Chronic renal failure is associated with increased tissue deposition of lanthanum after 28-day oral administration

Associations between urinary rare Earth elements with renal function: Findings from a cross-sectional study in Guangxi, China

BACKGROUND

With increased applications of rare earth elements (REEs) across various industries, evaluating the relationship between REEs exposure and potential health effects has become a public concern. In vivo experiments have established that REEs impact renal function. However, relevant epidemiological evidence on this relationship remains scarce. The objective of this study is to examine the impact of exposure to REEs on renal function.

METHODS

In this cross-sectional study, 1052 participants were recruited from Guangxi, China. We measured urinary concentrations of 12 REEs using an inductively coupled plasma-mass spectrometer (ICP-MS). Multiple linear regression models were developed to explore the relationship between a single REEs exposure and the estimated glomerular filtration rate (eGFR), a marker of renal function. Weighted quantile sum (WQS) regression and Bayesian kernel machine regression (BKMR) were used to examine the combined effects of REE co-exposure on eGFR.

RESULTS

In the multiple linear regression analysis, increasing the concentrations of lanthanum (La, β: 8.22, 95% CI: 5.67-10.77), cerium (Ce, β:6.61, 95% CI: 3.80-9.43), praseodymium (Pr, β: 8.46, 95% CI: 5.85-11.07), neodymium (Nd, β:8.75, 95% CI: 6.10-11.41), and dysprosium (Dy, β:7.38, 95% CI: 4.85-9.91) significantly increased the eGFR. In the WQS regression model, the WQS index was significantly associated with eGFR (β: 4.03, 95% CI: 2.46-5.60), with Pr having the strongest correlation with eGFR. Similar results were obtained in the BKMR model. Additionally, interactions between Pr and La, and Pr and Nd were observed.

CONCLUSIONS

Co-exposure to REEs is positively associated with elevated eGFR. Pr is likely to have the most significant influence on increased eGFRs and this might be exacerbated when interacting with La and Nd. Mixed exposure to low doses of REEs had a protective effect on renal function, which can provide some evidence for the exposure threshold of REEs in the environment.

TRIAL REGISTRATION

The study has been approved by the Guangxi Medical University Medical Ethics Committee (#20170206-1), and all participants provided written informed consent.

Long-term safety of lanthanum carbonate in the real word: a 19-year disproportionality analysis from the FDA Adverse Event Reporting System

BACKGROUND

Lanthanum carbonate is widely used to manage serum phosphate and calcium levels in end-stage kidney disease (ESKD) patients, yet comprehensive long-term safety data are lacking. This study leverages the FDA Adverse Event Reporting System (FAERS) to assess the extended safety profile of lanthanum carbonate.

RESEARCH DESIGN AND METHODS

We analyzed FAERS data (2004-2022) to study the association between lanthanum carbonate and adverse events (AEs). Using MedDRA v25.0, we identified risk signals through System Organ Classes (SOCs) and Preferred Terms (PTs). Disproportionality analyzes quantified lanthanum carbonate-associated AE signals.

RESULTS

Among 3,284 reports, 2,466 were primary suspected AEs linked to lanthanum carbonate. Males reported AEs more frequently than females. Patients aged over 64 represented the majority. Median onset time for lanthanum carbonate-related AEs was 146 days. Gastrointestinal disorders were prevalent. We identified 16 new signals, including stress, abnormal hepatic function, cholelithiasis, bile duct stone, gastric cancer, and adenocarcinoma gastric. Stress was notable, particularly in male patients over 65 and those with lower weight.

CONCLUSIONS

This study affirms lanthanum carbonate's long-term safety for reducing elevated blood phosphorus levels. While gastrointestinal disorders were common, attention must focus on emerging AEs, particularly stress, especially in elderly patients.

The efficacy and safety of cuttlebone for lowering serum phosphate in patients with end-stage renal disease: a meta-analysis of randomized controlled trials

Background: The efficacy of cuttlebone for treating hyperphosphatemia in patients with end-stage renal disease and its safety remained unclear. Methods: Randomized controlled trials comparing the efficacy of cuttlebone with conventional interventions were retrieved from MEDLINE, EMBASE, Cochrane Library, Airiti Library, and other major Chinese databases until 1 February 2023. The primary outcome was circulating phosphate concentration, while secondary outcomes included circulating calcium and intact parathyroid hormone levels, calcium-phosphorus product, and treatment-related side-effects. Results: Analysis of nine studies published between 2000 and 2019 including 726 participants showed a lower circulating phosphate concentration in the cuttlebone group than in controls [mean difference (MD) = -0.23, 95% CI: -0.39 to -0.06, p = 0.006, I2 = 94%, 726 patients] and a dose-dependent effect of cuttlebone against hyperphosphatemia. Therapeutic benefits were noted after both short-term (1-2 months) and long-term (3-6 months) treatments. Besides, patients receiving hemodialysis showed a better response to cuttlebone than those receiving peritoneal dialysis. There was no difference in circulating calcium level (mean difference = 0.03, 95% CI: -0.01 to 0.07, p = 0.17, I2 = 34%, 654 patients), while patients receiving cuttlebone showed lower circulating iPTH level and calcium-phosphorus product (MD = -43.63, 95% CI: -74.1 to -13.16, p = 0.005, I2 = 76%, 654 patients), (MD = -0.38, 95% CI: -0.38 to -0.01, p = 0.04, I2 = 83%, 520 patients). No difference in the risks of constipation, gastrointestinal discomfort, and elevated blood calcium was noted between the two groups. Conclusion: Compared with conventional phosphate-binding agents, cuttlebone more efficiently suppressed hyperphosphatemia with a dose-dependent effect. The limited number of included studies warrants further clinical investigations to verify our findings. Systematic Review Registration: https://www.crd.york.ac.uk/prospero/, identifier CRD42023396300.

