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).

Anti-Spike antibodies three months after SARS-CoV-2 mRNA vaccine booster dose in patients on hemodialysis: the prospective SENCOVAC study

Introduction

Patients on hemodialysis are at high-risk for complications derived from coronavirus disease-19 (COVID-19). The present analysis evaluated the impact of a booster vaccine dose and breakthrough severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections on humoral immunity three months after the booster dose.

Methods

This is a multicentric and prospective study assessing IgG anti-Spike antibodies 6 and 9 months after initial SARS-CoV-2 vaccination in patients on hemodialysis that had also received a booster dose before the 6-month assessment (early booster) or between the 6- and 9-month assessments (late booster). The impact of breakthrough infections, type of vaccine, time from the booster and clinical variables were assessed.

Results

A total of 711 patients (67% male, 67 [20-89] years) were included. Of which, 545 (77%) received an early booster and the rest a late booster. At 6 months, 64 (9%) patients had negative anti-Spike antibody titers (3% of early booster and 29% of late booster patients, p = 0.001). At 9 months, 91% of patients with 6-month negative response had seroconverted and there were no differences in residual prevalence of negative humoral response between early and late booster patients (0.9% vs 0.6%, p = 0.693). During follow-up, 35 patients (5%) developed breakthrough SARS-CoV-2 infection. Antibody titers at 9 months were independently associated to mRNA-1273 booster (p = 0.001), lower time from booster (p = 0.043) and past breakthrough SARS-CoV-2 infection (p<0.001).

Conclusions

In hemodialysis patients, higher titers of anti-Spike antibodies at 9 months were associated to mRNA-1273 booster, lower time from booster and past breakthrough SARS-CoV-2 infection.

RICORS2040: the need for collaborative research in chronic kidney disease

Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is ‘solved’ by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020–2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true.

Distar Renal Tubular Acidosis (dRTA): Epidemiological, diagnostics, clinical follow-up and therapeutical issues. Nephrologists cohort survey outcome

BACKGROUND AND OBJECTIVES

dRTA is a genetic or acquired rare disease, characterized by an unability to excrete hydrogens (H+) into urine, hypobicarbonatemia, hyperchloremia, and frequently hypercalciuria and hypokalaemia. Genetic forms are usually diagnosed during the first months of life and its treatment is based on providing alkali supplements in order to prevent long term clinical consequences, particularly chronic kidney disease (described in some cohorts up to 82% of dRTA patients) and the associated bone disease. A 10 queries multi choice closed response survey was designed to know more about epidemiological, diagnostics, clinical management and therapeutical issues of this disease among Spanish nephrologists.

METHODS AND MATERIALS

This survey was delivered to the attendees to a scientific meeting on dRTA at the Spanish Nephrology Society congress in 2019. Surveys were collected at the end of this dRTA event. Results were analyzed by using a parametric statistical test, obtaining the percentage of each response for the 10 questions.

RESULTS

Among the survey responders, 44.4% and 37.7% did not visit any dRTA patient during the 1st and 3rd last year respectively. When having a suspicious diagnose, confirming genetic diagnostic test is only performed on the 13.3% of cases and pedigree studies only on 11.1%. Only a 26.6% confirms that metabolic control is excellent, good or very good. 69% of the responders believe that treatment compliance is not bad, bad or very bad.

CONCLUSIONS

This survey enhances the fact that dRTA is not a well known entity, satisfaction with metabolic control is poor and compliance is low. All these factors can lead to a higher severity of renal and bone diseases associated to dRTA.

Distar Renal Tubular Acidosis (dRTA): Epidemiological, diagnostics, clinical follow-up and therapeutical issues. Nephrologists cohort survey outcome

BACKGROUND AND OBJECTIVES

dRTA is a genetic or acquired rare disease, characterized by an unability to excrete hydrogens (H+) into urine, hypobicarbonatemia, hyperchloremia, and frequently hypercalciuria and hypokalaemia. Genetic forms are usually diagnosed during the first months of life and its treatment is based on providing alkali supplements in order to prevent long term clinical consequences, particularly chronic kidney disease (described in some cohorts up to 82% of dRTA patients) and the associated bone disease. A 10 queries multi choice closed response survey was designed to know more about epidemiological, diagnostics, clinical management and therapeutical issues of this disease among Spanish nephrologists.

MATERIALS AND METHODS

This survey was delivered to the attendees to a scientific meeting on dRTA at the Spanish Nephrology Society congress in 2019. Surveys were collected at the end of this dRTA event. Results were analyzed by using a parametric statistical test, obtaining the percentage of each response for the 10 questions.

RESULTS

Among the survey responders, 44.4% and 37.7% did not visit any dRTA patient during the 1st and 3rd last year respectively. When having a suspicious diagnose, confirming genetic diagnostic test is only performed on the 13.3% of cases and pedigree studies only on 11.1%. Only a 26.6% confirms that metabolic control is excellent, good or very good, and 69% of the responders believe that treatment compliance is not bad, bad or very bad.

