Chronic kidney disease of unknown etiology in Sri Lanka

Emerging Roles of Xanthine Oxidoreductase in Chronic Kidney Disease

Xanthine Oxidoreductase (XOR) is a ubiquitous, essential enzyme responsible for the terminal steps of purine catabolism, ultimately producing uric acid that is eliminated by the kidneys. XOR is also a physiological source of superoxide ion, hydrogen peroxide, and nitric oxide, which can function as second messengers in the activation of various physiological pathways, as well as contribute to the development and the progression of chronic conditions including kidney diseases, which are increasing in prevalence worldwide. XOR activity can promote oxidative distress, endothelial dysfunction, and inflammation through the biological effects of reactive oxygen species; nitric oxide and uric acid are the major products of XOR activity. However, the complex relationship of these reactions in disease settings has long been debated, and the environmental influences and genetics remain largely unknown. In this review, we give an overview of the biochemistry, biology, environmental, and current clinical impact of XOR in the kidney. Finally, we highlight recent genetic studies linking XOR and risk for kidney disease, igniting enthusiasm for future biomarker development and novel therapeutic approaches targeting XOR.

Environmental fluoride exposure and implications on potential pediatric kidney health risks: an approach with urinary biomarkers

BACKGROUND

Environmental fluoride exposure at elevated levels is potentially linked to kidney injury, and may contribute to chronic kidney disease of uncertain etiology (CKDu) as a risk factor. However, this link remains unclear, and examining the risk of kidney damage from early life fluoride exposure may provide important insights. Hence, this study aimed to investigate associations of fluoride exposure with pediatric kidney health in CKDu impacted and unimpacted communities in Sri Lanka.

METHODS

Considering the geographical variations in environmental fluoride, climate, and prevalence of CKDu, four study groups were established within selected education zones in CKDu-endemic dry zone regions (D-En), and CKDu-nonendemic regions within the dry (D-NE), wet (W-NE), and intermediate (I-NE) climatic zones. The study population included 922 school students (11-18 years of age). Participants in each group were divided into four subgroups based on quartiles of respective urinary fluoride (UF) distribution for comparison of urinary kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and albumin-creatinine ratio (ACR).

RESULTS

UF levels in participants particularly in CKDu endemic dry zone regions were significantly high compared to the other regions. Significantly high median urinary NGAL (in D-NE) and ACR (in D-EN, and W-NE) levels were observed in subgroups of higher UF quartiles. Albuminuria was not particularly identified in subjects with high UF excretion. Urinary KIM-1 showed no significant variation across the UF quartile subgroups. Linear regression identified weak associations of UF with kidney injury biomarkers.

CONCLUSIONS

Fluoride exposure is particularly high in CKDu-endemic dry zone communities. As implied by kidney injury biomarkers, a strong link between fluoride exposure and pediatric kidney health was not evident at the observed exposure levels in the study regions.

Clinico-Epidemiological Profile of Patients with Chronic Kidney Diseases of Unknown Etiology: A Hospital-Based, Cross-Sectional Study from Central India

Background

Chronic kidney disease (CKD) not associated with known risk factors, called CKD of unknown etiology (CKDu), has been reported from several geographically distinct regions across the world. This study reports the clinical and epidemiological profile of patients with CKDu from a new hotspot in central India.

Materials and Methods

This cross-sectional study describes the sociodemographic, clinical, and laboratory profile of the patients diagnosed with CKDu visiting a tertiary care public hospital in the state of Chhattisgarh in central India between June 2019 and June 2021. CKDu was diagnosed as progressive CKD, minimal proteinuria, absence of hematuria, diabetes, severe hypertension, systemic illness, glomerulonephritis or other urinary tract diseases, and presence of symmetrically contracted kidneyon ultrasound.

Results

A total of 166 (3.1%) out of 5365 patients with CKD were diagnosed with CKDu. The mean age was 53.6 ± 11.8 years. The patients were predominantly male (n = 113, 68.1%), belonged to rural areas (n = 147, 88.6%), and were engaged in farming (n = 105, 63.3%). The estimated glomerular filtration rate (eGFR) at presentation was 21.5 ± 15.1 ml/min/1.73m2. Forty-four (26.5%) had stage 3 CKD, 57 (34.3%) had stage 4 CKD, and 65 (39.2%) had stage5 CKD. There was an over-representation of CKDu cases in patients with CKD from Gariyaband (36.0%) and Mahasamund (25%) districts of Chhattisgarh and Nuapada (35.0%) and Balangir (30.0%) districts of Odisha.

Conclusion

The study suggests clustering of cases of CKDu in certain districts of Orissa and Chhattisgarh.