U-Shaped Relationship of Rare Earth Element Lanthanum and Oral Cancer Risk: A Propensity Score-Based Study in the Southeast of China

As an important rare earth element (REE) extensively applied to industry, agriculture, and medicine, lanthanum (La) has attracted a host of health concerns. This study aimed to explore the relationship between La exposure and the risk of developing oral cancer through a case-control study with a large sample size. Serum La levels of 430 oral cancer patients and 1,118 healthy controls were detected by inductively coupled plasma mass spectrometry (ICP-MS). The association of La level with the risk of oral cancer was assessed in two ways: (1) as a continuous scale based on restricted cubic splines (RCS); (2) as a priori defined centile categories using multivariate logistic regression model, based on propensity score matching (PSM) and inverse probability of treatment weighting (IPTW). The RCS revealed a non-linear U-shaped relationship between serum La and oral cancer risk. Serum La deficiency or excess was associated with an increased risk of oral cancer. When the La level was analyzed as a categorical variable, a similar U-shaped association was observed. Of note, compared to those with La concentrations of 0.243–0.341 μg/L (reference quantiles, 41st−60th), the risk was increased in those with the lower or higher quantiles (0.132–0.242 μg/L vs. 0.243–0.341 μg/L: OR = 1.80, 95%CI: 1.07–3.02; 0.342–0.497 μg/L vs. 0.243–0.341 μg/L: OR = 2.30, 95%CI: 1.38–3.84). The results were generally consistent with the PSM and IPTW analyses. This preliminary study provides strong evidence that there was a U-shaped relationship between serum La levels and oral cancer risk. Much additional work is warranted to confirm our findings.

A Two-Generation Reproductive Toxicity Study of Lanthanum Nitrate in SD Rats

In order to evaluate the effects of lanthanum nitrate on the development of the parent, offspring, and the third generation of Sprague-Dawley (SD) rats, a two-generation reproductive toxicity experiment, was conducted. Two hundred and forty specific pathogen-free (SPF) healthy SD rats were randomly divided into the control group, low-, medium-, and high-dose group, with 30 male and 30 female rats in each group. The rats in each group were given 0 mg/kg, 10.0 mg/kg, 30.0 mg/kg, and 90.0 mg/kg lanthanum nitrate by gavage, respectively. There was no statistically significant difference between the weight gain and food intake of rats in each group. High-dose lanthanum nitrate had no effect on rat implantation and no embryo toxicity. The absolute and relative liver weights of F1a and F1b male rats in the high-dose group were significantly decreased. The absolute liver and spleen weight of F1b female rats in the high-dose group decreased significantly, but the relative weight did not change significantly. Histopathological examination results showed that there were no significant differences in the effects of different doses of lanthanum nitrate on the uterus, ovaries, oviduct, testes and epididymis, and liver of SD rats. Under the experimental conditions, 90.0 mg/kg lanthanum nitrate had an effect on the liver weight of the SD rats, but there was no liver toxicity. The no visible harmful effect level (NOAEL) of lanthanum nitrate on SD rats' reproduction toxicity is 90 mg/kg.

Past, Present, and Future of Phosphate Management

Cardiovascular (CV) disease (CVD) accounts for >50% of deaths with known causes in patients on dialysis. Elevated serum phosphorus levels are an important nontraditional risk factor for bone mineral disease and CVD in patients with chronic kidney disease (CKD). Given that phosphorus concentrations drive other disorders associated with increased CV risk (e.g., endothelial dysfunction, vascular calcification, fibroblast growth factor-23, parathyroid hormone), phosphate is a logical target to improve CV health. Phosphate binders are the only pharmacologic treatment approved for hyperphosphatemia. Although their safety has improved since inception, the mechanism of action leads to characteristics that make ingestion difficult and unpleasant; large pill size, objectionable taste, and multiple pills required for each meal and snack make phosphate binders a burden. Side effects, especially those affecting the gastrointestinal (GI) system, are common with binders, often leading to treatment discontinuation. The presence of “hidden” phosphates in processed foods and certain medications makes phosphate management even more challenging. Owing to these significant issues, most patients on dialysis are not consistently achieving and maintaining target phosphorus concentrations of <5.5 mg/dl, let alone more normal levels of <4.5 mg/dl, indicating novel approaches to improve phosphate management and CV health are needed. Several new nonbinder therapies that target intestinal phosphate absorption pathways have been developed. These include EOS789, which acts on the transcellular pathway, and tenapanor, which targets the dominant paracellular pathway. As observational evidence has established a strong association between phosphorus concentration and clinical outcomes, such as mortality, phosphate is an important target for improving the health of patients with CKD and end-stage kidney disease (ESKD).

In Search of an Efficient Complexing Agent for Oxalates and Phosphates: A Quantum Chemical Study

Limiting gastrointestinal oxalate absorption is a promising approach to reduce urinary oxalate excretion in patients with idiopathic and enteric hyperoxaluria. Phosphate binders, that inhibit gastrointestinal absorption of dietary phosphate by the formation of easily excretable insoluble complexes, are commonly used as a treatment for hyperphosphatemia in patients with end-stage renal disease. Several of these commercially available phosphate binders also have affinity for oxalate. In this work, a series of metallic cations (Li⁺, Na⁺, Mg²⁺, Ca²⁺, Fe²⁺, Cu²⁺, Zn²⁺, Al³⁺, Fe³⁺ and La³⁺) is investigated on their binding affinity to phosphate and oxalate on one side and anionic species that could be used to administer the cationic species to the body on the other, e.g., acetate, carbonate, chloride, citrate, formate, hydroxide and sulphate. Through quantum chemical calculations, the aim is to understand the competition between the different complexes and propose possible new and more efficient phosphate and oxalate binders.

Cell and molecular toxicity of lanthanum nanoparticles: are there possible risks to humans?

Lanthanum nanoparticles are widely used in industry, agriculture, and biomedicine. Over 900 kg of lanthanum is annually released into the environment only in Europe, 50 times higher than the metals, mercury, and cadmium's environmental spread. Human health risk associated with long-term exposure to the abundant lanthanum nanoparticles is a concerning environmental issue. Due to lanthanum's ability to disrupt the main biological barriers and interrupt various cells' hemostasis, they seem to cause severe disruptions to various tissues. This review opens a new perspective regarding the cellular and molecular interaction of nanosized and ionic lanthanum with the possible toxicity on the nervous system and other tissues that would show lanthanum nanoparticles' potential danger to follow in toxicological science.

[Unexpected deposits in the upper gastrointestinal tract : When medical history matters]

In order to regulate their phosphate uptake, patients with end-stage renal disease rely on phosphate binders such as lanthanum carbonate (LC). The earliest histopathological reports of this rare entity in the gastrointestinal mucosa were described and published in 2015.We present a case of an 80-year-old patient with LC gastro-enteropathy. Histopathologically it can mimic other drug-induced depositions and even infectious or neoplastic entities. Evaluation of the patient's medical and especially drug history is essential to obtain the appropriate diagnosis. We present an overview of the clinical presentation and histological differential diagnosis of LC.

