Chronic Kidney Disease of Unknown Cause in Agricultural Communities

Climate change and its implications for kidney health

PURPOSE OF REVIEW

Extremes of weather as a result of climate change are affecting social, economic and health systems. Kidney health is being threatened by global warming while treatment of kidney disease is contributing to increasing resource utilization and leaving a substantial carbon footprint. Improved physician awareness and patient education are needed to mitigate the risk.

RECENT FINDINGS

Rising temperatures are changing kidney disease patterns, with increasing prevalence of acute kidney injury, chronic kidney disease and kidney stones. These issues disproportionately affect people suffering from social inequality and limited access to resources.

SUMMARY

In this article, we review the effects of climate change on kidney stones, and acute and chronic kidney injury. Finally, we discuss the impact of renal replacement therapies on the environment and proposed ways to mitigate it.

Effects on household income and earnings from chronic kidney disease of non-traditional origins: PREP project findings from Chichigalpa, Nicaragua

OBJECTIVE

Our purpose with this study is to examine the socioeconomic outcomes associated with chronic kidney disease not related to well-known risk factors (CKDnt) in four communities in Chichigalpa, Nicaragua that are home to a substantial number of sugarcane workers.

METHODS

We employed a cluster-based systematic sampling design to identify differences in outcomes between those households affected directly by CKDnt and those that are not.

RESULTS

Overall, we find that approximately one-third of households surveyed had a household member diagnosed with CKDnt. 86% of CKDnt households reported that the head of the household had been without work for the last 6 months or more, compared with 53% of non-CKDnt households. Non-CKDnt households took in more than double the earnings income on average than CKDnt households ($C52 835 and $C3120, respectively). Nonetheless, on average, CKDnt households' total income exceeded that of non-CKDnt households due to Nicaragua's national Instituto Nicaraguense de Seguridad Social Social Security payments to CKDnt households, suggestive of a substantial economic burden on the state resulting from the disease. Households headed by widows or widowers who are widowed as a result of CKDnt demonstrate distinct deficits in total income when compared with either non-widowed households or to households widowed by causes other than CKDnt.

CONCLUSIONS

Despite strong similarities in terms of demographic characteristics and despite residing in the same communities with similar access to the available resources, households experiencing CKDnt exhibit distinct and statistically significant differences in important socioeconomic outcomes when compared to non-CKDnt households.

What every clinician needs to know about chronic kidney disease: Detection, classification and epidemiology

Chronic kidney disease (CKD) is a major healthcare challenge, affecting >800 million people worldwide. Implications for population health result from the strong associations of CKD with increased rates of cardiovascular disease, heart failure, progressive CKD leading to kidney failure, acute kidney injury (AKI), and mortality. In addition to a single disease perspective, CKD commonly coexists alongside other long-term conditions, in particular type 2 diabetes and cardiovascular disease. CKD is therefore an important component of multimorbidity that influences individual management and impacts prognosis. CKD is defined by abnormalities of kidney structure or function of any cause with implications for health that are present for longer than 3 months. The diagnosis is usually made on the basis of an abnormal glomerular filtration rate (GFR < 60 mL/min/1.73 m2) and/or the presence of proteinuria (urine albumin to creatinine ratio > 30 mg/g or >3 mg/mmol). GFR is usually estimated from serum creatinine concentration using a variety of validated equations. However, serum creatinine is closely related to muscle mass and may therefore not be an accurate marker of GFR in people with high or low muscle mass (sarcopaenia). Cystatin C is an alternative endogenous marker of GFR that is increasingly being used but also has limitations. An estimate of GFR based on both creatinine and cystatin C is the most accurate. Diagnosis should be followed by classification and risk stratification to guide the development of a risk-based, personalized care plan. Improved detection and widespread implementation of optimal CKD management has the potential to bring major benefits to population health.

Organization and Structures for Detection and Monitoring of CKD Across World Countries and Regions: Observational Data From a Global Survey

RATIONALE & OBJECTIVE

Established therapeutic interventions effectively mitigate the risk and progression of chronic kidney disease (CKD). Countries and regions have a compelling need for organizational structures that enable early identification of people with CKD who can benefit from these proven interventions. We aimed to report the current global status of CKD detection programs.

STUDY DESIGN

A multinational cross-sectional survey.

SETTING & PARTICIPANTS

Stakeholders, including nephrologist leaders, policymakers, and patient advocates from 167 countries, participating in the International Society of Nephrology (ISN) survey from June to September 2022.

OUTCOMES

Structures for the detection and monitoring of CKD, including CKD surveillance systems in the form of registries, community-based detection programs, case-finding practices, and availability of measurement tools for risk identification.

ANALYTICAL APPROACH

Descriptive statistics.

RESULTS

Of all participating countries, 19% (n=31) reported CKD registries and 25% (n=40) reported implementing CKD detection programs as part of their national policies. There were variations in CKD detection program, with 50% (n=20) using a reactive approach (managing cases as identified) and 50% (n=20) actively pursuing case-finding in at-risk populations. Routine case-finding for CKD in high-risk populations was widespread, particularly for diabetes (n=152; 91%) and hypertension (n=148; 89%). Access to diagnostic tools, estimated glomerular filtration rate (eGFR) and urine albumin-creatinine ratio (UACR), was limited, especially in low-income (LICs) and lower-middle-income (LMICs) countries, at primary (eGFR: LICs 22%, LMICs 39%, UACR: LICs 28%, LMICs 39%) and secondary/tertiary healthcare levels (eGFR: LICs 39%, LMICs 73%, UACR: LICs 44%, LMICs 70%), potentially hindering CKD detection.

LIMITATIONS

A lack of detailed data prevented an in-depth analysis.

CONCLUSION

This comprehensive survey highlights a global heterogeneity in the organization and structures (surveillance systems, detection programs and tools) for early identification of CKD. Ongoing efforts should be geared toward bridging such disparities to optimally prevent the onset and progression of CKD and its complications.

Diagnostic accuracy of thermal, hydration, and heart rate assessments in discriminating positive acute kidney injury risk following physical work in the heat

Occupational heat stress increases the risk of acute kidney injury (AKI). This study presents a secondary analysis to generate novel hypotheses for future studies by investigating the diagnostic accuracy of thermal, hydration, and heart rate assessments in discriminating positive AKI risk following physical work in the heat in unacclimatized individuals. Unacclimatized participants (n = 13, 3 women, age: ∼23 years) completed four trials involving 2 h of exercise in a 39.7 ± 0.6 °C, 32 ± 3% relative humidity environment that differed by experimental manipulation of hyperthermia (i.e., cooling intervention) and dehydration (i.e., water drinking). Diagnostic accuracy was assessed via receiver operating characteristic curve analysis. Positive AKI risk was identified when the product of concentrations insulin-like growth factor binding protein 7 and tissue inhibitor of metalloproteinase-2 [IGFBP7∙TIMP-2] exceeded 0.3 (ng∙mL-1)2∙1000-1. Peak absolute core temperature had the acceptable discriminatory ability (AUC = 0.71, p = 0.009), but a relatively large variance (AUC 95% CI: 0.57-0.86). Mean body temperature, urine specific gravity, urine osmolality, peak heart rate, and the peak percent of both maximum heart rate and heart rate reserve had poor discrimination (AUC = 0.66-0.69, p ≤ 0.051). Mean skin temperature, percent change in body mass and plasma volume, and serum sodium and osmolality had no discrimination (p ≥ 0.072). A peak increase in mean skin temperature of >4.7 °C had a positive likelihood ratio of 11.0 which suggests clinical significance. These data suggest that the absolute value of peak core temperature and the increase in mean skin temperature may be valuable to pursue in future studies as a biomarker for AKI risk in unacclimatized workers.

Prediction models for earlier stages of chronic kidney disease

PURPOSE OF REVIEW

Identifying patients with risk of developing progressive chronic kidney disease (CKD) early is an important step in improving kidney care. This review discusses four recently developed models, two which predict risk of new onset disease, and two which predict progression earlier in the course of disease.

