Questioning the Safety of Calcidiol in Hemodialysis Patients.

BACKGROUND: Epidemiological studies have suggested a survival benefit for hemodialysis patients on paricalcitol or calcitriol, but nutritional vitamin D supplementation of patients already on vitamin D receptor (VDR) activators is controversial. METHODS: This observational retrospective cohort study was conducted with prospectively collected data from all consecutive patients with chronic kidney disease (CKD) who underwent hemodialysis under routine clinical practice conditions for two years. RESULTS: Of the 129 patients, 89 were treated with calcidiol, paricalcitol, and/or calcitriol. The patients with any vitamin D formulation had higher serum concentrations of 25-hydroxy vitamin D and fibroblast growth factor-23 and tended to have higher mortality rates (42% vs. 25%, p = 0.07). On subgroup analysis, any calcidiol treatment or calcidiol combined with paricalcitol associated with significantly higher mortality rates than no treatment (47% and 62.5%, p = 0.043 and 0.008, respectively). The association between calcidiol/paricalcitol treatment and elevated mortality remained significant after adjusting for age, sex, diabetes, C-reactive protein, and hemodialysis vintage. Any calcidiol and calcidiol/paricalcitol treatment exhibited a dose-response relationship with mortality (p for trend: 0.002 and 0.005, respectively). CONCLUSIONS: These data draw attention to the hitherto unexplored safety of calcidiol supplementation in patients on hemodialysis, especially in those already on vitamin D. Until clinical trials demonstrate the safety and efficacy of this approach, caution should be exercised when prescribing these patients ≥0.5 calcidiol mg/month.

Nutrients Turned into Toxins: Microbiota Modulation of Nutrient Properties in Chronic Kidney Disease.

In chronic kidney disease (CKD), accumulation of uremic toxins is associated with an increased risk of death. Some uremic toxins are ingested with the diet, such as phosphate and star fruit-derived caramboxin. Others result from nutrient processing by gut microbiota, yielding precursors of uremic toxins or uremic toxins themselves. These nutrients include l-carnitine, choline/phosphatidylcholine, tryptophan and tyrosine, which are also sold over-the-counter as nutritional supplements. Physicians and patients alike should be aware that, in CKD patients, the use of these supplements may lead to potentially toxic effects. Unfortunately, most patients with CKD are not aware of their condition. Some of the dietary components may modify the gut microbiota, increasing the number of bacteria that process them to yield uremic toxins, such as trimethylamine N-Oxide (TMAO), p-cresyl sulfate, indoxyl sulfate and indole-3 acetic acid. Circulating levels of nutrient-derived uremic toxins are associated to increased risk of death and cardiovascular disease and there is evidence that this association may be causal. Future developments may include maneuvers to modify gut processing or absorption of these nutrients or derivatives to improve CKD patient outcomes.

Design and rationale of a multicentre, randomised, double-blind, placebo-controlled clinical trial to evaluate the effect of vitamin D on ventricular remodelling in patients with anterior myocardial infarction: the VITamin D in Acute Myocardial Infarction (VITDAMI) trial.

INTRODUCTION: Decreased plasma vitamin D (VD) levels are linked to cardiovascular damage. However, clinical trials have not demonstrated a benefit of VD supplements on left ventricular (LV) remodelling. Anterior ST-elevation acute myocardial infarction (STEMI) is the best human model to study the effect of treatments on LV remodelling. We present a proof-of-concept study that aims to investigate whether VD improves LV remodelling in patients with anterior STEMI. METHODS AND ANALYSIS: The VITamin D in Acute Myocardial Infarction (VITDAMI) trial is a multicentre, randomised, double-blind, placebo-controlled trial. 144 patients with anterior STEMI will be assigned to receive calcifediol 0.266 mg capsules (Hidroferol SGC)/15 days or placebo on a 2:1 basis during 12 months. PRIMARY OBJECTIVE: to evaluate the effect of calcifediol on LV remodelling defined as an increase in LV end-diastolic volume ≥10% (MRI). SECONDARY OBJECTIVES: change in LV end-diastolic and end-systolic volumes, ejection fraction, LV mass, diastolic function, sphericity index and size of fibrotic area; endothelial function; plasma levels of aminoterminal fragment of B-type natriuretic peptide, galectin-3 and monocyte chemoattractant protein-1; levels of calcidiol (VD metabolite) and other components of mineral metabolism (fibroblast growth factor-23 (FGF-23), the soluble form of its receptor klotho, parathormone and phosphate). Differences in the effect of VD will be investigated according to the plasma levels of FGF-23 and klotho. Treatment safety and tolerability will be assessed. This is the first study to evaluate the effect of VD on cardiac remodelling in patients with STEMI. ETHICS AND DISSEMINATION: This trial has been approved by the corresponding Institutional Review Board (IRB) and National Competent Authority (Agencia Española de Medicamentos y Productos Sanitarios (AEMPS)). It will be conducted in accordance with good clinical practice (International Council for Harmonisation of Technical Requirements for Pharmaceuticals for Human Use - Good Clinical Practice (ICH-GCP)) requirements, ethical principles of the Declaration of Helsinki and national laws. The results will be submitted to indexed medical journals and national and international meetings. TRIAL REGISTRATION NUMBER: NCT02548364; Pre-results.