Deposition patterns of iatrogenic lanthanum and gadolinium in the human body depend on delivered chemical binding forms

BACKGROUND

Recently, gadolinium from linear GBCAs has been reported to deposit in various regions of the body. Besides gadolinium, other lanthanides are used in medical care. In the current study, we investigated deposition of lanthanum in two patients who received lanthanum carbonate as a phosphate binder due to chronic kidney injury and compared it to additionally found Gd deposition.

METHODS

Tissue specimens of two patients with long-term application of lanthanum carbonate as well as possible GBCA application were investigated. Spatial distribution of gadolinium and lanthanum was determined by quantitative laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) imaging of tissue sections. The deposition of gadolinium and lanthanum in different organs was compared, and the ratio of Gd concentration to La concentration (Gd-to-La-ratio) was investigated on an individual pixel base within the images.

RESULTS

Deposition of Gd and La was found in all investigated tissues of both patients. Gd and La exhibited high spatial correlation for all samples, with the main deposition being located in the middle coat (tunica media) of blood vessels. The Gd-to-La-ratio was similar in the tissues investigated (between 8 ± 4 (mean ± standard deviation) and 10 ± 2), except for the thyroid vasculature and surrounding tissue (90 ± 17) as well as the cerebellum (270 ± 18). Here, the ratio was significantly increased towards higher Gd concentration.

CONCLUSION

The results of this study demonstrate long-term deposition of La and comparable localization of additionally found Gd in various tissues of the body. La deposition was relatively low, considering the total administered amount of lanthanum carbonate of up to 11.5 kg, indicating a low absorption and/or high excretion of lanthanum. However, the total amount of deposited La is significant and raises questions about possible adverse side effects. The ratio-approach allows for the usage of the additionally generated Gd data, without detailed knowledge about possible GBCA applications. The significantly decreased Gd-to-La-ratio in the brain might be explained by the lanthanum being released and taken up as free La³⁺ ion in the stomach that impedes a crossing of the blood-brain-barrier while the intravenously injected GBCAs might dechelate first when they have already crossed the blood-brain-barrier.

Review of the diagnosis of gastrointestinal lanthanum deposition

Lanthanum carbonate is used for treatment of hyperphosphatemia mostly in patients with chronic renal failure. Although lanthanum carbonate is safe, recently, lanthanum deposition in the gastrointestinal mucosa of patients has been reported in the literature. This review provides an overview of gastroduodenal lanthanum deposition and focuses on disease’s endoscopic, radiological, and histological features, prevalence, and outcome, by reviewing relevant clinical studies, case reports, and basic research findings, to better understand the endoscopic manifestation of gastrointestinal lanthanum deposition. The possible relationship between gastric lanthanum deposition pattern and gastric mucosal atrophy is also illustrated; in patients without gastric mucosal atrophy, gastric lanthanum deposition appears as diffuse white lesions in the posterior wall and lesser curvature of the gastric body. In the gastric mucosa with atrophy, lanthanum-related lesions likely appear as annular or granular whitish lesions. Moreover, these white lesions are probably more frequently observed in the lower part of the stomach, where intestinal metaplasia begins.

Effects of in utero exposure to lanthanum on neurological behavior in rat offspring

The increasing use of rare-earth elements in various fields has raised concern from public heath perspective regarding their accumulation in human body. Long-term exposure to lanthanum, one of the frequently used rare-earth elements in biomedicine and agriculture, has been previously shown to exert neurotoxicity during development in rats; however, the effects of short-term exposure to lanthanum during gestation on neurobehavioral development in rat offspring is still not clear. The purpose of this study is to investigate the effects of intrauterine exposure to lanthanum on neurobehavioral development in rat offspring. Dams were orally exposed to 0, 2, 20, & 60 mg/kg BW of lanthanum nitrate from gestation day 7 to day 16. Morris water maze test, hindlimb strength test, nociceptive perception test, and grip strength test were conducted during postnatal day 61 to 66 in rat offspring. Blood lanthanum concentration and plasma neurotransmitters were measured after sacrifice. The results showed that intrauterine exposure to lanthanum nitrate significantly impaired memory and spatial learning in Morris water maze test. Lanthanum treatment dose-dependently increased blood lanthanum concentration in dams and pups. Lanthanum treatment significantly decreased hindlimb and grip strength and increased delay time in nociceptive response. Plasma neurotransmitter results showed that lanthanum treatment significantly decreased the level of acetylcholine and serotonin while increased the level of glutamate in rat offspring. These results suggest that short-term in utero exposure to lanthanum has potential adverse effects on neurodevelopment in rat offspring.

[Studies of the Various Chronic Kidney Failure Rat Models and Hemodialysis Mini-pig Model for the Evaluation of Anti-hyperphosphatemia Drugs]

Animal models of chronic kidney failure (CKF) have been developed for the pharmacodynamic evaluation of various phosphate binders that are used clinically to treat hyperphosphatemia in patients with chronic kidney disease. However, these models represent different disease states and severities, depending on the experimental conditions and are not clearly defined for pharmacological evaluation. In addition, experimental models have not yet been established for artificial dialysis. The purpose of this study was to confirm the utility of the various rat models of CKF and the mini-pig model of hemodialysis as models of hyperphosphatemia for pharmacodynamic evaluation. Various rat models of pre-dialysis CKF (oral adenine dosing, 5/6 resection, and ligation nephrectomy model) were evaluated through determinations of serum and urinary parameters (osmolality, creatinine, and phosphorus), pathological observations of kidney, and the phosphorus-absorbing properties of lanthanum carbonate (La) formulations. The rat and mini-pig models were compared based on each evaluation index. In the oral adenine dosing model, serum phosphorus increased markedly and the area under the serum phosphorus concentration-time curve (phosphorus AUC) decreased in a dose-dependent manner with the administration of La formulations. In contrast, a significant decrease in serum phosphorus AUC, a prolongation of the dialysis interval, and an improvement in dialysis efficiency were observed after administration of La formulations to the mini-pig hemodialysis model. Furthermore, the results of bioequivalence studies between two La formulations (Fosrenol and SW670, a generic formulation) suggested that the rat and mini-pig models are useful and precise as pre-dialysis and dialysis models, respectively.