Food-mediated exposure of Hofmeister ions in Oryza sativa (Rice) from selected CKDu endemic regions in Sri Lanka

The objectives of this study were to determine selected Hofmeister anions and cations that are important for kidney health, in raw rice samples from selected Chronic Kidney Disease of unknown etiology (CKDu) endemic and non-endemic areas in Sri Lanka and their intake. The anions and cations were analyzed by Ion Chromatography and Microwave Plasma Atomic Emission Spectrometry (MP-AES), respectively, after alkaline and acid digestion in thirty raw rice samples each from CKDu endemic and non-endemic areas, and the dietary intake was estimated. The mean concentrations of fluoride (F-), chloride (Cl-), phosphate (PO43-), sulfate (SO42-), sodium (Na+), magnesium (Mg2+), potassium (K+), and calcium (Ca2+) in raw rice in CKDu endemic areas were 53.317, 1515.3, 2799.6, 2704.9, 30.603, 300.76, 1001.3, and 90.075 mg/kg, respectively. The mean concentration of the anions and cations in raw rice from CKDu non-endemic areas were 22.850, 947.52, 4418.7, 6080.2, 23.862, 364.45, 955.78, and 96.780 mg/kg, respectively. Significantly higher differences (p < 0.05) were reported in the mean concentration of F-, Cl-, and Na+ in raw rice from CKDu endemic areas in comparison with the samples from non-endemic areas. The aggregated estimated daily intake (EDI) and cumulative EDI of F- via consumption of cooked non-traditional samba rice from CKDu endemic areas for adults were the highest (0.155 and 0.172 mg/kg bw/d, respectively), which were higher than the recommended tolerable upper intake value (0.15-0.2 mg/kg bw/d). In contrast, the traditional rice from CKDu non-endemic areas for adolescents, reported the lowest values (0.0210 and 0.0470 mg/kg bw/d, respectively). Adults who consume non-traditional samba rice from CKDu endemic areas were at health risk, while children were the most vulnerable group due to their low body weight. These results indicate that the consumption of rice rich in Hofmeister ions may contribute to the total intake and act as risk factors to negatively affect weak kidneys in CKDu endemic areas. Further research to analyze Hofmeister ions in cooked rice and rice from different countries is recommended.

Identifying Serum Metabolites and Gut Bacterial Species Associated with Nephrotoxicity Caused by Arsenic and Fluoride Exposure

Co-contamination of arsenic (As) and fluoride (F) is widely distributed in groundwater, which are known risk factors for the nephrotoxicity. Emerging evidence has linked environmentally associated nephrotoxicity with the disturbance of gut microbiota and blood metabolites. In this study, we generated gut microbiota and blood metabolomic profile and identified multiple serum metabolites and gut bacteria species, which were associated with kidney injury on rat model exposed to As and F alone or combined. Combined As and F exposure significantly increased creatinine level. Abnormal autophagosomes and lysosome were observed, and the autophagic genes were enhanced in kidney tissue after single and combined As and F exposure. The metabolome data showed that single and combined As and F exposure remarkably altered the serum metabolites associated with the proximal tubule reabsorption function pathway, with glutamine and alpha-ketoglutarate level decreased in all exposed group. Furthermore, phosphatidylethanolamine (PE), the key contributor of autophagosomes, was decreased significantly in As and F + As exposed groups during the screen of autophagy-animal pathway. Multiple altered gut bacterial microbiota at phylum and species levels post As and F exposure were associated with targeted kidney injury, including p_Bacteroidetes, s_Chromohalobacter_unclassified, s_Halomonas_unclassified, s_Ignatzschineria_unclassified, s_Bacillus_subtilis, and s_Brevundimonas_sp._NA6. Meanwhile, our analysis indicated that As and F co-exposure possessed an interactive influence on gut microbiota. In conclusion, single or combined As and F exposure leads to the disruption of serum metabolic and gut microbiota profiles. Multiple metabolites and bacterial species are identified and associated with nephrotoxicity, which have potential to be developed as biomarkers of As and/or F-induced kidney damage.