RECENT FINDINGS

Several models predicting CKD incidence and progression have been recently developed and externally validated. A connecting theme across these models is the use of data beyond estimated glomerular filtration rate, allowing for greater accuracy and personalization. Two models were developed with stratification by diabetes status, displaying excellent model fit with and without variables like use of diabetes medication and hemoglobin A1C. Another model was designed to be patient facing, not requiring the knowledge of any laboratory values for use. The final model was developed using lab data and machine learning. These models demonstrated high levels of discrimination and calibration in external validation, suggesting suitability for clinical use.

SUMMARY

Models that predict risk of CKD onset and progression have the potential to significantly reduce disease burden, financial cost, and environmental output from CKD through upstream disease prevention and slowed progression. These models should be implemented and evaluated prospectively in primary care settings.

Extreme Heat and Occupational Health Risks

Climate change poses a significant occupational health hazard. Rising temperatures and more frequent heat waves are expected to cause increasing heat-related morbidity and mortality for workers across the globe. Agricultural, construction, military, firefighting, mining, and manufacturing workers are at particularly high risk for heat-related illness (HRI). Various factors, including ambient temperatures, personal protective equipment, work arrangements, physical exertion, and work with heavy equipment may put workers at higher risk for HRI. While extreme heat will impact workers across the world, workers in low- and middle-income countries will be disproportionately affected. Tracking occupational HRI will be critical to informing prevention and mitigation strategies. Renewed investment in these strategies, including workplace heat prevention programs and regulatory standards for indoor and outdoor workers, will be needed. Additional research is needed to evaluate the effectiveness of interventions in order to successfully reduce the risk of HRI in the workplace.

Exposome and Metabolome Analysis of Sugarcane Workers Reveals Predictors of Kidney Injury

Introduction

Sugarcane workers are exposed to potentially hazardous agrochemicals, including pesticides, heavy metals, and silica. Such occupational exposures present health risks and have been implicated in a high rate of kidney disease seen in these workers.

Methods

To investigate potential biomarkers and mechanisms that could explain chronic kidney disease (CKD) among this worker population, paired urine samples were collected from sugarcane cutters at the beginning and end of a harvest season in Guatemala. Workers were then separated into 2 groups, namely those with or without kidney function decline (KFD) across the harvest season. Urine samples from these 2 groups underwent elemental analysis and untargeted metabolomics.

Results

Urine profiles demonstrated increases in silicon, certain pesticides, and phosphorus levels in all workers, whereas heavy metals remained low. The KFD group had a reduction in estimated glomerular filtration rate (eGFR) across the harvest season; however, kidney injury marker 1 did not significantly change. Cross-harvest metabolomic analysis found trends of fatty acid accumulation, perturbed amino acid metabolism, presence of pesticides, and other known signs of impaired kidney function.

Conclusion

Silica and certain pesticides were significantly elevated in the urine of sugarcane workers with or without KFD. Future work should determine whether long-term occupational exposure to silica and pesticides across multiple seasons contributes to CKD in these workers. Overall, these results confirmed that multiple exposures are occurring in sugarcane workers and may provide insight into early warning signs of kidney injury and may help explain the increased incidence of CKD among agricultural workers.

Chronic kidney disease and the global public health agenda: an international consensus

Early detection is a key strategy to prevent kidney disease, its progression and related complications, but numerous studies show that awareness of kidney disease at the population level is low. Therefore, increasing knowledge and implementing sustainable solutions for early detection of kidney disease are public health priorities. Economic and epidemiological data underscore why kidney disease should be placed on the global public health agenda - kidney disease prevalence is increasing globally and it is now the seventh leading risk factor for mortality worldwide. Moreover, demographic trends, the obesity epidemic and the sequelae of climate change are all likely to increase kidney disease prevalence further, with serious implications for survival, quality of life and health care spending worldwide. Importantly, the burden of kidney disease is highest among historically disadvantaged populations that often have limited access to optimal kidney disease therapies, which greatly contributes to current socioeconomic disparities in health outcomes. This joint statement from the International Society of Nephrology, European Renal Association and American Society of Nephrology, supported by three other regional nephrology societies, advocates for the inclusion of kidney disease in the current WHO statement on major non-communicable disease drivers of premature mortality.

Chronic Interstitial Nephritis in Agricultural Communities: Observational and Mechanistic Evidence Supporting the Role of Nephrotoxic Agrochemicals

Chronic interstitial nephritis in agricultural communities (CINAC) is an epidemic of kidney disease affecting specific tropical and subtropical regions worldwide and is characterized by progressive CKD in the absence of traditional risk factors, such as hypertension and diabetes. CINAC prevalence is higher among young, male agricultural workers, but it also affects women, children, and nonagricultural workers in affected areas. Biopsies from patients with CINAC across regions commonly demonstrate tubular injury with lysosomal aggregates, tubulointerstitial inflammation, and fibrosis and variable glomerular changes. Each endemic area holds environmental risk factors and patient/genetic milieus, resulting in uncertainty about the cause(s) of the disease. Currently, there is no specific treatment available for CINAC. We highlight survey findings of Houston-based migrant workers with CINAC and draw similarities between kidney injury phenotype of patients with CINAC and mice treated chronically with paraquat, an herbicide used worldwide. We propose potential pathways and mechanisms for kidney injury in patients with CINAC, which may offer clues for potential therapies.

Heat exposure and chronic kidney disease: a temporal link in a Taiwanese agricultural county

Heat stress-related kidney injury has drawn public health attention. This study explored the temporal relationships between impaired kidney function and preceding outdoor heat exposure Taiwan. Data of participants collected through a health screening program was used to assess the association between chronic kidney disease (CKD) and average ambient temperature with various time lag structures. A total of 1,243 CKD cases and 38,831 non-CKD participants were included in the study. After adjusting for demographic, socioeconomic, lifestyle factors, and comorbidities, CKD was positively associated with the ambient temperature within 1-9 months. The 9-month average ambient temperature yielded the highest odds ratio of CKD (OR = 1.22; 95% CI = 1.09-1.37). Furthermore, females and farmers were found to be more vulnerable to CKD risk after outdoor heat exposure. These findings suggest that the prevention of heat stress-related kidney injury should consider relevant time frames and focus on vulnerable populations.

Health burden of sugarcane burning on agricultural workers and nearby communities

Sugarcane is the most widely cultivated crop in the world, with equatorial developing nations performing most of this agriculture. Burning sugarcane is a common practice to facilitate harvest, producing extremely high volumes of respirable particulate matter in the process. These emissions are known to have deleterious effects on agricultural workers and nearby communities, but the extent of this exposure and potential toxicity remain poorly characterized. As the epidemicof chronic kidney disease of an unknown etiology (CKDu) and its associated mortality continue to increase along with respiratory distress, there is an urgent need to investigate the causes, determine viable interventions to mitigate disease andimprove outcomes for groups experiencing disproportionate impact. The goal of this review is to establish the state of available literature, summarize what is known in terms of human health risk, and provide recommendations for what areas should be prioritized in research.

A longitudinal assessment of heat exposure and biomarkers of kidney function on heat shock protein 70 and antibodies among agricultural workers

Background

Exposure to extreme heat impacts millions of people worldwide and outdoor workers are among the populations most affected by high temperatures. Heat stress induces several biological responses in humans, including the production of heat shock proteins (HSP) and antibodies against HSP (anti-HSP) which may play a central role in the body's cellular response to a hot environment.

Objective

This longitudinal study investigated the impact of high temperatures and humidity on the presence of HSP70 and anti-HSP70 and examined relationships with markers of kidney function in an at-risk workforce under conditions of extreme heat and exertion in Guatemala.

Methods

We collected ambient temperature and relative humidity data as well as biomarkers and clinical data from 40 sugarcane workers at the start and the end of a 6-month harvest. We used generalized mixed-effects models to estimate temperature effects on HSP70 and anti-HSP70 levels. In addition, we examined trends between HSP70 and anti-HSP70 levels and markers of kidney function across the harvest.

Results

At the end of the harvest, temperatures were higher, and workers had, on average, higher levels of HSP70 and anti-HSP70 compared to the beginning of the season. We observed significant increasing trends with temperature indices and HSP70 levels. Maximum temperature was associated with HSP70 increments after controlling for age, systolic and diastolic blood pressure (β: 0.21, 95% Confidence Interval: 0.09, 0.33). Kidney function decline across the harvest was associated with both higher levels of anti-HSP70 levels at the end of the harvest as well as greater increases in anti-HSP70 levels across the harvest.