Strategies for Phosphate Control in Patients With CKD

Hyperphosphatemia is a common complication in patients with chronic kidney disease (CKD), particularly in those requiring renal replacement therapy. The importance of controlling serum phosphate has long been recognized based on observational epidemiological studies that linked increased phosphate levels to adverse outcomes and higher mortality risk. Experimental data further supported the role of phosphate in the development of bone and cardiovascular diseases. Recent advances in our understanding of the mechanisms involved in phosphate homeostasis have made it clear that the serum phosphate concentration depends on a complex interplay among the kidneys, intestinal tract, and bone, and is tightly regulated by a complex endocrine system. Moreover, the source of dietary phosphate and the use of phosphate-based additives in industrialized foods are additional factors that are of particular importance in CKD. Not surprisingly, the management of hyperphosphatemia is difficult, and, despite a multifaceted approach, it remains unsuccessful in many patients. An additional issue is the fact that the supposedly beneficial effect of phosphate lowering on hard clinical outcomes in interventional trials is a matter of ongoing debate. In this review, we discuss currently available treatment approaches for controlling hyperphosphatemia, including dietary phosphate restriction, reduction of intestinal phosphate absorption, phosphate removal by dialysis, and management of renal osteodystrophy, with particular focus on practical challenges and limitations, and on potential benefits and harms.

Gadolinium chloride promotes proliferation of HEK293 human embryonic kidney cells by activating EGFR/PI3K/Akt and MAPK pathways

Prolonged exposure to gadolinium-based contrast agents has been reported to trigger nephrogenic systemic fibrosis in end stage renal disease patients. However, the exact molecular mechanisms are not fully understood, and no effective therapy is available to date. In the present study, we report that gadolinium chloride (Gd³⁺) concentration- and time-dependently promoted the proliferation of HEK293 human embryonic kidney cells by increasing DNA synthesis. Gd³⁺ treatment increased the protein levels of phosphorylated Akt and MAPKs. Inhibition of Akt and ERK by pharmacological inhibitors abolished the increased proliferation and cell cycle progression. Furthermore, Gd³⁺ activated EGFR signaling possibly by enhancing EGFR clustering on the cell membrane. Inhibition of EGFR by gefitinib blocked Gd³⁺-induced proliferation. Gd³⁺ exposure also upregulated the mRNA levels of TGFβ-1, TGFβR1, TNFα, TIMP-1 and integrin αV, β1 which could also be attenuated by the inhibition of Akt and ERK signaling. Our study provides new clues for the etiological role of Gd³⁺ in the pathogenesis of nephrogenic systemic fibrosis, and suggests the inhibition of EGFR/Akt/ERK signaling as a potential treatment strategy.

The Control of Hyperphosphatemia in Chronic Kidney Disease: Which Phosphate Binder?

Hyperphosphatemia is currently regarded as a key mortality risk predictor in late CKD stages and especially in patients on dialysis. Fortunately, the armatorium to effectively treat hyperphosphatemia in end-stage renal disease has grown in recent years, and we gained an improved understanding of potential benefits and harms of specific compounds. Most interestingly, novel insights into the pathophysiology of calcium and phosphate handling, especially, the discovery of the phosphatonin FGF23, suggest a more complex assessment of phosphate balance especially in predialysis stages is warranted. This assessment should probably include measurements of fractional phosphate excretion and phosphatonin levels to objectively judge and effectively correct phosphate overload, however, clinical data on calcium and phosphate metabolism in CKD stages 3 – 4 are still scarce. This overview will both discuss aspects of pathophysiology of phosphate regulation and current and future clinical treatement approaches.

Endothelin A receptor blocker and calcimimetic in the adenine rat model of chronic renal insufficiency

BACKGROUND

We studied whether endothelin receptor antagonist and calcimimetic treatments influence renal damage and kidney renin-angiotensin (RA) components in adenine-induced chronic renal insufficiency (CRI).

METHODS

Male Wistar rats (n = 80) were divided into 5 groups for 12 weeks: control (n = 12), 0.3% adenine (Ade; n = 20), Ade + 50 mg/kg/day sitaxentan (n = 16), Ade + 20 mg/kg/day cinacalcet (n = 16), and Ade + sitaxentan + cinacalcet (n = 16). Blood pressure (BP) was measured using tail-cuff, kidney histology was examined, and RA components measured using RT-qPCR.

RESULTS

Adenine caused tubulointerstitial damage with severe CRI, anemia, hyperphosphatemia, 1.8-fold increase in urinary calcium excretion, and 3.5-fold and 18-fold increases in plasma creatinine and PTH, respectively. Sitaxentan alleviated tubular atrophy, while sitaxentan + cinacalcet combination reduced interstitial inflammation, tubular dilatation and atrophy in adenine-rats. Adenine diet did not influence kidney angiotensin converting enzyme (ACE) and AT₄ receptor mRNA, but reduced mRNA of renin, AT_1a, AT₂, (pro)renin receptor and Mas to 40-60%, and suppressed ACE2 to 6% of that in controls. Sitaxentan reduced BP by 8 mmHg, creatinine, urea, and phosphate concentrations by 16-24%, and PTH by 42%. Cinacalcet did not influence BP or creatinine, but reduced PTH by 84%, and increased hemoglobin by 28% in adenine-rats. The treatments further reduced renin mRNA by 40%, while combined treatment normalized plasma PTH, urinary calcium, and increased ACE2 mRNA 2.5-fold versus the Ade group (p < 0.001).

CONCLUSIONS

In adenine-induced interstitial nephritis, sitaxentan improved renal function and tubular atrophy. Sitaxentan and cinacalcet reduced kidney renin mRNA by 40%, while their combination alleviated tubulointerstitial damage and urinary calcium loss, and increased kidney tissue ACE2 mRNA.

A Combined Deposition of Lanthanum and β2-Microglobulin-Related Amyloid in the Gastroduodenal Mucosa of Hemodialysis-Dependent Patients: An Immunohistochemical, Electron Microscopic, and Energy Dispersive X-Ray Spectrometric Analysis

Lanthanum carbonate (LC) is a new type of phosphate adsorbent used to treat patients with hyperphosphatemia caused by chronic kidney diseases. Recent studies have pointed out that lanthanum deposition can be found in the cytoplasm of histiocytes in the gastroduodenal mucosa of these patients. On the other hand, it is well known that patients on long-term hemodialysis can develop deposition of β2-microglobulin-related amyloid (Aβ2M) mainly around joints. However, involvement of the gastrointestinal tract by hemodialysis-associated amyloidosis has been thought to be rare, and therefore only Aβ2M, if any, has been reported to accumulate in the vascular walls of the submucosa and muscularis propria. Thus, in contrast to AA amyloid, biopsy from gastrointestinal mucosa has long been considered to have little significance in detecting amyloid. We present unusual histologic findings on biopsy specimens taken from the gastroduodenal mucosa of 7 hemodialysis-dependent patients taking LC for more than a year. These findings were due to a combined deposition of lanthanum and β2-microglobulin-related amyloid in the cytoplasm of histiocytes. The deposition of amyloid was confirmed by conventional histochemistry, immunohistochemistry, and transmission electron microscopy, and that of lanthanum by transmission electron microscopy and scanning electron microscopy/energy dispersive X-ray spectrometry. This is the first report of such a peculiar combined deposition of lanthanum and amyloid in the gastroduodenal mucosa of hemodialysis patients. Although the exact mechanism of combination and pathogenesis is unclear, we believe that histologic examination of the gastrointestinal mucosa should be considered in the careful follow-up and observation of hemodialysis patients taking LC.