CONCLUSIONS

This survey enhances the fact that dRTA is not a well known entity, satisfaction with metabolic control is poor and compliance is low. All these factors can lead to a higher severity of renal and bone diseases associated to dRTA.

Nebivolol, a β1-adrenergic blocker, protects from peritoneal membrane damage induced during peritoneal dialysis

Peritoneal dialysis (PD) is a form of renal replacement treatment, which employs the peritoneal membrane (PM) to eliminate toxins that cannot be removed by the kidney. The procedure itself, however, contributes to the loss of the PM ultrafiltration capacity (UFC), leading consequently to the technique malfunction. β-blockers have been considered deleterious for PM due to their association with loss of UFC and induction of fibrosis. Herein we analyzed the effects of Nebivolol, a new generation of β₁-blocker, on PM alterations induced by PD fluids (PDF).

In vitro: We found that mesothelial cells (MCs) express β₁-adrenergic receptor. MCs were treated with TGF-β to induce mesothelial-to-mesenchymal transition (MMT) and co-treated with Nebivolol. Nebivolol reversed the TGF-β effects, decreasing extracellular matrix synthesis, and improved the fibrinolytic capacity, decreasing plasminogen activator inhibitor-1 (PAI-1) and increasing tissue-type plasminogen activator (tPA) supernatant levels. Moreover, Nebivolol partially inhibited MMT and decreased vascular endothelial growth factor (VEGF) and IL-6 levels in supernatants.

In vivo: Twenty-one C57BL/6 mice were divided into 3 groups. Control group carried a catheter without PDF infusion. Study group received intraperitoneally PDF and oral Nebivolol during 30 days. PDF group received PDF alone. Nebivolol maintained the UFC and reduced PM thickness, MMT and angiogenesis promoted by PDF. It also improved the fibrinolytic capacity in PD effluents decreasing PAI-1 and IL-8 and increased tPA levels.

Conclusion: Nebivolol protects PM from PDF-induced damage, promoting anti-fibrotic, anti-angiogenic, anti-inflammatory and pro-fibrinolytic effects.

Differences between 2nd and 3rd generation seric parathormone determination methods on mortality in haemodialysis patients

Parathormone plays a key role in controlling mineral metabolism. PTH is considered a uremic toxin causing cardiovascular damage and cardiovascular mortality in dialysis patients. There are two different assays to measure PTH called 2nd generation or intact PTH (iPTH) and 3rd generation or bioPTH (PTHbio).

OBJECTIVE

To evaluate the differences in mortality of dialysis patients between both assays to measure PTH, as well as the possible prognostic role of the PTHbio/iPTH ratio.

METHODS

145 haemodialysis patients were included with 2-year monitoring including baseline laboratory test and annually thereafter.

RESULTS

21 patients died in the first year and 28 in the second. No correlation was found between PTH, PTHbio and PTHbio/iPTH ratio with mortality. Both PTH have a perfect correlation between them and correlate similarly with other molecules of the mineral metabolism. The extreme baseline values of PTH are those of higher mortality. In survival by iPTH intervals (according to guidelines and COSMOS study), a J curve is observed. When iPTH increases, the ratio decreases, possibly when increasing fragments no. 1-84. There is no greater prognostic approximation on mortality with PTHbio than PTHi. There was also no difference in mortality when progression ratio PTHbio/PTHi was analysed.

CONCLUSIONS

We didn't find any advantages to using bioPTH vs. PTHi as a marker of mortality. BioPTH limits of normality must be reevaluated because its relationship with iPTH is not consistent. Not knowing these limits affects its prognostic value.

Glomerulonefritis rápidamente progresiva asociada a endocarditis afebril y anca anti-proteinasa 3

La endocarditis asociada a ANCA anti-PR3 e insuficiencia renal plantea un dilema tanto en su diagnóstico como tratamiento. Para abordar una revisión de dicho tema, se presenta el caso de un paciente con glomerulonefritis rápidamente progresiva secundaria a endocarditis subaguda por Enterococcus faecalis y positividad para ANCA anti-PR3. El diagnóstico diferencial principal se establecería entre una afectación renal de una vasculitis asociada a ANCA no diagnosticada previamente vs una glomerulonefritis postinfecciosa secundaria a la endocarditis. En muchos casos es necesario disponer de una biopsia renal que esclarezca el diagnóstico, ya que una inmunofluorescencia negativa orientará hacia una vasculitis, mientras que una positividad para inmunocomplejos iría a favor de una glomerulonefritis postestreptocócica. El tratamiento a seguir es otro reto que se plantea en la coexistencia de insuficiencia renal aguda, endocarditis y ANCA anti-PR3 positivo. La positividad de ANCAs induce a valorar iniciar tratamiento con inmunosupresores, no obstante, en el lecho de una endocarditis puede resultar desaconsejado e incluso poner en riesgo la vida del paciente someterlo a un estado de inmunosupresión. Es, por tanto, controvertido el uso de inmunosupresión en combinación con antibioterapia en el proceso agudo en contraposición al uso de antibioterapia exclusivamente. En el actual artículo se recogen los 19 casos publicados en la literatura de endocarditis asociados a ANCA anti-PR3, así como el tratamiento que se realizó en cada uno de los casos y la evolución en la función renal de cada paciente, concluyendo, en general, una mejor recuperación de la función renal en los pacientes tratados con antibioterapia en exclusiva que en aquellos tratados con la combinación antibióticocorticoides. Sin embargo, dado el pequeño tamaño muestral, no se puede considerar significativa la diferencia entre ambos tratamientos.