Conclusions

These results suggest that workplace heat exposure may increase the production of HSP70 and anti-HSP70 levels and that there may be a relationship between increasing anti-HSP70 antibodies and the development of renal injury. HSP70 holds promise as a biomarker of heat stress in exposed populations.

Kidney disease hotspots and water balance in a warming world

PURPOSE OF REVIEW

Geographically localized areas with a high prevalence of kidney disease exist currently in several regions of the world. Although the exact cause is unclear, environmental exposures accelerated by climate change, particularly heat exposure and ground water contamination, are hypothesized as putative risk factors. Aiming to inform investigations of water-related exposures as risk factors for kidney disease, we excavate the history of major water sources in three regions that are described as hotspots of kidney disease: the low-lying coastal regions in El Salvador and Nicaragua, the dry central region in Sri Lanka, and the Central Valley of California.

RECENT FINDINGS

Historic data indicate that these regions have experienced water scarcity to which several human-engineered solutions were applied; these solutions could be hypothesized to increase residents' exposure to putative kidney toxins including arsenic, fluoride, pesticides, and cyanobacteria. Combined with heat stress experienced in context of climate change, there is potential for multistressor effects on kidney function. Climate change will also amplify water scarcity, and even if regional water sources are not a direct risk factor for development of kidney disease, their scarcity will complicate the treatment of the relatively larger numbers of persons with kidney disease living in these hotspots.

SUMMARY

Nephrologists and kidney disease researchers need to engage in systematic considerations of environmental exposures as potential risk factors for kidney disease, including water sources, their increasing scarcity, and threats to their quality due to changing climate.

Social deprivation and kidney failure due to an undiagnosed nephropathy

BACKGROUND

In France, kidney diseases of undetermined origin account for 5%-20% of all causes of end-stage kidney disease. We investigated the impact of social disadvantage on the lack of aetiological diagnosis of nephropathies.

METHODS

Data from patients who started dialysis in France between 1 January 2017 and 30 June 2018 were extracted from the French Renal Epidemiology and Information Network registry. The social deprivation of each individual was estimated by the European Deprivation Index (EDI) defined by the patient's address. Logistic regression was used to perform mediation analysis to study the potential association between social deprivation and unknown nephropathy.

RESULTS

Of the 7218 patients included, 1263 (17.5%) had unknown kidney disease. A total of 394 (31.4%) patients in the unknown kidney disease belonged to the most deprived quintile of the EDI [fifth quintile (Q5)], vs 1636 (27.5%) patients in the known kidney disease group. In the multivariate analysis, unknown kidney disease was associated with Q5 (odds ratio 1.40, 95% confidence interval 1.12-1.74, P = .003). Mediation analysis did not identify any variables (e.g. obesity, initiation of dialysis in emergency, number of visits to the general practitioner and nephrologist before initiation of dialysis, date of first nephrology consultation) that mediated the association between social deprivation and nephropathy of unknown origin.

CONCLUSIONS

Our results show that, compared with nondeprived subjects, individuals experiencing social deprivation have a higher risk of unknown nephropathy at dialysis initiation. However, mediation analysis did not identify any variables that explained the association between social deprivation and nephropathy of unknown origin.

Increased ambient outdoor temperatures are associated with increased disease flaring in hidradenitis suppurativa

Despite evidence to suggest a relationship between time of year and hidradenitis suppurativa (HS) flaring, no studies have been conducted to date to establish a relationship directly between temperature and flaring. In this study, we aim to validate a classification approach based on administrative data for identifying medical encounters that likely represent HS flares in patient with a known diagnosis of HS within the Mass General Brigham Health System (MGB) and examine the relationship between average daily temperatures and HS disease flaring among patients in Boston. This is a retrospective cohort study. Participants were individuals with HS presenting to emergency departments or dermatology outpatient clinics with disease flares between January 2017 and January 2022. The average number of encounters for HS flares was compared with the temperature for that day and the 3- and 7-day periods prior. There were 2567 patient encounters for HS flares included in the study. Of the total identified HS flares, 75.6% occurred in females and 39.1% occurred in patients who identified as Black. Uniformly small but statistically significant relationships were noted between increased temperature and presentations for hidradenitis suppurativa flare with the highest correlation coefficient (0.0768) noted with a 3-day lag time between the heat experienced and day of presentation for flare. Increased temperature is associated with a small, but statistically significant increase in HS disease flaring. As such, HS disease flaring may rise as global temperatures do, suggesting an increase in the global burden of HS as climate change persists.

Advances in the management of chronic kidney disease

Chronic kidney disease (CKD) represents a global public health crisis, but awareness by patients and providers is poor. Defined as persistent abnormalities in kidney structure or function for more than three months, manifested as either low glomerular filtration rate or presence of a marker of kidney damage such as albuminuria, CKD can be identified through readily available blood and urine tests. Early recognition of CKD is crucial for harnessing major advances in staging, prognosis, and treatment. This review discusses the evidence behind the general principles of CKD management, such as blood pressure and glucose control, renin-angiotensin-aldosterone system blockade, statin therapy, and dietary management. It additionally describes individualized approaches to treatment based on risk of kidney failure and cause of CKD. Finally, it reviews novel classes of kidney protective agents including sodium-glucose cotransporter-2 inhibitors, glucagon-like peptide-1 receptor agonists, non-steroidal selective mineralocorticoid receptor antagonists, and endothelin receptor antagonists. Appropriate, widespread implementation of these highly effective therapies should improve the lives of people with CKD and decrease the worldwide incidence of kidney failure.

Occupational Silica Exposure as a Potential Risk for Microscopic Polyangiitis

Microscopic polyangiitis is an important and common component of cytoplasmic antibody-associated vasculitides that can lead to serious morbidity and even death. A clear causative etiology has not been identified. Although silica is well known to produce lung damage, the negative renal effects of silica exposure should not be overlooked. We present a case of renal dysfunction associated with silica exposure, its diagnosis by renal biopsy, and the treatment method used. Environmental or occupational silica exposure can cause microscopic polyangiitis. Working in occupations with increased risk of silica exposure may result in serious medical problems.

Chronic Kidney Disease Among Agricultural Workers in Taiwan: A Nationwide Population-Based Study

Introduction

Chronic kidney disease (CKD) in agricultural communities is a significant public health issue. We aimed to investigate the epidemiology of CKD among Taiwanese farmers and its association with outdoor heat exposure.

Methods

A nested case-control study was conducted on participants in the National Adult Health Examination (NAHE) from 2012 to 2018. The farming occupation was identified through National Health Insurance data. The primary outcomes of interest were the development of CKD, defined as a decreased estimated glomerular filtration rate (eGFR) with diagnosis by physicians, and CKD of undetermined etiology (CKDu), defined as CKD excluding common traditional etiologies. We calculated the county-wide average ambient temperature from a climate reanalysis dataset (ERA5-Land). All CKD cases were matched 1:2 to non-CKD participants by age and biological sex. We estimated the odds ratios (ORs) of CKD and CKDu for farmers and changes in mean ambient temperature (°C) before the examination.

Results

We identified 844,412 farmers and 3,750,273 nonfarmers. Among 24.9% of farmers and 7.4% of nonfarmers with reduced kidney function, only 1 in 7 received a diagnosis of CKD. The farming occupation was independently predictive of CKDu (OR = 1.09, 95% confidence interval [CI] = 1.001-1.18) but not CKD. Increased ambient temperature (°C) was associated with a higher risk of CKD (OR = 1.023, 95% CI = 1.017-1.029), with particularly strong associations observed among middle-aged participants and diabetics.

Conclusions

Taiwanese farmers might have a higher risk of developing CKDu. Outdoor heat exposure is associated with the development of CKD, and middle-aged participants and those with diabetes are more vulnerable than the general population.

Risky working conditions and chronic kidney disease

BACKGROUND

Individuals in the workplace are exposed to various environments, tasks, and schedules. Previous studies have indicated a link between occupational exposures and an increased risk of chronic kidney disease (CKD). However, the social conditions of the work environment may also be a crucial contributing factor to CKD. Furthermore, individuals may encounter multiple occupational-related risk factors simultaneously, underscoring the importance of investigating the joint risk of different working conditions on CKD.