The evaluation of lanthanum trapped prussian blue as a phosphate binding agent with reduced bone uptake

Lanthanum trapped Prussian blue is developed as a two-process-independent phosphate binder with the main feature of reduced lanthanum accumulation.

Preclinical Pharmacokinetics, Pharmacodynamics and Safety of Sucroferric Oxyhydroxide

Sucroferric oxyhydroxide (VELPHORO^®) is a polynuclear iron-based phosphate binder recently approved for the treatment of hyperphosphataemia in patients with chronic kidney disease (CKD). As a number of the available phosphate binders do not provide the optimal combination of good efficacy, adequate tolerability and low pill burden, sucroferric oxyhydroxide constitutes a promising alternative. Among the attributes of an ideal phosphate binder is minimal absorption and, hence, low risk of systemic toxicity. Accordingly, the iron-releasing properties and absorption, distribution, metabolism and excretion (ADME) profile of sucroferric oxyhydroxide, as well as the possibility of iron accumulation and toxicity, were investigated in a series of preclinical studies. The effect of sucroferric oxyhydroxide on the progression of vascular calcification was also investigated. Sucroferric oxyhydroxide exhibited a high phosphate-binding capacity and low iron-releasing properties across the physiological pH range found in the gastrointestinal tract. In the ADME studies, uptake of ⁵⁹Fe-radiolabelled sucroferric oxyhydroxide was low in rats and dogs (<1% from a 50 mg Fe/kg bodyweight dose), with the majority of absorbed iron located in red blood cells. Long-term (up to 2 years) administration of sucroferric oxyhydroxide in rats and dogs was associated with modest increases in tissue iron levels and no iron toxicity. Moreoever, in uraemic rats, sucroferric oxyhydroxide was associated with reduced progression of vascular calcification compared with calcium carbonate. In conclusion, sucroferric oxyhydroxide offers a new option for the treatment of hyperphosphataemia, with a high phosphate-binding capacity, minimal iron release, and low potential for iron accumulation and toxicity.

Advances in pharmacotherapy for hyperphosphatemia in renal disease

INTRODUCTION

Hyperphosphatemia in chronic kidney disease (CKD) is considered as an independent risk factor for surrogate clinical end points like vascular calcification (VC) and bone disease, or hard clinical outcomes like cardiovascular events. Various treatment options are available for phosphate removal or reduction. Calcium-based phosphate binders (CBB) with their possible positive calcium balance became culprits for progressive VC and increased mortality risk. Non-calcium-based binders (NCBB) treatment allowed a comparable control of hyperphosphatemia with a lower risk of hypercalcemia and a slower progression of VC. Recent data have shown a 22% risk reduction in all-cause mortality with NCBB compared to CBB treatment. The appropriate timing of phosphate binder initiation in CKD patients is still unclear. Recent reports in patients with CKD stages 3b-4 showed increased VC progression when actively treated compared to placebo and a positive calcium, but no negative phosphate balance.

AREAS COVERED

This review discusses the advantages and disadvantages of the pharmacological options to treat hyperphosphatemia.

EXPERT OPINION

The use of phosphate binders is essential in preventing morbidity and mortality in dialysis patients. The choice of phosphate binder takes into account CKD stage, the presence of other components of CKD-mineral and bone disorders, concomitant therapies and drug side-effect profile.

Peculiar histiocytic lesions with massive lanthanum deposition in dialysis patients treated with lanthanum carbonate

Pathologic lesions caused by lanthanum carbonate (LC), a recently developed phosphate-binding agent, have not been recorded. A peculiar gastroduodenal histiocytic lesion associated with a mucosal lanthanum overload was reported. Our routine gastrointestinal biopsy series included 6 cases with heavy lanthanum burden in the gastroduodenal mucosa. In addition to routine histopathologic examinations, a series of immunohistochemical analysis and electron microscopic examinations associated with x-ray diffraction and elemental analysis were performed. Six cases, 3 of male and 3 of female individuals with ages from 59 to 69 years, were all patients of end-stage renal diseases managed under dialysis and treated with LC for >21 months. Endoscopic examinations demonstrated gastric erosions in 3, gastric polyps in 2, and duodenal ulcer in 1. In the mucosal layer, there were numerous non-Langerhans cell histiocytes, stained with CD68 but not S100 protein, engulfing a large amount of mineral-like materials. An electron microscopic and elemental analysis revealed a similar distribution of lanthanum and phosphorus in the histiocytes. Long-standing LC administration can cause massive mucosal accumulation of lanthanum in the tissue histiocytes associated with several forms of gastroduodenal lesions. A long-standing outcome is not clear at present; hence, careful follow-up studies of these patients may be needed.

Possibility of lanthanum absorption in the stomach

Lanthanum carbonate (LC) is an orally administered phosphate binder. Its absorption is generally thought to be minimal. We report here the case of an 81-year-old woman who underwent subtotal gastrectomy for gastric cancer after receiving hemodialysis for 1 year and taking LC for 7 months. Lanthanum phosphate compounds were found histologically in the gastric mucosa and a regional lymph node and confirmed by scanning and transmission electron microscopy–energy-dispersive X-ray spectroscopy. These findings suggest that lanthanum is absorbed in the stomach and transported via lymph flow. This observation could prove helpful in future investigation of lanthanum disposition.

