategies in Chronic Kidney Disease.

Uremic toxins (UTs), particularly protein-bound uremic toxins (PBUTs), accumulate in chronic kidney disease (CKD) patients, causing significant health complications like uremic syndrome, cardiovascular disease, and immune dysfunction. The binding of PBUTs to plasma proteins such as albumin presents a formidable challenge for clearance, as conventional dialysis is often insufficient. With advancements in the classification and understanding of UTs, spearheaded by the European Uremic Toxins (EUTox) working group, over 120 molecules have been identified, prompting the development of alternative therapeutic strategies. Innovations such as online hemodiafiltration aim to enhance the removal process, while novel adsorptive therapies offer a means to address the high affinity of PBUTs to plasma proteins. Furthermore, the exploration of molecular displacers, designed to increase the free fraction of PBUTs, represents a cutting-edge approach to facilitate their dialytic clearance. Despite these advancements, the clinical application of displacers requires more research to confirm their efficacy and safety. The pursuit of such innovative treatments is crucial for improving the management of uremic toxicity and the overall prognosis of CKD patients, emphasizing the need for ongoing research and clinical trials.

Correction of hypocalcemia allows optimal recruitment of FGF-23-dependent phosphaturic mechanisms in acute hyperphosphatemia post-phosphate enema.

Both parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) are phosphaturic hormones. These hormones should increase in response to phosphate excess. However, they also regulate serum calcium; PTH increases serum calcium concentration and FGF23 suppresses renal production of calcitriol, favoring hypocalcemia. We report the case of an 83-year-old woman with hyperphosphatemia and hypocalcemia resulting from phosphate-containing enemas. PTH and calcitriol increased in response to hypocalcemia, and FGF23 increased in response to hyperphosphatemia. Unexpectedly, peak FGF23 did not coincide with peak serum phosphate. Rather, peak FG23 was observed only after severe hypocalcemia was partially corrected with exogenous calcium administration, even though serum phosphate had been already decreasing for 32 h. Correction of severe hypocalcemia was thus associated with peak FGF23 values and with a precipitous decrease in PTH. Peak FGF23 was followed by an accelerated decrease in serum phosphate and significant phosphaturia. This clinical report is consistent with experimental data in rats showing a blunted FGF23 response to high phosphate in the presence of severe hypocalcemia. Thus, complementary experimental and clinical data suggest that partial correction of severe hypocalcemia is required for optimal FGF23-mediated phosphaturia, which takes place despite correction of PTH levels. We believe this the first human report suggesting blunting of the FGF23 response to high phosphate by severe hypocalcemia.

Vitamin D, Cellular Senescence and Chronic Kidney Diseases: What Is Missing in the Equation?

As life expectancy increases in many countries, the prevalence of age-related diseases also rises. Among these conditions, chronic kidney disease is predicted to become the second cause of death in some countries before the end of the century. An important problem with kidney diseases is the lack of biomarkers to detect early damage or to predict the progression to renal failure. In addition, current treatments only retard kidney disease progression, and better tools are needed. Preclinical research has shown the involvement of the activation of cellular senescence-related mechanisms in natural aging and kidney injury. Intensive research is searching for novel treatments for kidney diseases as well as for anti-aging therapies. In this sense, many experimental shreds of evidence support that treatment with vitamin D or its analogs can exert pleiotropic protective effects in kidney injury. Moreover, vitamin D deficiency has been described in patients with kidney diseases. Here, we review recent evidence about the relationship between vitamin D and kidney diseases, explaining the underlying mechanisms of the effect of vitamin D actions, with particular attention to the modulation of cellular senescence mechanisms.

Recommendations of the Spanish Society of Nephrology for the management of mineral and bone metabolism disorders in patients with chronic kidney disease: 2021 (SEN-MM).

As in 2011, when the Spanish Society of Nephrology (SEN) published the Spanish adaptation to the Kidney Disease: Improving Global Outcomes (KDIGO) universal Guideline on Chronic Kidney Disease-Mineral and Bone Disorder (CKD-MBD), this document contains an update and an adaptation of the 2017 KDIGO guidelines to our setting. In this field, as in many other areas of nephrology, it has been impossible to irrefutably answer many questions, which remain pending. However, there is no doubt that the close relationship between the CKD-MBD/cardiovascular disease/morbidity and mortality complex and new randomised clinical trials in some areas and the development of new drugs have yielded significant advances in this field and created the need for this update. We would therefore highlight the slight divergences that we propose in the ideal objectives for biochemical abnormalities in the CKD-MBD complex compared to the KDIGO suggestions (for example, in relation to parathyroid hormone or phosphate), the role of native vitamin D and analogues in the control of secondary hyperparathyroidism and the contribution of new phosphate binders and calcimimetics. Attention should also be drawn to the adoption of important new developments in the diagnosis of bone abnormalities in patients with kidney disease and to the need to be more proactive in treating them. In any event, the current speed at which innovations are taking place, while perhaps slower than we might like, globally drives the need for more frequent updates (for example, through Nefrología al día).