METHODS

A prospective analysis of 65,069 UK Biobank participants aged 40 to 69 years without CKD at baseline (2006-2010) was performed. A self-administered questionnaire assessed working conditions and a working conditions risk score were developed. Participants who answered "sometimes" or "often" exposure to occupational heat or occupational secondhand cigarette smoke; involved in shift work or heavy workloads ("usually" or "always"), were grouped as high-risk working conditions. Each working condition was scored as 1 if grouped as high-risk, and 0 if not. The working conditions risk score was equal to the sum of these four working conditions. Cox proportional hazard regression models were used to estimate the associations between working conditions and CKD incidence.

RESULTS

The mean follow-up time was 6.7 years. After adjusting for demographic, lifestyle, and working time factors, the hazard ratios for the development of CKD for heavy workloads, shift work, occupational secondhand cigarette smoke exposure, and occupational heat exposure were 1.24 (95%CI = 1.03, 1.51), 1.33 (95%CI = 1.10, 1.62), 1.13 (95%CI = 1.01, 1.26), 1.11 (95%CI = 0.99, 1.24), respectively. The risk of CKD was found to be significantly associated with an increasing working conditions risk score. Individuals with a working conditions risk score of 4 had an 88.0% (95% CI = 1.05, 3.35) higher risk of developing CKD when compared to those with a working conditions risk score of 0.

CONCLUSIONS

Adverse working conditions, particularly when considered in combination, can significantly elevate the risk of chronic kidney disease (CKD). These results provide a reference for implementing measures to prevent CKD.

Kidney disease characteristics, prevalence, and risk factors in León, Nicaragua: a population-based study

BACKGROUND

CKD of unknown etiology (CKDu) disproportionately affects young people in Central America who lack traditional CKD risk factors (diabetes and hypertension) and has instead been variably linked to heat stress, occupational and environmental exposures, nephrotoxic medications, and/or genetic susceptibility. This study aimed to estimate the prevalence of CKD and identify risk factors for traditional CKD and CKDu in Nicaragua.

METHODS

Surveys and assessment for CKD markers in urine and serum were performed in 15-59 year olds in households of the León municipality of Nicaragua. The survey included questions on demographics, health behaviors, occupation, and medical history. Participants with CKD were subdivided into traditional CKD and suspected CKDu based on history of diabetes, hypertension, or other specified conditions. A multinomial logistic regression model was used to identify factors associated with traditional CKD and suspected CKDu, compared to the non-CKD reference group.

RESULTS

In 1795 study participants, CKD prevalence was 8.6%. Prevalence in males was twofold higher than females (12% vs 6%). Of those with CKD, 35% had suspected CKDu. Both traditional CKD and CKDu were associated with male sex and increasing age. Traditional CKD was associated with a family history of CKD, history of urinary tract infections, and lower socioeconomic status, while CKDu was associated with drinking well water and a lower body mass index.

CONCLUSIONS

Both traditional CKD and CKDu are significant burdens in this region. Our study supports previous hypotheses of CKDu etiology and emphasizes the importance of CKD screening.

Disease burden of chronic kidney disease attributable to lead exposure: A global analysis of 30 years since 1990

BACKGROUND

Exposure to lead (Pb) is associated with an increased risk of chronic kidney disease (CKD). However, limited studies explored the global burden of CKD attributable to Pb exposure, especially in countries with different development levels. This study aimed to comprehensively evaluate the temporal and spatial trend in the disease burden of CKD attributable to Pb exposure in 204 countries and territories from 1990 to 2019.

METHODS

We used the data from Global Burden of Disease Study (GBD) 2019 to estimate annual deaths, disability-adjusted life years (DALYs), age-standardized mortality rates (ASMR), and age-standardized DALYs rate (ASDR) of CKD attributable to Pb exposure. The annual average percentage change (AAPCs) was calculated using the Joinpoint model to evaluate the changing trend of CKD ASMR and ASDR attributable to Pb exposure from 1990 to 2019. Meanwhile, age-period-cohort (APC) model was used to assess changes in the mortality of CKD attributable to Pb exposure from 1990 to 2019.

RESULTS

Global ASMR for CKD attributable to Pb exposure trended upward from 1990 to 2019. ASMR and ASDR were the highest in low and low-middle SDI regions. With the APC model, we found that global mortality rates for CKD attributable to Pb exposure increased with age. The global period rate ratio showed the highest value in 2000-2004 and the lowest in 2015-2019, while the global cohort rate ratio showed the highest value in 1941-1949 and the lowest during 1986-1994.

CONCLUSIONS

From 1990 to 2019, the global burden of CKD attributable to Pb exposure increased globally, especially in low and low-middle SDI regions, as well as the elderly. Pb exposure is still a great threat to the global burden of CKD, and the implementation of effective prevention measures to reduce Pb exposure in the environment should be continually strengthened.

Clinical findings and kidney morphology in chronic kidney disease of unknown cause in India

BACKGROUND

Chronic kidney disease of unknown cause (CKDu) is an emerging health problem in India and other countries worldwide. However, clinical descriptions, including kidney pathology, are scarce.

METHODS

This is a descriptive case series of patients with CKDu from an endemic region in India, with a focus on clinical and biochemical characteristics, kidney biopsy findings, and environmental exposure. Patients with suspected CKDu, aged 20-65, and eGFR 30-80 mL/min/1.73 m2 from rural areas with endemic prevalence of CKDu were included. The exclusion criteria were diabetes mellitus, uncontrolled hypertension, proteinuria >1 g/24 h, or other known kidney diseases. The participants underwent kidney biopsies, and blood and urine samples were collected.

RESULTS

Fourteen participants (3 females, 11 males) with a mean eGFR of 53 (range 29-78) mL/min/1.73 m2 were included. Kidney biopsies showed a combination of chronic tubulointerstitial damage, glomerulosclerosis, and glomerular hypertrophy, with varying degrees of interstitial inflammation. Eight participants had polyuria (diuresis ≥ 3 L/day). The urinary sediments were bland, with no haematuria. Serum potassium and sodium levels were, in most cases, normal but within the lower reference interval.

CONCLUSION

The kidney morphology and clinical characteristics in patients with CKDu in India were similar to those described for CKDu in Central America and Sri Lanka.

Environmental Change, Changing Biodiversity, and Infections-Lessons for Kidney Health Community

There is a direct and accelerating connection between ongoing environmental change, the unprecedented decline in biodiversity, and the increase in infectious disease epidemiology worldwide. Rising global temperatures are threatening the biodiversity that underpins the richness and diversity of flora and fauna species in our ecosystem. Anthropogenic activities such as burning fossil fuels, deforestation, rapid urbanization, and expanding population are the primary drivers of environmental change resulting in biodiversity collapse. Climate change is influencing the emergence, prevalence, and transmission of infectious diseases both directly and through its impact on biodiversity. The environment is gradually becoming more suitable for infectious diseases by affecting a variety of pathogens, hosts, and vectors and by favoring transmission rates in many parts of the world that were until recently free of these infections. The acute effects of these zoonotic, vector and waterborne diseases are well known; however, evidence is emerging about their role in the development of chronic kidney disease. The pathways linking environmental change and biodiversity loss to infections impacting kidney health are diverse and complex. Climate change and biodiversity loss disproportionately affect the vulnerable and limit their ability to access healthcare. The kidney health community needs to contribute to the issue of environmental change and biodiversity loss through multisectoral action alongside government, policymakers, advocates, businesses, and the general population. We describe various aspects of the environmental change effects on the transmission and emergence of infectious diseases particularly focusing on its potential impact on kidney health. We also discuss the adaptive and mitigation measures and the gaps in research and policy action.