Molecular mechanism of oxidative damage of lung in mice following exposure to lanthanum chloride

Exposure to lanthanoids (Ln) elicits an adverse response such as oxidative injury of lung in animals and human. The molecular targets of Ln remain unclear. In the present study, the function and signal pathway of nuclear factor erythroid 2 related factor 2 (Nrf2) in LaCl3 -induced oxidative stress in mouse lung were investigated. Mice were exposed to 2, 5, and 10 mg/kg body weight by nasal administration for 6 consecutive months. With increased doses, La was markedly accumulated and promoted the reactive oxygen species (ROS) production in the lung, which in turn resulted in peroxidation of lipids, proteins and DNA, and severe pulmonary damages. Furthermore, LaCl3 exposure could significantly increase levels of Nrf2, heme oxygenase 1 (HO-1) and glutamate-cysteine ligase catalytic subunit (GCLC) expressions in the LaCl3 -exposed lung. These findings imply that the induction of Nrf2 expression is an adaptive intracellular response to LaCl3 -induced oxidative stress in mouse lung, and that Nrf2 may regulate the LaCl3 -induced pulmonary damages.

Extensive lanthanum deposition in the gastric mucosa: the first histopathological report

Lanthanum carbonate is one of the new phosphate binders used for the treatment of hyperphosphatemia in patients with chronic kidney disease. It is poorly absorbed from the gastrointestinal tract, forms insoluble complexes within the lumen, and prevents the absorption of dietary phosphate. A 63-year-old female with a 7-year history of peritoneal dialysis, who was treated with lanthanum carbonate for four years, underwent endoscopic submucosal dissection for intramucosal gastric cancer. Resected specimens showed massive accumulation of macrophages containing fine, granular, brown material in the lamina propria. This was confirmed as lanthanum deposition by scanning electron microscopy with energy dispersive x-ray spectroscopy. Although lanthanum may be poorly absorbed, increased tissue accumulation of lanthanum, particularly in the liver and bone, has been reported in animals with chronic kidney disease. This report indicates enhanced gastrointestinal absorption of lanthanum in some patients or conditions, although its clinical significance awaits further studies.

Lanthanum chloride impairs spatial memory through ERK/MSK1 signaling pathway of hippocampus in rats

Rare earth elements (REEs) are used in many fields for their diverse physical and chemical properties. Surveys have shown that REEs can impair learning and memory in children and cause neurobehavioral defects in animals. However, the mechanism underlying these impairments has not yet been completely elucidated. Lanthanum (La) is often selected to study the effects of REEs. The aim of this study was to investigate the spatial memory impairments induced by lanthanum chloride (LaCl3) and the probable underlying mechanism. Wistar rats were exposed to LaCl3 in drinking water at 0 % (control, 0 mM), 0.25 % (18 mM), 0.50 % (36 mM), and 1.00 % (72 mM) from birth to 2 months after weaning. LaCl3 considerably impaired the spatial learning and memory of rats in the Morris water maze test, damaged the synaptic ultrastructure and downregulated the expression of p-MEK1/2, p-ERK1/2, p-MSK1, p-CREB, c-FOS and BDNF in the hippocampus. These results indicate that LaCl3 exposure impairs the spatial learning and memory of rats, which may be attributed to disruption of the synaptic ultrastructure and inhibition of the ERK/MSK1 signaling pathway in the hippocampus.

Environmental fate and ecotoxicity of lanthanides: are they a uniform group beyond chemistry?

Lanthanides are a chemically uniform group of metals (La-Lu) that, together with yttrium (Y) and scandium (Sc), form the group of rare earth elements (REEs). Because of their many applications (e.g., agriculture, medicine, motor industry), their global production has increased exponentially in the last decades and their biogeochemical cycles are being disrupted by human uses (e.g., gadolinium anomalies in freshwater and tap water, REEs enrichment of soils as a consequence of agricultural practices). However, ecotoxicological effects and mechanism of action of these elements are still poorly understood. In particular, there is no consensus as to lanthanides showing a coherent and predictable pattern of (eco)toxicity in the same way as their atomic properties. For aquatic organisms, contradictory conclusions on this issue can be found in the bibliography. This review shows that the variable composition of culture media used in ecotoxicology, and the associated differences in lanthanide's speciation, are the most likely cause for such discrepancies. In particular, the formation of insoluble species in some highly complexing media likely leads to changes in the soluble concentration of lanthanide during some tests; with the potential for a generalized underestimation of their toxicity at the present state of knowledge. For terrestrial organisms, suitable studies to establish trends in lanthanides' toxicity are practically nonexistent; with most research focusing on the effects of REE mixtures. Molecular level studies to elucidate the mechanisms of action of lanthanides are essentially limited to La, pointing to the need for further research to identify common mechanisms of action or modes of action across lanthanides. Overall, agreement on the correct procedures to follow to obtain reliable and comparable data for individual lanthanide is the first action to take in order to arrive at a reliable risk assessment for this group of elements in both aquatic and terrestrial systems.

Lanthanum carbonate for the control of hyperphosphatemia in chronic renal failure patients: a new oral powder formulation - safety, efficacy, and patient adherence

Chronic kidney disease (CKD) is associated with very high mortality rates, mainly of cardiovascular origin. The retention of phosphate (P) and increased fibroblast growth factor-23 levels are common, even at early stages of CKD, due to disturbances in normal P homeostasis. Later, hyperphosphatemia appears, which has also been strongly associated with high mortality rates linked to P-mediated cardiovascular and procalcifying effects. Treatment guidelines for these patients continue to be poorly implemented, at least partially due to the lack of adherence to a P-restricted diet and P-binder therapy. Calcium-free P binders, such as lanthanum carbonate, have been associated with a decreased progression of vascular calcification, rendering them an important therapeutic alternative for these high cardiovascular risk CKD patients. Lanthanum carbonate has typically been available as chewable tablets, and the new presentation as an oral powder may provide a useful alternative in the therapeutic armamentarium. This powder is a tasteless, odorless, and colorless semisolid compound miscible with food. In a recent study in healthy individuals, the safety and efficacy of this novel form were evaluated, and it was concluded that it is well tolerated and pharmacodynamically equivalent to the chewable form. In the long run, individualization of preferences and treatments seems an achievable goal prior to final demonstration of improvements in hard outcomes in wide clinical trials in CKD patients.

Efficacy and safety of lanthanum carbonate on chronic kidney disease-mineral and bone disorder in dialysis patients: a systematic review

BACKGROUND

Chronic kidney disease-mineral and bone disorder (CKD-MBD) is a common complication in CKD patients, particularly in those with end-stage renal disease that requires dialysis. Lanthanum carbonate (LC) is a potent, non-aluminum, non-calcium phosphate binder. This systematic review evaluates the efficacy and safety of LC in CKD-MBD treatment for maintenance-dialysis patients.