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.

Uso del sevelamer en la enfermedad renal crónica. Más allá del control del fósforo / Using sevelamer in chronic kidney disease. Beyond phosphorus control

El sevelamer es un captor no cálcico de fósforo que se utiliza en la ERC avanzada y en diálisis para el control de la hiperfosforemia. Varios estudios experimentales, observacionales y ensayos clínicos han mostrado que el sevelamer tiene efectos pleiotrópicos, más allá del control de la hiperfosforemia, incluyendo acciones sobre la inflamación, el estrés oxidativo, el perfil lipídico y la aterogénesis, la calcificación vascular, la disfunción endotelial y la disminución de diversas toxinas urémicas, todo lo cual sería la base biológica de su efecto global sobre la morbilidad y la mortalidad cardiovascular en pacientes con enfermedad renal crónica. En esta revisión, se hace énfasis en estas acciones pleiotrópicas del sevelamer y su impacto en la salud cardiovascular, con la experiencia publicada después de más de 10 años de experiencia clínica (AU)

Sevelamer is a calcium-free phosphate binder used in advanced chronic kidney disease (CKD) and in dialysis to control hyperphosphatemia. Several experimental and observational studies and clinical trials have shown that sevelamer has pleiotropic effects that go beyond controlling hyperphosphatemia; these pleiotropic effects include acting on inflammation, oxidative stress, lipid profile and atherogenesis, vascular calcification, endothelial dysfunction and decreasing various uremic toxins. All of these represent the biological basis for the global effect of sevelamer on cardiovascular morbidity and mortality in patients with CKD. In this review, we emphasis these pleiotropic actions of sevelamer and their impact on cardiovascular health, with the experience published after more than 10 years of clinical experience (AU)

Estudio REFOS: eficacia y seguridad del carbonato de lantano en la práctica clínica en España / REFOS study: Efficacy and safety of Lanthanum Carbonate in clinical practice in Spain

El carbonato de lantano es un potente captor de fósforo que en ensayos clínicos ha mostrado eficacia y seguridad para el manejo de la hiperfosforemia, aunque existen pocos datos en la práctica clínica habitual. El objetivo del estudio fue evaluar, en la práctica clínica habitual, su eficacia y seguridad en pacientes en diálisis. Se recogieron, retrospectivamente, datos de 15 meses de seguimiento, correspondientes a los 3 meses previos al inicio del tratamiento con carbonato de lantano y 12 meses después del inicio. Los datos incluían valores séricos de calcio, fósforo, fosfatasa alcalina, PTH, enzimas hepáticas y hemograma, así como la dosis diaria prescrita de carbonato de lantano, la medicación concomitante, el cumplimiento terapéutico y los eventos adversos. Se incluyeron 674 pacientes, de los cuales completaron el estudio 522. Los abandonos se debieron en mayor medida a trastornos gastrointestinales (26 %) e hipofosfatemia (19 %). El fósforo sérico disminuyó de 6,4 ± 1,7 mg/dl (inicio) a 4,9 ± 1,4 mg/dl (12 meses) (p < 0,001). Al final del seguimiento el 47 % se encontraba dentro del rango de fósforo deseado (3,5-5 mg/dl). No hubo variaciones significativas en el resto de los parámetros. Dosis inicial de carbonato de lantano: 1900 mg/día, y dosis final: 2300 mg/día. Las variables que se asociaron de forma independiente con la fosforemia final fueron el fósforo sérico basal y el cumplimiento terapéutico. Respecto a la seguridad, se observaron 238 efectos adversos leves o moderados que ocurrieron en 117 pacientes, estando el 88 % relacionado con alteraciones gastrointestinales. En conclusión, el carbonato de lantano reduce los valores séricos de fósforo en pacientes en diálisis con un buen perfil de seguridad y aceptable adherencia a este, siendo los trastornos gastrointestinales el efecto adverso más frecuente (AU)

Lanthanum carbonate is a powerful phosphate binder that has shown efficacy and safety in clinical trials for hyperphosphataemia management, although there are few data in regular clinical practice. The study's objective was to evaluate, in regular clinical practice, its efficacy and safety in patients on dialysis. We retrospectively collected data from 15 months of monitoring, corresponding to 3 months prior to the start of treatment with lanthanum carbonate until 12 months after the start. Results included values of serum calcium, phosphorus, alkaline phosphatase, iPTH, hepatic enzymes and haemogram, as well as the daily-prescribed dose of lanthanum carbonate, the concomitant medication, treatment compliance and adverse events. 647 patients were included of which 522 completed the study. Abandonment, for the most part, was due to gastrointestinal disorders (26%) and hypophosphatemia (19%). Serum phosphorus decreased from 6.4 ± 1.7mg/dl (start) to 4.9 ± 1.4mg/dl (12 months) (P<.001). At the end of the monitoring period, 47% were within the desired phosphorus range (3.5-5mg/dl). There were no significant variations in the remaining parameters. Initial dose of lanthanum carbonate: 1900mg/day; and end dose: 2300mg/day. The variables independently associated with phosphataemia were baseline serum phosphorus and treatment compliance. In relation to safety, we observed 238 slight or moderate adverse effects in 117 patients, with 88% linked to gastrointestinal abnormalities. In conclusion, lanthanum carbonate reduces the serum phosphorus values in patients on dialysis with a good safety profile and acceptable adherence to that profile, with gastrointestinal disorders being the most frequent adverse effect (AU)

Next-generation phosphate binders: focus on iron-based binders.