Epigallocatechin-3-gallate in combination with corticosteroids mitigates heat stress-induced acute kidney injury through modulating heat shock protein 70 and toll-like receptor 4-dependent pathways

Recently, recurrent heat stress (HS) and dehydration have been exhibited to give rise to kidney disease epidemic in hot regions. The current study was carried out to estimate a possible renoprotective effect of dexamethasone (Dexa) and epigallocatechin-3-gallate (EGCG) as a heat shock protein (HSP)-70 inhibitor on HS-induced nephropathy. In total, five groups of rats were used: control group, HS group (exposed to heat for 40 min), Dexa+HS group (rats were injected with Dexa i.p.15 mg/kg/day for 3 days followed by HS), EGCG+HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days followed by HS), and EGCG+ Dexa +HS group (rats received EGCG 100 mg/kg/day, orally, for 7 days and injected Dexa as described along the last 3 days followed by HS). Kidney sections were stained with H&E and scored for tubular injury. A marked increase in creatinine, urea, malondialdehyde (MDA), monocyte chemoattractant protein (MCP)-1, HSP-70, nuclear factor kappa B (NF-κB), toll-like receptor 4 (TLR-4) and Caspase-3 expression was observed after HS induction (p < 0.001). Treatment with EGCG combined with Dexa notably reduced tubular injury, MCP-1, HSP-70, NF-κB, and TLR-4 levels (p < 0.001). Moreover, it increased IL-10, antioxidant capacity and Bcl-2 expression levels in the kidney (p < 0.001). This renoprotective impact might be attributed to anti-inflammatory, antioxidant, and anti-apoptotic mechanisms besides interfering with TLR-4-mediated NF-κB activation pathway.

Occupational Heat Stress and Kidney Health in Salt Pan Workers

Introduction

Work in heat affects millions of workers. Although kidney function in agricultural workers is increasingly researched, nonagricultural studies are scarce. In coastal salt pans, the absence of occupational exposures to pesticides and other toxicants allows assessment of heat stress alone.

Methods

Seven Indian salt pans were surveyed from 2017 to 2020. Job-specific workload was assessed. Heat stress was characterized as exceeding the wet bulb globe temperature (WBGT)-threshold limit value (TLV) for high and moderate workloads. Preshift and postshift heart rates (HRs), tympanic temperatures, and urine specific gravity (USG) were measured for 352 workers, as were sweat rates (SwR), serum creatinine (SCr), serum uric acid, and urine dipstick. Estimated glomerular filtration rate (eGFR; ml/min per 1.73 m²) was computed. Heat-strain symptoms were assessed using questionnaires.

Results

The mean WBGT was 30.5 ± 1.3 °C (summer) and 27.8 ± 1.9 °C (winter). Water intake during the workday was low, median was one Litre, and most workers (87%) exceeded the TLV for heat stress. Dehydration-related symptoms were frequent in those with high-heat stress, as were cross-shift increases in temperature (≥1°C; 15%), a high USG (≥1.020; 28%), and a high SwR (≥1 l/h; 53%). An eGFR of 60 to 89 ml/min per 1.73 m² was observed in 41% of all workers examined, and 7% had eGFR below 60 ml/min per 1.73 m². The odds ratio for eGFR <90 ml/min per 1.73 m² in workers exceeding the TLV, compared to workers below this limit, adjusted for age and gender was 2.9 (95% CI: 1.3-6.4).

Conclusion

Workplace interventions to prevent heat stress and dehydration in the salt pans and other at-risk industries are urgently required. The findings strengthen the notion that high-heat stress and limited hydration is a risk factor for kidney dysfunction.

How Does Environmental Temperature Affect Farmworkers' Work Rates in the California Heat Illness Prevention Study?

OBJECTIVE

Estimate the association between environmental temperature (wet bulb globe temperature [WBGT]) and work rate over the course of a workday.

METHODS

Repeated-measures regression was used to identify characteristics impacting work rate in a cross-sectional study of Latino farmworkers. Minute-by-minute work rate (measured by accelerometer) and WBGT were averaged over 15-minute intervals.

RESULTS

Work rate decreased by 4.34 (95% confidence interval [CI], -7.09 to -1.59) counts per minute per degree Celsius WBGT in the previous 15-minute interval. Cumulative quarter hours worked (2.13; 95% CI, 0.82 to 3.45), age (-3.64; 95% CI, -4.50 to -2.79), and dehydration at the end of workday (51.37; 95% CI, 19.24 to 83.50) were associated with counts per minute as were gender, pay type (piece rate vs hourly) and body mass index ≥25 kg/m 2 . The effects of pay type and body mass index were modified by gender.

CONCLUSION

Increased temperature was associated with a decrease in work rate.

Urinary Metabolomic Profile of Youth at Risk of Chronic Kidney Disease in Nicaragua

Key Points

Urinary concentrations of glycine, a molecule associated with thermoregulation, were elevated among youth from a high-risk region for chronic kidney disease of non-traditional etiology (CKDnt). Urinary concentrations of pyruvate, citric acid, and inosine were lower among youth at higher risk of CKDnt, suggesting renal stress. Metabolomic analyses may shed light on early disease processes or profiles or risk in the context of CKDnt.

Background

CKD of a nontraditional etiology (CKDnt) is responsible for high mortality in Central America, although its causes remain unclear. Evidence of kidney dysfunction has been observed among youth, suggesting that early kidney damage contributing to CKDnt may initiate in childhood.

Methods

Urine specimens of young Nicaraguan participants 12–23 years without CKDnt (n =136) were analyzed by proton nuclear magnetic resonance spectroscopy for 50 metabolites associated with kidney dysfunction. Urinary metabolite levels were compared by, regional CKDnt prevalence, sex, age, and family history of CKDnt using supervised statistical methods and pathway analysis in MetaboAnalyst. Magnitude of associations and changes over time were assessed through multivariable linear regression.

Results

In adjusted analyses, glycine concentrations were higher among youth from high-risk regions (β =0.82, [95% confidence interval, 0.16 to 1.85]; P = 0.01). Pyruvate concentrations were lower among youth with low eGFR (β = −0.36 [95% confidence interval, −0.57 to −0.04]; P = 0.03), and concentrations of other citric acid cycle metabolites differed by key risk factors. Over four years, participants with low eGFR experienced greater declines in 1-methylnicotinamide and 2-oxoglutarate and greater increases in citrate and guanidinoacetate concentrations.

Conclusion

Urinary concentration of glycine, a molecule associated with thermoregulation and kidney function preservation, was higher among youth in high-risk CKDnt regions, suggestive of greater heat exposure or renal stress. Lower pyruvate concentrations were associated with low eGFR, and citric acid cycle metabolites, such as pyruvate, likely relate to mitochondrial respiration rates in the kidneys. Participants with low eGFR experienced longitudinal declines in concentrations of 1-methylnicotinamide, an anti-inflammatory metabolite associated with anti-fibrosis in tubule cells. These findings merit further consideration in research on the origins of CKDnt.

Understanding Similarities and Differences in CKD and Dialysis Care in Children and Adults

In lower-income settings there is often a dearth of resources and nephrologists, especially pediatric nephrologists, and individual physicians often find themselves caring for patients with chronic kidney diseases and end-stage kidney failure across the age spectrum. The management of such patients in high-income settings is relatively protocolized and permits high-volume services to run efficiently. The basic principles of managing chronic kidney disease and providing dialysis are similar for adults and children, however, given the differences in body size, causes of kidney failure, nutrition, and growth between children and adults with kidney diseases, nephrologists must understand the relevance of these differences, and have an approach to providing quality and safe dialysis to each group. Prevention, early diagnosis, and early intervention with simple therapeutic and lifestyle interventions are achievable goals to manage symptoms, complications, and reduce progression, or avoid kidney failure in children and adults. These strategies currently are easier to implement in higher-resource settings with robust health systems. In many low-resource settings, kidney diseases are only first diagnosed at end stage, and resources to pay out of pocket for appropriate care are lacking. Many barriers therefore exist in these settings, where specialist nephrology personnel may be least accessible. To improve management of patients at all ages, we highlight differences and similarities, and provide practical guidance on the management of children and adults with chronic kidney disease and kidney failure. It is important that children are managed with a view to optimizing growth and well-being and maximizing future options (eg, maintaining vein health and optimizing cardiovascular risk), and that adults are managed with attention paid to quality of life and optimization of physical health.

Prevalence and predictors of chronic kidney disease of undetermined causes (CKDu) in Western Kenya's "sugar belt": a cross-sectional study

BACKGROUND

Epidemics of chronic kidney disease of undetermined causes (CKDu) among young male agricultural workers have been observed in many tropical regions. Western Kenya has similar climatic and occupational characteristics as many of those areas. The study objectives were to characterize prevalence and predictors of CKDu, such as, HIV, a known cause of CKD, in a sugarcane growing region of Kenya; and to estimate prevalence of CKDu across occupational categories and evaluate if physically demanding work or sugarcane work are associated with reduced eGFR.

