In end-stage renal failure, does infection lead to elevated plasma aluminium and neurotoxicity? Implications for monitoring

Research Progress on Cognitive Frailty in Older Adults with Chronic Kidney Disease

BACKGROUND

As the medical challenges posed by the ageing population become increasingly severe, the proportion of older people among patients with chronic kidney disease (CKD) is increasing every year.

SUMMARY

The prevalence of frailty in patients with CKD is significantly higher than that in the general population, and older patients are also a high-risk group for frailty and cognitive impairment. Cognitive frailty, as an important subtype of frailty, is a syndrome characterised by cognitive dysfunction caused by physiological factors, excluding Alzheimer's disease and other types of dementia. It is characterised by the coexistence of physical frailty and cognitive impairment. Previous studies have mainly focused on cognitive impairment, and there is limited research on cognitive frailty, particularly in older patients with CKD.

KEY MESSAGES

This article provides a comprehensive review of the concept, epidemiology, screening methods, prevention, and treatment measures and possible pathogenesis of cognitive frailty in patients with CKD.

Dose-response relationships in aluminium toxicity in humans

INTRODUCTION

Aluminium exposure is associated with bone disease (an elevated bone content of aluminium and reduced bone formation on bone biopsy) and neurotoxicity (features of altered brain functions and/or typical spike and slow wave waveforms on electroencephalogram) in patients with elevated blood aluminium concentrations.

OBJECTIVES

To critically analyse the literature to determine the dose-toxicity relationships between aluminium exposure and related bone disease and aluminium neurotoxicity.

METHODS

A systematic review of the literature with collation and analysis of individual data of human cases of aluminium exposure was conducted between 1 January 1966 and 30 December 2020. Embase, MEDLINE (OVID MEDLINE), PubMed and TOXNET were searched with the following strategies: "Aluminium AND toxicity OR aluminium AND poisoning OR aluminium AND dialysis OR aluminium AND chronic renal failure OR aluminium AND intravenous" limited to "(human)". Inclusion criteria required individual data relating to aluminium exposure in humans. Papers in which features of aluminium toxicity and analytical confirmation of aluminium exposure could not be determined in individual patients were excluded.

RESULTS

Thirty-seven papers were identified, which included data on 179 individuals exposed to aluminium. The sources of aluminium exposure (median duration of exposure) were: dialysis fluid (48 months) in 110 cases; oral aluminium hydroxide (20 months) in 20 cases; plasma exchange (2 months) in 16 cases; infant formula feed (minimal duration of 2 weeks) in 14 cases; intravesical exposures (2 days) in 13 oncology patients and potable water exposure in six cases.

EXPOSURE TO DIALYSIS FLUID

Of the 110 patients exposed to dialysis fluid, 99 were adults and 11 children, who were analysed separated. Of the adults, 50 with aluminium neurotoxicity had a median aluminium concentration of 467 µg/L (IQR 230 - 752), 28 with aluminium bone disease had a median aluminium concentration of 142 µg/L (IQR 46-309) and 21 with asymptomatic aluminium overload had a median aluminium concentration of 35 µg/L (IQR 26-51). Median aluminium concentrations were significantly greater in patients with aluminium neurotoxicity compared to those with aluminium bone disease (p < 0.0001) or asymptomatic aluminium overload (p < 0.0001).

ORAL ALUMINIUM HYDROXIDE

Of the 20 cases, 11 were adults and nine were children. Of the 11 adults, eight with aluminium neurotoxicity had a median aluminium concentration of 682 µg/L (IQR 438-770) and three with aluminium bone disease had a median aluminium concentration of 100 µg/L (IQR 62-138) (p = 0.007). Of the nine children, five had aluminium neurotoxicity with a median aluminium concentration of 335 µg/L (IQR 229-601), one had aluminium bone disease and an aluminium concentration of 1030 µg/L and three had asymptomatic aluminium overload with a median aluminium concentration 98 µg/L (IQR 65-365).

PLASMA EXCHANGE

Three patients with stage 5 chronic kidney disease developed aluminium bone disease during plasma exchange; their median blood or serum aluminium concentration was 73 µg/L (IQR 59-81). Asymptomatic aluminium overload was reported in six patients receiving outpatient plasma exchange who had a median creatinine clearance of 71 mL/min (IQR 40-106) and a median aluminium concentration of 49 µg/L (IQR 34-116), and in seven intensive care patients with acute kidney injury whose median aluminium concentration was 30 µg/L (IQR 17-35); (p = 0.02).