Phosphate excess is associated with increased mortality in patients with chronic kidney disease (CKD) and has recently been linked to accelerated aging. Oral phosphate binders are prescribed to patients with CKD to prevent absorption of dietary phosphate. Currently available binders have been associated with impaired outcomes (calcium-based binders) or are expensive (non-calcium-based binders). Iron-based phosphate binders represent a new class of phosphate binders. Four iron-based phosphate binders have undergone testing in clinical trials. The development of fermagate and SBR759 is currently on hold due to suboptimal and adverse effect profiles in at least some clinical trials. Ferric citrate and sucroferric oxyhydroxide (PA21) are at different stages of application for regulatory approval after being found safe and efficacious in decreasing serum phosphate. Iron from ferric citrate is more readily absorbed than that from sucroferric oxyhydroxide. Sucroferric oxyhydroxide was launched in the USA in 2014 for the treatment of hyperphosphatemia in adult dialysis patients. Ferric citrate may be more suited for chronic treatment of hyperphosphatemia in CKD patients requiring iron supplements but its use may have to be limited in time because of potential for iron overload in patients not needing iron or not receiving erythropoiesis-stimulating agents. In contrast, sucroferric oxyhydroxide may be more suited for hyperphosphatemic CKD patients not requiring iron supplements.

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.

High prevalence of winter 25-hydroxyvitamin D deficiency despite supplementation according to guidelines for hemodialysis patients.

BACKGROUND: There are seasonal variations in serum 25-hydroxyvitamin D (25OHD) levels related to sun exposure. Recent guidelines suggest a target serum 25OHD level >30 ng/ml in chronic kidney disease patients. However, vitamin D supplementation dosing and monitoring regimens are not well established in hemodialysis patients. The aim of this study was to assess the interplay between season and 25OHD supplementation according to guidelines on 25OHD levels in hemodialysis patients. METHODS: We retrospectively reviewed data collected prospectively over 12 months in 32 stable hemodialysis patients receiving 25OHD supplements (mean dose 30,600 IU/month) under routine clinical care following the Spanish Society of Nephrology guidelines. RESULTS: Higher serum 25OHD was observed during the summer, peaking in June and August. Despite a trend towards a higher 25OHD dose in winter the prevalence of 25OHD deficiency was still >40 % in winter. Furthermore, despite a higher dose of calcium-based phosphate binders, there was a trend toward lower serum calcium in winter. Season, together with residual diuresis and dry weight, was a significant independent contributor to a multivariate lineal regression model that explained 25 % of serum 25OHD variability, while a 25OHD dose did not contribute significantly in this 25OHD-supplemented population. CONCLUSION: Winter vitamin D deficiency is prevalent in hemodialysis patients despite supplementation with 25OHD according to clinical guidelines. More intensive monitoring or pre-emptive winter dose increases should be evaluated to achieve guideline targets.

Lanthanum carbonate reduces FGF23 in chronic kidney disease Stage 3 patients.

BACKGROUND: In chronic kidney disease (CKD) patients, the ability to excrete a phosphate load is impaired. Compensatory increase in parathyroid hormone (PTH) and fibroblast growth factor 23 (FGF23) promote phosphaturia. Serum FGF23 concentration is considered an early biomarker of excess phosphate load and high levels of FGF23 have been associated with increased mortality. In the present study, we have evaluated the changes in plasma FGF23 after treatment with the phosphate binder lanthanum carbonate in patients with CKD-3 and a normal serum phosphate concentration. METHODS: Eighteen Caucasian CKD Stage 3a/3b patients with serum phosphate <4.5 mg/dL were recruited in a prospective longitudinal open-label study. Patients received a 4-week period of standardized phosphorus-restricted diet containing 0.8 g/Kg/day protein. Thereafter, the same diet was maintained and patients received lanthanum carbonate (750 mg with the three main meals) for 4 weeks. RESULTS: No significant changes were observed in serum phosphate, however, lanthanum carbonate significantly decreased urinary excretion of phosphate and fractional excretion of phosphate (P < 0.004). This was accompanied by a significant decrease in carboxyterminal FGF23 (median percent change from baseline -21.8% (interquartile range -4.5, -30%), P = 0.025). No changes were observed in PTH. CONCLUSIONS: In conclusion, lanthanum carbonate reduced phosphate load, as assessed by urinary phosphate excretion, and also reduced plasma FGF23 in CKD-3 patients. This occurs in the presence of unchanged normal serum phosphate levels.

Recomendaciones de la Sociedad Española de Nefrología para el manejo de las alteraciones del metabolismo óseo-mineral en los pacientes con enfermedad renal crónica (SEN.-MM) / No disponible

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