METHODS

A systematic review and meta-analysis on randomized controlled trials (RCTs) and quasi-RCTs was performed to assess the efficacy and safety of LC in maintenance hemodialysis or peritoneal dialysis patients. Analysis was performed using the statistical software Review Manager 5.1.

RESULTS

Sixteen RCTs involving 3789 patients were identified and retained for this review. No statistical difference was found in all-cause mortality. The limited number of trials was insufficient to show the superiority of LC over other treatments in lowering vascular calcification or cardiovascular events and in improving bone morphology, bone metabolism, or bone turn-over parameters. LC decreased the serum phosphorus level and calcium × phosphate product (Ca × P) as compared to placebo. LC, calcium carbonate (CC), and sevelamer hydrochloride (SH) were comparable in terms of controlling the serum phosphorus, Ca × P product, and intact parathyroid hormone (iPTH) levels. However, LC resulted in a lower serum calcium level and a higher bone-specific alkaline phosphatase level compared with CC. LC had higher total cholesterol and low-density lipoprotein (LDL) cholesterol levels compared with SH. LC-treated patients appeared to have a higher rate of vomiting and lower risk of hypercalcemia, diarrhea, intradialytic hypotension, cramps or myalgia, and abdominal pain. Meta-analysis showed no significant difference in the incidence of other side effects. Accumulation of LC in blood and bone was below toxic levels.

CONCLUSIONS

LC has high efficacy in lowering serum phosphorus and iPTH levels without increasing the serum calcium. Current evidence does not show a higher rate of adverse effects for LC compared with other treatments, except for a higher incidence of vomiting. Moreover, LC accumulation in blood and bone was below toxic levels. Well-designed studies should be conducted to evaluate the long-term effects of LC.

Nephroprotective effects of Isaria felina in rats with adenine-induced chronic renal failure

Objective

Chronic renal failure (CRF) is a progressive, life-threatening condition with limited treatment options. Cordyceps sinensis is a fungus that has nephroprotective effects, and Isaria felina (IF) is a fungus isolated from C. sinensis fruiting bodies. We evaluated IF efficacy using an adenine-induced CRF animal model.

Methods

Forty male Sprague-Dawley rats were divided into normal control (n = 8) and adenine groups (n = 32; 100 mg/kg for 30 days). The adenine group was subdivided into a model control group (n = 7), a positive control group (200 mg/kg Jinshuibao capsule (JSB; n = 8), and two IF groups (200 mg/kg, n = 8; 100 mg/kg, n = 8). After treatment for 30 days, animals were narcotized and abdominal aortic blood was analysed. Kidney functions were evaluated.

Key findings

Higher serum creatinine, blood urea nitrogen and uric acid levels, and lower creatinine clearance was observed in the model control group compared with JSB and IF groups (P &lt; 0.05). Red blood cell count, haemoglobin and haematocrit levels in the 200 mg/kg IF group were higher than in the model control group (P &lt; 0.05). Transforming growth factor-β1 mRNA expression in the model control group was higher than the normal control and 200 mg/kg IF groups (P &lt; 0.05). Epidermal growth factor mRNA in the model control group was lower than in the normal control and both IF-treated groups (P &lt; 0.05). Structural renal damage was observed in all adenine-treated rats, but was less severe in the JSB and IF groups.

Conclusion

IF may reverse the damaged kidney functions-induced with adenine in rats.

Additional reduction in serum phosphorus levels by pulverized lanthanum carbonate chewable in hemodialysis patients

Lanthanum carbonate (LC) is one of the relatively new phosphate binders. The general LC dosage form is a chewable pharmaceutical preparation. This investigation was targeted to subjects who do not chew LC chewable preparations adequately, for the purpose of studying the clinical efficacy of changing to pulverized prescriptions, such as changes in serum phosphorus levels (P levels). The study took place at Minamisenju Hospital in October 2011, with 41 subjects on maintenance hemodialysis. We pulverized all of the LC chewable medicines of the LC insufficient mastication group (non-chewing: NC group, n = 18) using a crusher, and changed them to pulverized prescriptions. The testing period was set at 10 weeks. In the NC group, there was a significant lowering of P levels from 5.86 ± 1.31 mg/dL before pulverization of the LC chewable preparation (week 0) to 5.38 ± 1.26 mg/dL after 2 weeks of administration of the pulverized medication (P = 0.0310), 5.20 ± 1.25 mg/dL after 4 weeks (P = 0.0077), and 5.12 ± 1.34 mg/dL after 6 weeks (P = 0.0167). P levels in other patients than NC group showed no significant change. In this study, the P levels in the NC group was lowered significantly by changing the LC chewable to the pulverized prescription, and the residual LC images on the abdominal X-rays disappeared to the point where they could barely be confirmed.

Management of hyperphosphataemia in chronic kidney disease-challenges and solutions

Hyperphosphataemia is a clinical consequence of the advanced stages of chronic kidney disease (CKD). Considerable evidence points to a role of hyperphosphataemia in the pathogenesis of CKD-associated cardiovascular (CV) complications, including vascular calcification, and with increased all-cause and CV mortality. These observations place management of hyperphosphataemia at the centre of CKD treatment. Although our increased understanding of the physiological role of FGF-23 may provide a long-term alternative biomarker of phosphate load and underlying disease progression, regular determination of serum phosphate is currently the most frequently used parameter to evaluate phosphate load in clinical practice. This review considers the challenges physicians and patients face in trying to control hyperphosphataemia. Amongst these are the limitations of dietary phosphate restriction, giving rise to the need for phosphate binder therapy to maintain serum phosphate control. Once the decision to use phosphate binders has been made, considerations include the relative efficacy, different potential side effects and pill burden associated with various phosphate binders. Although a number of phosphate binders are available, adherence poses a major obstacle to effective treatment. This emphasizes that further improvements to phosphate binder therapy can be made. Evaluation of novel agents and their potential role in the clinic should continue.

Npt2b deletion attenuates hyperphosphatemia associated with CKD

The incidence of cardiovascular events and mortality strongly correlates with serum phosphate in individuals with CKD. The Npt2b transporter contributes to maintaining phosphate homeostasis in the setting of normal renal function, but its role in CKD-associated hyperphosphatemia is not well understood. Here, we used adenine to induce uremia in both Npt2b-deficient and wild-type mice. Compared with wild-type uremic mice, Npt2b-deficient uremic mice had significantly lower levels of serum phosphate and attenuation of FGF23. Treating Npt2b-deficient mice with the phosphate binder sevelamer carbonate further reduced serum phosphate levels. Uremic mice exhibited high turnover renal osteodystrophy; treatment with sevelamer significantly decreased the number of osteoclasts and the rate of mineral apposition in Npt2b-deficient mice, but sevelamer did not affect bone formation and rate of mineral apposition in wild-type mice. Taken together, these data suggest that targeting Npt2b in addition to using dietary phosphorus binders may be a therapeutic approach to modulate serum phosphate in CKD.