METHODS

The Disadvantaged Populations eGFR Epidemiology Study (DEGREE) protocol was followed in a cross-sectional study conducted in Kisumu County, Western Kenya. Multivariate logistic regression was performed to identify predictors of reduced eGFR.

RESULTS

Among 782 adults the prevalence of eGFR < 90 was 9.85%. Among the 612 participants without diabetes, hypertension, and heavy proteinuria the prevalence of eGFR < 90 was 8.99% (95%CI 6.8%, 11.5%) and 0.33% (95%CI 0.04%, 1.2%) had eGFR < 60. Among the 508 participants without known risk factors for reduced eGFR (including HIV), the prevalence of eGFR < 90 was 5.12% (95%CI 3.4%, 7.4%); none had eGFR < 60. Significant risk factors for reduced eGFR were sublocation, age, body mass index, and HIV. No association was found between reduced eGFR and work in the sugarcane industry, as a cane cutter, or in physically demanding occupations.

CONCLUSION

CKDu is not a common public health problem in this population, and possibly this region. We recommend that future studies should consider HIV to be a known cause of reduced eGFR. Factors other than equatorial climate and work in agriculture may be important determinants of CKDu epidemics.

Interstitial Nephritis: Wherefrom, Wherein, and Whereto

Abnormalities of the renal interstitium were noted early while identifying chronic kidney disease in 1827; however, interest in glomerular and vascular lesions was then distracted from their further study. As a complication of scarlet fever, interstitial lesions attracted attention in 1859 and came to be defined as acute interstitial nephritis in 1898. The chronic form of interstitial nephritis was traditionally attributed to pyelonephritis until the advent of kidney biopsy in the 1950s, when interstitial lesions were recognized as an independent primary cause of chronic kidney disease from studies of analgesic nephropathy and vesico-ureteral reflux. The term tubulointerstitial nephritis was introduced in 1963 and promoted to denote the role of the tubules in the pathogenesis and the clinical presentation of interstitial nephritis as tubular dysfunction. Studies since then have established that fibrotic tubulointerstitial nephritis lesions correlate best with the severity and progression of kidney diseases independent of their etiology.

Urinary concentrations of metals before and after volcanic eruption: a natural experiment surrounding the eruption of Volcán de Fuego, 2018

Volcanic eruptions increase environmental heavy metal concentrations, yet little research has been performed on their extrapulmonary human health effects. We fortuitously collected biological samples in a cohort of Guatemalan sugarcane cutters in the area surrounding Volcán de Fuego before and after the June 2018 eruption. We sought to determine whether stratovolcanic activity was associated with changes in urinary concentrations of heavy metals in a cohort of sugarcane workers. In this exploratory analysis, we found significant increases in urinary arsenic, (β = 1.46, P < 0.0001), cadmium (β = 1.03, P < 0.0001), and lead (β = 0.87, P = 0.003) in participants with residential proximity to Volcán de Fuego as compared to participants farther away, suggesting that volcanic activity could be associated with acute heavy metal exposures. This natural experiment is, to our knowledge, the first of its kind and suggests a need for more research into heavy metal exposure-related health impacts of volcanic eruptions.

Environmental and Social Factors Associated with High Chronic Kidney Disease Mortality Rates in Municipalities of Guatemala: An Ecological Study of Municipal-Level Mortality Data

The purpose of this study was to determine the association between social and environmental indicators and high mortality rates from chronic kidney disease (CKD) in municipalities of Guatemala. An ecological study of municipal-level factors associated with CKD mortality in Guatemala was conducted. Crude mortality rates were calculated for the 2009-2019 period for each of the country's 340 municipalities, by gender and age groups. Municipal-level social and environmental indicators were used as independent variables. Linear regression was used for bivariate and multivariate analysis. A total of 28,723 deaths from CKD were documented for the 2009-2019 period. Average crude mortality rate for all ages for the country's 340 municipalities was 70.66 per 100,000 [0-502.99]. Very highly positive associations with high mortality rates were found in two agrarian territories where land use is mainly for permanent crops (e.g., sugar cane, coffee, rubber, banana, plantain, African palm) and pastures for cattle, with very low percentages of land covered by forests or protected areas. Social factors related to poverty and environmental factors related to agricultural use of land may play a role in the high CKD mortality rates documented in a cluster of municipalities of Guatemala.

Melatonin ameliorates glyphosate- and hard water-induced renal tubular epithelial cell senescence via PINK1-Parkin-dependent mitophagy

The combination of glyphosate (Gly) and hard water (Hwt) is a suspected risk factor for chronic interstitial nephritis in agricultural communities (CINAC). Accumulated mitochondrial damage and proximal tubular epithelial (PTE) cell senescence have been implicated in CINAC pathogenesis. Melatonin (Mel) has potential mitochondrial function and renoprotective properties, but its role and mechanism in CINAC are unknown. Here, we detected PTE cell senescence and PTEN-induced putative protein kinase 1 (PINK1)-parkin RBR E3 ubiquitin protein ligase (Parkin)-dependent mitophagy in mice orally administered with different doses of Gly combined with Hwt (Gly: 100 mg/kg·bw and 0.7 mg/L; Hwt: 2,500 mg/L CaCO₃ and 250 mg/L Ca²⁺) for different durations (12 and 36 w) using histological examination, transmission electron microscopy (TEM), immunofluorescence (IF) analysis, and immunohistochemistry (IHC), immunoblotting, ELISA and biochemical assays with kits. The same assays were performed after combination treatment with Mdivi-1 (an inhibitor of mitophagy, i.p. 10 mg/kg·bw, twice a week for 12 w) or Mel (i.p. 10 mg/kg·bw, once a day for 12 w) under high-level exposure. Gly combined with Hwt (Gly-Hwt) significantly increased P16-P21-dependent PTE cell senescence, mitochondrial fission and oxidative stress, and activated PINK1-Parkin-mediated mitophagy, accompanied by defective autophagic flux at high doses but unaltered autophagic flux at low doses. Improved senescence occurred after Mdivi-1 administration, suggesting that mitophagy is involved in cellular senescence. Mel significantly decreased senescence induced by Gly-Hwt. Furthermore, PINK1-Parkin-dependent mitophagy and autophagic flux were markedly enhanced, and mitochondrial function was improved, as evidenced by reductions in mitochondrial fission and subsequent oxidative damage. Thus, Gly and Hwt synergistically promote PTE cell senescence through PINK1-Parkin-mediated mitophagy, and Mel exerts renoprotective effects by modulating mitophagy, suggesting therapeutic applications in ageing-related CINAC.

Combined toxicity of acetamiprid and cadmium to larval zebrafish (Danio rerio) based on metabolomic analysis

Emerging contaminants, such as neonicotinoid pesticide acetamiprid (Ace), are frequently detected in the water environment, which can interact with existing heavy metal cadmium (Cd) to produce unpredicted influence. Limited studies have evaluated the effects of multiple pollutant exposures on aquatic animals. Here, we characterized the joint toxicity of Ace and Cd exposure to zebrafish (Danio rerio). The results revealed that Cd and its combined exposure with Ace had an inhibitory effect on the growth of larval zebrafish and induced morphological defects. Combined exposure to high doses of Ace and Cd could significantly reduce the levels of TG, glucose, and pyruvate in larval zebrafish. Untargeted metabolomics revealed that Cd treatment (285) produced more differentially expressed metabolites (DEMs) than Ace treatment (115), and combined treatment produced the most DEMs (294). The KEGG pathway enrichment analysis showed that they could disrupt riboflavin metabolism, amino acid metabolism, and glycolipid metabolism in the larvae of D. rerio. ELISA showed that VB2, FMN, and FAD levels were significantly increased. In addition, gene expression analysis exhibited that the mRNA levels of essential genes related to glycolipid metabolism were substantially affected, such as PK, PEPckc, PPAR-α, and FABP6. Furthermore, targeted amino acid metabolomics confirmed that both single exposure to Cd and combined exposure to Ace and Cd altered the levels of amino acids in larvae, including ALA, ARG, MET, PRO, TYR, VAL, GLY, ORN, and PHE. Taken together, exposure to Ace and Cd, alone or in combination, exerted harmful effects on the individual development, riboflavin metabolism, glycolipid metabolism, and amino acid metabolism disorder of D. rerio. These findings highlighted that more attention should be paid to the compound toxicity of chemical mixtures to aquatic organisms.