INTRAVESICAL EXPOSURES

All 13 intravesical exposures developed aluminium neurotoxicity and had a median aluminium concentration of 157 µg/L (IQR 45-276).

POTABLE WATER

All six patients developed aluminium bone disease and their median blood aluminium concentration was 17 µg/L (IQR 13-100).

CONCLUSIONS

Toxic aluminium exposure can result in neurotoxicity and bone disease, especially in patients with chronic kidney disease. Adults with stage 5 chronic kidney disease chronically exposed to aluminium developed aluminium neurotoxicity at higher concentrations than those with aluminium bone disease or with asymptomatic aluminium overload. Aluminium neurotoxicity was reported at lower concentrations following acute exposure to intravesical aluminium. Extrapolating the relevance of these concentrations to the general population is problematic in that the data were derived from oncology patients, however, the possibility that aluminium neurotoxicity may occur at concentrations lower that those reported historically in patients with stage 5 chronic kidney disease cannot be excluded.

Shift from darbepoetin-α to continuous erythropoietin receptor activator decreases serum aluminium concentration in patients on hemodialysis

OBJECTIVE

The response of erythropoietic stimulating agents (ESA) in uremic patients may be associated with the changes of biochemical parameters, metal elements and inflammation status during the shift from one ESA to another.

METHOD

We compared changes in above mentioned factors after switching from darbepoetin-α (DPO) 20μg weekly for 10 weeks to continuous erythropoietin receptor activator (CERA) 100μg monthly for 10 weeks in uremic patients on hemodialysis. The haematocrit (Hct), metal elements and inflammation status are the primary outcome. Subjects included 54 patients without transfusion or bleeding or additional ESAs. Responders (IR, n=36) were defined as patients with an increase in Hct after the swtich.

RESULT

Although there was no significant difference in overall mean Hct after the switch (p=0.135), there are significantly greater mean number of red blood cells (RBC) (p=0.006), higher platelet numbers (p=0.001), larger RBCs (p=0.017) and higher creatinine (p=0.04) and total cholesterol (T-CHOL) (p=0.003) levels. Mean overall aluminium (Al) level decreased significantly (p=0.001). C-reactive protein (CRP) also decreased (p=0.016). The overall LDH increased (p=0.049) and potassium decreased significantly (p=0.036), which indicating active erythropoiesis. The calcium (Ca) level was significantly higher (p=0.034) and phosphate was significantly lower (p=0.028) after the shift. Although there was no significant increase in overall levels of parathyroid hormone (PTH) after the shift (p=0.061), but the pre-shift and post-shift PTH level was significantly higher in IRs than in non-IRs (p=0.003 and p=0.027, respectively). IRs had a significantly lower initial T-CHOL (p=0.03) and initial CRP (p=0.012) than non-responders, which may be related to lower inflammation.

CONCLUSION

We found the shift from DPO to CERA results in lower Al levels, a reduced inflammatory response, and an increase in RBC number and PTH level in uremic patients on hemodialysis.

Aluminium and lead abnormalities in children on haemodialysis: relationship with some medications

INTRODUCTION

The determination of toxic elements in the biological samples of human beings is an important clinical procedure. This study was performed to investigate the prevalence of abnormal blood contents of 2 trace elements (TEs), aluminum (Al),and lead (Pb) in hemodialysis (HD) patients and to analyze their relationship with the medications, such as CaCO(3), Ca acetate, 1,25-dihydroxy vit. D(3), and erythropoietin (EPO), as well as hematocrit level.

MATERIAL AND METHODS

We included 43 patients on maintenance HD and they had continued the previously mentioned medications for at least 3 months. None of the patients were on Al containing phosphate binding agents.

RESULTS

Serum aluminum and lead levels were significantly increased than in the healthy controls, but levels of both of them were far below toxic values. Male patients had higher mean levels of lead than did females. A strong positive correlation was found between serum Al and serum Pb levels among patients (r = 0.075, p = 0.0001).The serum level of Pb was positively correlated with the serum albumin in HD patients (r = 0.45, p = 0.03). Both serum aluminium and lead levels positively correlated with the EPO dose taken by the patients (r = 0.77, p = 0.0001 and r = 0.67, p = 0.0001 respectively).

CONCLUSIONS

The blood level of trace metals of these HD patients was not related to their medications except for the EPO dose. However, caution must be exercised in interpreting this result as dose and duration of medication may play an important role. Al and Pb over load may be considered from the causes of inadequate response to epoetin therapy.