Bisfenol (A) una toxina a tener en cuenta en el enfermo renal en hemodiálisis

Muchas toxinas urémicas son originadas como consecuencia del catabolismo proteico por la flora intestinal. El metabolismo de aminoácidos aromáticos origina residuos de tipo fenólico. De estas toxinas, la más estudiada es el p-cresol, que se asocia a la función renal y daño vascular. El Bisfenol A (BPA) es una molécula exógena de características semejantes a estas toxinas urémicas aromáticas. El BPA es un disruptor endocrino estrogénico que se encuentra en latas de conserva, botellas de plástico, resinas epoxi y en algunos dializadores. Esta molécula se acumula en pacientes que tienen deteriorada la función renal. Estudios observacionales han demostrado que una exposición a BPA está vinculada, entre otras muchas, a lesión renal y cardiovascular en los seres humanos; en estudios en animales se ha descrito un vínculo causal. Los riñones con función renal normal excretan rápidamente BPA, pero una excreción insuficiente en pacientes con ERC da lugar a la acumulación del BPA en el organismo.

Gut microbiota in chronic kidney disease

The intestinal microflora maintains a symbiotic relationship with the host under normal conditions, but its imbalance has recently been associated with several diseases. In chronic kidney disease (CKD), dysbiotic intestinal microflora has been reported with an increase in pathogenic flora compared to symbiotic flora. An enhanced permeability of the intestinal barrier, allowing the passage of endotoxins and other bacterial products to the blood, has also been shown in CKD. By fermenting undigested products that reach the colon, the intestinal microflora produce indoles, phenols and amines, among others, that are absorbed by the host, accumulate in CKD and have harmful effects on the body. These gut-derived uraemic toxins and the increased permeability of the intestinal barrier in CKD have been associated with increased inflammation and oxidative stress and have been involved in various CKD-related complications, including cardiovascular disease, anaemia, mineral metabolism disorders or the progression of CKD. The use of prebiotics, probiotics or synbiotics, among other approaches, could improve the dysbiosis and/or the increased permeability of the intestinal barrier in CKD. This article describes the situation of the intestinal microflora in CKD, the alteration of the intestinal barrier and its clinical consequences, the harmful effects of intestinal flora-derived uraemic toxins, and possible therapeutic options to improve this dysbiosis and reduce CKD-related complications.

Use of sevelamer in chronic kidney disease: beyond phosphorus control

Sevelamer is a non-calcium phosphate binder used in advanced chronic kidney disease (CKD) and in dialysis for hyperphosphataemia control. Several experimental, observational studies and clinical trials have shown that sevelamer has pleiotropic effects, beyond hyperphosphataemia control, including actions on inflammation, oxidative stress, lipid profile and atherogenesis, vascular calcification, endothelial dysfunction and the reduction of several uremic toxins. This is the biological basis for its global effect on cardiovascular morbidity and mortality in patients with chronic kidney disease. This review focuses on these pleiotropic actions of sevelamer and their impact on cardiovascular health, with the experience published after more than ten years of clinical expertise.

[Complementary artificial nutrition in kidney failure]

Denutrition of the uremic patient is a substantial contributing factor to the high rate of morbimortality. At the present time there are no resources which slow the catabolic situation conditioned by humoral or hormonal factors, but resources are available which act on the nutritional factors. The aim of this paper is to study the effect of additional administration of a complete enteral diet, but high in calories and in proteins, on the nutrition of dialysis patients. Six patients undergoing periodic hemodialysis and without metabolic illness were selected: 236 ml of the solution was administered orally on a daily basis for two months. They were studied statistically using the SIGMA Program, with application of the comparison of paired averages, the variations of anthropometric and analytical data and urea kinetics. The results revealed a significant body weight increase, from 58 to 60 kg, and of the tricipital fold from 10 to 12 cm: both variations were statistically significant (p < 0.01). There were no variations in the analytical data, or in the urea kinetics (the PCR was 0.8 g/kg/day and the Kt/V was 0.8). It is concluded that it significantly improves the nutritional state, there are no side effects and it does not detract from the efficacy of the dialysis. Therefore, and although the indication for which it was designed was for predialysis patients, we think that those under periodic hemodialysis--and, form the same reasons, acute kidney failure patients--might be areas for the use of this product.