Acute Presentation of Mesoamerican Nephropathy in an Agricultural Worker From Panama

Mesoamerican nephropathy (MeN) is Central America's growing endemic renal disorder. No single cause is established, but many risk factors are hypothesized, such as young and medium-aged adults, male sex, work environment, heavy metals and agrochemicals exposure, occupational heat stress, nephrotoxic drug use, and low socioeconomic status. The diagnosis is confirmed by renal biopsy with chronic tubular atrophy and tubulointerstitial nephritis. If biopsies are unavailable, MeN is clinically suspected in patients residing in hotspot regions with a reduced estimated glomerular filtration rate (eGFR) and the absence of defining etiology, such as hypertension, diabetes, or glomerulonephritis. Currently, there is no specific treatment for which early diagnosis and intervention on risk factors is the primary strategy to improve prognosis. We report a case of a young male with agricultural labor exposure who presented with acute abdominal pain, back pain, and renal dysfunction that later progressed to chronic kidney disease (CKD) due to MeN. This case is significant because, although MeN is well-described in the literature, few cases of acute presentation have been documented.

"Failing kidneys in a failing planet; CKD of unknown origin"

The 'alarm clock' for human beings in the era of climate medicine has rung. Original diseases have appeared, that could not be explained and attributed to common causes, which are suggested to be linked to global warming and environmental factors. Such an indolent disease is the chronic kidney disease of unknown cause (CKDu), introduced also as Mesoamerican or Uddanam nephropathy. Scientists equate the climate impact on kidneys with the canary in the coal mine; coal miners used to carry caged canaries with them, so that if poisonous gases, such as methane or carbon monoxide leaked into the mine-shaft, the gases would kill the canary before killing the miners; similarly, kidneys are injured before devastating and lethal complications occur in humans. In some regions of Central America, the deaths due to chronic kidney disease increased by 177% with a death toll being as high as over 20,000. It was first documented in animals that periodic heat and dehydration have a major role in causing chronic kidney disease. Based on that observation, it is advocated that young male agricultural workers in Central America and South Asia, develop renal disease by getting exposed to extreme heat repeatedly. The clinico-pathological characteristics of this type of kidney injury, do not belong to an existing classification, even though a form of tubulo-interstitial renal disease has been proposed. In this review, we will discuss about CKDu, its epidemiology and pathophysiological mechanisms, clinical presentation and diagnostic biomarkers and examine potential therapeutic options.

Secular trends of epidemiologic patterns of chronic kidney disease over three decades: an updated analysis of the Global Burden of Disease Study 2019

OBJECTIVES

To assess the characteristics of the global death burden imposed by chronic kidney disease (CKD) and the attributable risk factors from 1990 to 2019 to help inform a framework for policy discussions, resource allocation and research priorities.

DESIGN

A population-based observational study.

SETTING

The death data and relative risk factors were obtained from the Global Burden of Disease (GBD) Study 2019 database.

MAIN OUTCOME MEASURES

Based on the GBD database, we estimated the death burden attributable to CKD stratified by sociodemographic index (SDI), geographic location, sex, age group, time period and risk factors from 1990 to 2019.

RESULTS

Over three decade study period, the global number of CKD-related deaths increased from 0.60 million (95% uncertainty interval (UI): 0.57-0.63 million) in 1990 to 1.43 million (95% UI: 1.31-1.52 million) in 2019. The age-standardised death rate (ASDR) of CKD, among all causes, increased from 15th in 1990 to 10th in 2019. Globally, the ASDR in males was higher than that in females. CKD-related deaths mainly occurred in those aged over 50 years, especially in regions with higher SDIs. The ASDR was negatively related to SDI (ρ=-0.603, p<0.0001). Among risk factors, metabolic risk factors, especially systolic blood pressure, fasting plasma glucose and body mass index, were the main contributors to CKD-related deaths. Although the high-temperature-related death burden was low, the trend increased sharply in lower SDI regions.

CONCLUSIONS

CKD-related deaths continue to increase, with the majority occurring in elderly adults. The CKD-related death burden is higher in males than in females. Additionally, the increasing high-temperature-related death burdens in lower SDI regions should receive social attention.

Climate and the Nephrologist: The Intersection of Climate Change, Kidney Disease, and Clinical Care

Climate change is upon us, and it will have a major effect on both kidney disease and the nephrology practice. But the converse is also true: our treatment of kidney disease has an effect on the climate. Much attention has focused on how rising temperatures can lead to acute and CKD and health exacerbations in patients with established kidney disease. Climate change is also associated with rising air pollution from wildfires and industrial wastes and infectious diseases associated with flooding and changing habitats, all of which heighten the risk of acute and CKD. Less well recognized or understood are the ways nephrology practices, in turn, contribute to still more climate change. Hemodialysis, although lifesaving, can be associated with marked water usage (up to 600 L per dialysis session), energy usage (with one 4-hour session averaging as much as one fifth of the total energy consumed by a household per day), and large clinical wastes (with hemodialysis accounting for one third of total clinical medicine-associated waste). Of note, >90% of dialysis occurs in highly affluent countries, whereas dialysis is much less available in the poorer countries where climate change is having the highest effect on kidney disease. We conclude that not only do nephrologists need to prepare for the rise in climate-associated kidney disease, they must also urgently develop more climate-friendly methods of managing patients with kidney disease.

Metabolic Features of Increased Gut Permeability, Inflammation, and Altered Energy Metabolism Distinguish Agricultural Workers at Risk for Mesoamerican Nephropathy

Mesoamerican nephropathy (MeN) is a form of chronic kidney disease found predominantly in young men in Mesoamerica. Strenuous agricultural labor is a consistent risk factor for MeN, but the pathophysiologic mechanism leading to disease is poorly understood. We compared the urine metabolome among men in Nicaragua engaged in sugarcane harvest and seed cutting (n = 117), a group at high risk for MeN, against three referents: Nicaraguans working less strenuous jobs at the same sugarcane plantations (n = 78); Nicaraguans performing non-agricultural work (n = 102); and agricultural workers in Spain (n = 78). Using proton nuclear magnetic resonance, we identified 136 metabolites among participants. Our non-hypothesis-based approach identified distinguishing urine metabolic features in the high-risk group, revealing increased levels of hippurate and other gut-derived metabolites and decreased metabolites related to central energy metabolism when compared to referent groups. Our complementary hypothesis-based approach, focused on nicotinamide adenine dinucleotide (NAD+) related metabolites, and revealed a higher kynurenate/tryptophan ratio in the high-risk group (p = 0.001), consistent with a heightened inflammatory state. Workers in high-risk occupations are distinguishable by urinary metabolic features that suggest increased gut permeability, inflammation, and altered energy metabolism. Further study is needed to explore the pathophysiologic implications of these findings.

An explorative study of inflammation-related proteins associated with kidney injury in male heat-stressed workers

Chronic kidney disease of non-traditional origin (CKDnt) and acute kidney injury (AKI) often affect heat-stressed Mesoamerican manual workers. Inflammation occurs concurrently with AKI in this population, but its role remains unknown. To explore links between inflammation and kidney injury in heat stress, we compared levels of inflammation-related proteins in cutters with and without increasing serum creatinine levels during sugarcane harvest. These sugarcane cutters have previously been identified to be repeatedly exposed to severe heat stress during the five month harvest season. A nested case-control study was conducted among male Nicaraguan sugarcane cutters in a CKDnt hotspot. Cases (n = 30) were defined as having an increase in creatinine of ≥0.3 mg/dL across the five-month harvest. Controls (n = 57) had stable creatinine levels. Ninety-two inflammation-related proteins in serum were measured before and after harvest using Proximity Extension Assays. Mixed linear regression was used to identify differences in protein concentrations between cases and controls before harvest, differential trends during harvest, and association between protein concentrations and the urine kidney injury markers Kidney Injury Molecule (KIM)-1, Monocyte Chemoattractant Protein (MCP)-1 and albumin. One protein, chemokine (C-C motif) ligand 23 (CCL23), was elevated among cases at pre-harvest. Changes in seven inflammation-related proteins (CCL19, CCL23, colony-stimulating factor 1 [CSF1], hepatocyte and fibroblast growth factors [HGF and FGF23], and tumor necrosis factor beta [TNFB] and TNF-related activation-induced cytokine [TRANCE]) were associated with case status and at least two out of three urine kidney injury markers (KIM-1, MCP-1 and albumin). Several of these have been implicated in myofibroblast activation, which likely is an important step in kidney interstitial fibrotic disease such as CKDnt. This study provides an initial exploration of immune system determinants of, and activation during, kidney injury experienced during prolonged heat stress.