Vascular calcification in chronic kidney disease: Pathogenesis and clinical implication

Cardiovascular disease is the leading cause of death among patients with chronic kidney disease (CKD). Vascular calcification (VC) is one of the independent risk factors associated with cardiovascular disease and cardiovascular mortality in both the general population and CKD patients. Earlier evidence revealed substantially higher prevalence of VC in young adults on chronic hemodialysis compared to the general population in the same age range, indicating the influence of CKD-related risk factors on the development of VC. Pathogenesis of VC involves an active, highly organized cellular transformation of vascular smooth muscle cells to bone forming cells evidenced by the presence of bone matrix proteins in the calcified arterial wall. VC occurs in both the intima and the media of arterial wall with medial calcification being more prevalent in CKD. In addition to traditional cardiovascular risks, risk factors specific to CKD such as phosphate retention, excess of calcium, history of dialysis, active vitamin D therapy in high doses and deficiency of calcification inhibitors play important roles in promoting the development of VC. Non-contrast multi-slice computed tomography has often been used to detect coronary artery calcification. Simple plain radiographs of the lateral lumbar spine and pelvis can also detect VC in the abdominal aorta and femoral and iliac arteries. Currently, there is no specific therapy to reverse VC. Reduction of calcium load, lowering phosphate retention using non-calcium containing phosphate binders, and moderate doses of active vitamin D may attenuate progression. Parenteral sodium thiosulfate has also been shown to delay VC progression.

Lanthanum(III) impacts on metallothionein MTT1 and MTT2 from Tetrahymena thermophila

Metallothionein MTT1 and MTT2 from Tetrahymena thermophila are sulfydryl-rich proteins that can bind to and are inducible by heavy metals such as mercury, cadmium, zinc, and copper. However, little is known about the induction and binding of T. thermophila metallothionein by trivalent metals. In this study, we found that 10-80 μM La(3+) can promote Tetrahymena cells proliferation, and fluorescence spectrum analysis showed that La(3+) can enter T. thermophila cells. Real-time quantitative polymerase chain reaction showed La(3+) induced the expression of MTT1 and MTT2. Furthermore, Fluorescence analysis indicated La(3+) bind to MTT1 and MTT2. These results implied that La(3+) could interact with MTT1 and MTT2 via aspartic or glutamic acid oxygen atoms.

Sevelamer carbonate in the treatment of hyperphosphatemia in patients with chronic kidney disease on hemodialysis

Sevelamer carbonate is an anion exchange pharmaceutical, developed to improve on the performance of the non-absorbable, non-calcium, and metal-free phosphate binder sevelamer hydrochloride. Sevelamer carbonate is expected not to worsen metabolic acidosis, as previously reported during long-term treatment with sevelamer hydrochloride in hemodialysis (HD) patients. Carbonate is the alternate counterion to chloride on the sevelamer polymeric backbone, but the active poly(allylamine) responsible for phosphate (PO₄) binding remains unaltered. Therefore, sevelamer carbonate is expected to reduce elevated serum phosphorus level, similarly to sevelamer hydrochloride. Sevelamers are prescribed in uremic HD patients to control hyperphosphatemia, but the carbonate has also been proposed for the treatment of chronic kidney disease (CKD) non-dialysis patients. Although hyperphosphatemia is regarded as a main contributor to increased mortality in the HD population because of cardiovascular calcification, metabolic acidosis has also been advocated as a major player in the increased mortality in this population, by engendering malnutrition, negative nitrogen balance, and inflammation. This paper reviews the evidence showing that sevelamer carbonate is as good as sevelamer hydrochloride in terms of hyperphosphatemia control in CKD, but with a better outcome in serum bicarbonate balance.

Mineral and bone disorders in children with chronic kidney disease

As children with chronic kidney disease (CKD) have a long lifespan, optimal control of bone and mineral homeostasis is essential not only for the prevention of debilitating skeletal complications and for achieving adequate growth but also for preserving long-term cardiovascular health. As the growing skeleton is highly dynamic and at particular risk of deterioration, close control of bone and mineral homeostasis is required in children with CKD. However, assessment of bone disease is hampered by the limited validity of biochemical parameters-major controversy exists on key issues such as parathyroid hormone target ranges and the lack of useful imaging techniques. The role of newly discovered factors in bone and mineral homeostasis, such as fibroblast growth factor 23, is not yet established. Even though scientific evidence is limited in children with CKD, ergocalciferol or cholecalciferol supplementation and the use of calcium-free phosphate binders is recommended. The new drug cinacalcet is highly promising; however, pediatric experience is still limited to observational data and the effect of cinacalcet on longitudinal growth and pubertal development is unknown. Randomized, controlled trials are underway, including studies of cinacalcet pharmacokinetics and pharmacodynamics in infants.

Rare earth elements in the Rhine River, Germany: first case of anthropogenic lanthanum as a dissolved microcontaminant in the hydrosphere

The distribution of dissolved rare earth elements (REE) in the Rhine River, Germany, shows the anthropogenic gadolinium (Gd) microcontamination that is commonly observed in rivers in densely populated countries with a highly evolved health care system. However, the Rhine River also carries anomalously high concentrations of lanthanum (La), which produce very large positive La anomalies in normalized REE distribution patterns. These positive La anomalies first occur north of the City of Worms and then decrease in size downstream, but are still significant approximately 400 km downstream, close to the German-Dutch border. The strong La enrichment is of anthropogenic origin and can be traced back to effluent from a production plant for fluid catalytic cracking catalysts at Rhine river-km 447.4. This effluent is characterized by extremely high dissolved total REE and La concentrations of up to 52 mg/kg and 49 mg/kg, respectively. Such La concentrations are well-above those at which ecotoxicological effects have been observed. The Rhine River is the first case observed to date, where a river's dissolved REE inventory is affected and even dominated by anthropogenic La. Our results suggest that almost 1.5t of anthropogenic dissolved La is exported via the Rhine River into the North Sea per year. This reveals that the growing industrial use of REE (and other formerly "exotic" elements) results in their increasing release into the environment, and highlights the urgent need to determine their geogenic background concentrations in terrestrial surface waters.