Point-of-Care Testing in Chronic Kidney Disease of Non-Traditional Origin: Considerations for Clinical, Epidemiological, and Health Surveillance Research and Practice

Purpose

As the prevalence of chronic kidney disease of non-traditional origin (CKDnt) rises in low-resource settings, there is a need for reliable point-of-care creatinine testing. The purpose of this analysis was to assess the accuracy of two commonly used point-of-care creatinine devices, the i-STAT handheld (Abbott, Princeton, NJ, USA) and the StatSensor Creatinine (Nova Biomedical, Waltham, MA, USA) in comparison to venipuncture serum creatinine measures. The affordability, sensitivity, specificity, ease of use, and other considerations for each device are also presented.

Methods

Three paired data sets were compared. We collected 213 paired i-STAT and venipuncture samples from a community study in Nicaragua in 2015-2016. We also collected 267 paired StatSensor Creatinine and venipuncture samples, including 158 from a community setting in Nicaragua in 2014-2015 and 109 from a Guatemala sugarcane worker cohort in 2017-2018. Pearson correlation coefficients, Bland-Altman plots, and no intercept linear regression models were used to assess agreement between point-of-care devices and blood samples.

Results

The i-STAT performed the most accurately, overestimating creatinine by 0.07 mg/dL (95% CI: 0.02, 0.12) with no evidence of proportional bias. The StatSensor Creatinine performed well at low levels of creatinine (Mean (SD): 0.87 (0.19)). Due to proportional bias, the StatSensor Creatinine performed worse in the Nicaragua community setting where creatinine values ranged from 0.31 to 7.04 mg/dL.

Discussion

Both devices provide acceptable sensitivity and specificity. Although adequate for routine surveillance, StatSensor Creatinine is less accurate as the values of measured creatinine increase, a consideration when using the point-of-care device for screening individuals at risk for CKDnt. Research, clinical, and screening objectives, cost, ease of use, and background prevalence of disease must all be carefully considered when selecting a point-of-care creatinine device.

Conclusion

POC testing can be more accessible in resource-limited settings. The selection of the appropriate device will depend on the use-case.

Kidney Injury Biomarkers in Leptospirosis

Leptospirosis is a zoonotic infection with a global distribution, though it has a greater impact on marginalized rural agricultural and urban communities in developing countries. Kidney injury, which can lead to severe and lethal infections, is the most frequent complication associated with leptospirosis. Novel biomarkers are being studied as tools for assessing kidney injury in different pathological processes to improve early detection. This review aimed to gather information on the use of novel kidney biomarkers for human leptospirosis. A search of the literature was carried out in September 2021 using the parameters "((kidney) OR (renal) OR (chronic kidney disease) OR (acute kidney injury)) AND ((biomarker) OR (marker)) AND ((Leptospira) OR (leptospirosis))". The review identified 11 original studies that evaluated the performance of 15 kidney biomarkers related to leptospirosis. Assessment of the evidence for biomarker utility was limited because of the small number of studies and sample sizes. Although some biomarkers were associated with kidney disease, no specific biomarker appeared to be ready for clinical practice, and more research in this field is necessary.

Prevalence and Geographic Distribution of Self-Reported Chronic Kidney Disease and Potential Risk Factors in Central America

BACKGROUND

Cases for chronic kidney disease of unknown etiology (CKDu) are increasing in specific disease hotspots located in rural agricultural communities over Central America. The goal of the study was to estimate the prevalence and geographic distribution of self-reported work-related CKD and associated risk factors for CKDu by industry sector in Central America.

METHODS

We calculated the prevalence and distribution of self-reported CKD, work-related CKD, and suspected CKDu risk factors among the 9032 workers in the Second Central American Survey of Working Conditions and Health (II ECCTS, 2018). We mapped the distribution of suspected CKDu risk factors to work-related CKDu and weather conditions using average annual temperatures.

RESULTS

The primary and secondary industry sectors showed the highest proportion of males, suspected CKDu risk factors, and work-related CKD. Age (30-49 years: OR = 2.38, 95% CI 1.03-5.51), ethnicity (mestizo: OR, 7.44, 95% CI: 2.14-25.82), and exposure to high physical work demands (OR = 2.45, 95% CI: 1.18-5.09) were associated with work-related CKD. The majority of work-related CKD were reported in the western parts of Honduras and Nicaragua, in hot temperature regions, and overlapped with those areas with a high density of CKDu risk factors. Finally, some areas clustered CKDu risk factors without any work-related CKD points, mainly in the western part of Guatemala.

CONCLUSION

Our findings supplement prior CKDu findings regarding a high prevalence of work-related CKD among 30- to 49-year-old mestizo males in the primary and secondary sectors, in hot temperature areas, in the central and western region, and overlapping with persons reporting two or more CKDu risk factors. Moreover, several geographic areas with CKDu risk factor clusters had no reported work-related CKD. These areas represent new industries and sectors to be monitored for possible future increases of CKDu cases.

National health policies and strategies for addressing chronic kidney disease: Data from the International Society of Nephrology Global Kidney Health Atlas

National strategies for addressing chronic kidney disease (CKD) are crucial to improving kidney health. We sought to describe country-level variations in non-communicable disease (NCD) strategies and CKD-specific policies across different regions and income levels worldwide. The International Society of Nephrology Global Kidney Health Atlas (GKHA) was a multinational cross-sectional survey conducted between July and October 2018. Responses from key opinion leaders in each country regarding national NCD strategies, the presence and scope of CKD-specific policies, and government recognition of CKD as a health priority were described overall and according to region and income level. 160 countries participated in the GKHA survey, comprising 97.8% of the world's population. Seventy-four (47%) countries had an established national NCD strategy, and 53 (34%) countries reported the existence of CKD-specific policies, with substantial variation across regions and income levels. Where CKD-specific policies existed, non-dialysis CKD care was variably addressed. 79 (51%) countries identified government recognition of CKD as a health priority. Low- and low-middle income countries were less likely to have strategies and policies for addressing CKD and have governments which recognise it as a health priority. The existence of CKD-specific policies, and a national NCD strategy more broadly, varied substantially across different regions around the world but was overall suboptimal, with major discrepancies between the burden of CKD in many countries and governmental recognition of CKD as a health priority. Greater recognition of CKD within national health policy is critical to improving kidney healthcare globally.

Safety of Stromal Vascular Fraction Cell Therapy for Chronic Kidney Disease of Unknown Cause (Mesoamerican Nephropathy)

Chronic kidney disease of unknown cause (CKDu), also known as Mesoamerican nephropathy, typically presents as an ischemic nephropathy with chronic tubulointerstitial fibrosis in normotensive patients, rapidly progressing to kidney failure. In this first-in-human, open-label, safety study, we followed 18 patients with CKDu (stages 3-5) for 36 months after receiving a single infusion of angiogenic/anti-fibrotic autologous adipose-derived stromal vascular fraction (SVF) cells into their kidneys bilaterally via renal artery catheterization. SVF therapy was safe and well tolerated. There were no SVF-related serious adverse events and no procedural complications. Color Doppler evaluation at 2 months demonstrated increased perfusion to the interlobar and/or arcuate artery levels in each kidney evaluated (36/36) with a reduction in resistance index at the hilar artery (35/36) kidneys. Beyond 12 months, patients with initial eGFR <30 mL/minute/1.73 m2 deteriorated, whereas those ≥30 mL/minute/1.73 m2 further sustained their renal function, suggesting a possible renal protective effect in that group.