Sugarcane ash and sugarcane ash-derived silica nanoparticles alter cellular metabolism in human proximal tubular kidney cells

Multiple epidemics of chronic kidney disease of an unknown etiology (CKDu) have emerged in agricultural communities around the world. Many factors have been posited as potential contributors, but a primary cause has yet to be identified and the disease is considered likely multifactorial. Sugarcane workers are largely impacted by disease leading to the hypothesis that exposure to sugarcane ash produced during the burning and harvest of sugarcane could contribute to CKDu. Estimated exposure levels of particles under 10 μm (PM10) have been found to be exceptionally high during this process, exceeding 100 μg/m3 during sugarcane cutting and averaging ∼1800 μg/m3 during pre-harvest burns. Sugarcane stalks consist of ∼80% amorphous silica and generate nano-sized silica particles (∼200 nm) following burning. A human proximal convoluted tubule (PCT) cell line was subjected to treatments ranging in concentration from 0.025 μg/mL to 25 μg/mL of sugarcane ash, desilicated sugarcane ash, sugarcane ash-derived silica nanoparticles (SAD SiNPs) or manufactured pristine 200 nm silica nanoparticles. The combination of heat stress and sugarcane ash exposure on PCT cell responses was also assessed. Following 6-48 h of exposure, mitochondrial activity and viability were found to be significantly reduced when exposed to SAD SiNPs at concentrations 2.5 μg/mL or higher. Oxygen consumption rate (OCR) and pH changes suggested significant alteration to cellular metabolism across treatments as early as 6 h following exposure. SAD SiNPs were found to inhibit mitochondrial function, reduce ATP generation, increase reliance on glycolysis, and reduce glycolytic reserve. Metabolomic analysis revealed several cellular energetics pathways (e.g., fatty acid metabolism, glycolysis, and TCA cycle) are significantly altered across ash-based treatments. Heat stress did not influence these responses. Such changes indicate that exposure to sugarcane ash and its derivatives can promote mitochondrial dysfunction and disrupt metabolic activity of human PCT cells.

Prevalence of kidney disease of unknown etiology in agricultural workers, Guatemala

Objectives

To determine the prevalence of kidney disease of unknown etiology in banana, melon, and tomato workers in north-eastern Guatemala, and to evaluate the usefulness of a cystatin C blood test for early detection of renal disease.

Methods

This was a cross-sectional, farm-based study of 462 agricultural workers conducted from June to September 2021. Epidemiological and demographic characteristics of the workers were collected through a self-administered questionnaire. Blood samples were obtained to determine glucose, creatinine and cystatin C levels. Anthropometric and clinical data were also recorded.

Results

The prevalence of kidney disease of unknown etiology was 3.03% (95% confidence interval (CI): 1.36-4.70%) based on glomerular filtration rate (GFR-EPI) < 60 mL/min/1.73 m², with a significantly higher prevalence in banana workers (5.67%; 95% CI: 2.16-9.18%) than melon workers (p = 0.009) and tomato workers (p = 0.044). Ten workers (2.16%) had reduced kidney function (GFR-EPI 60-90 mL/min/1.73 m²). The levels of cystatin C showed less variability (coefficient of variation 46.4%) than those of creatinine (coefficient of variation 67.0%), and cystatin C levels in cases with abnormal and reduced kidney function were significantly different from cases with normal kidney function (p < 0.001).

Conclusions

Surveillance of the health of active farm workers and improvement of working conditions, such as sun protection, adequate hydration, and sufficient breaks, are recommended. The significant differences in cystatin C levels between cases with abnormal and reduced kidney function and those with normal kidney function suggest that cystatin C could be a useful measure for early detection of renal disease.

Rising of a global silent killer: critical analysis of chronic kidney disease of uncertain aetiology (CKDu) worldwide and mitigation steps

Chronic kidney disease of uncertain aetiology (CKDu) is an advanced version of chronic kidney disease (CKD) which bears a high burden on the world health economy. More than 200 articles were analysed to understand the disease responsible for more than 30,000 deaths per year. CKDu is a non-communicable occupational disease that has a progressive deterioration of the kidney in the absence of CKD risk factors such as hypertension, diabetes and glomerulonephritis, while the diagnosis is only possible at the later stages when kidney function is no longer effective. Published evidence for the existence of CKDu was found for around 35 countries. This is a growing health issue in Asia, Central America, Africa and Middle East with identified hot spots. Despite many research studies over decades, the exact root causes are still uncertain. Six main suspected causative factors are identified. Those are heat stress, strenuous labour, dehydration, use of agrochemicals, exposure to heavy metals and the use of polluted water and agricultural lands. This review summarizes four key areas which are CKDu and its general medical background, worldwide prevalence, suspected causative factors and potential circumventing steps to mitigate against CKDu. The importance of further studies addressing early detection and surveillance methods, contribution of nephrotoxins in environmental health, soil chemistry on transporting nephrotoxins, geological parameters which influence the prevalence of the disease and other related sectors to overcome the mysterious nature is highlighted. Mitigation steps to lessen the burden of CKDu are also identified.

Impact of Leisure Activities on the Well-being of Elders: Evidence from Sri Lanka

Sri Lanka demonstrates the most rapid aging process among countries in South Asia. The high prevalence of non-communicable diseases (NCDs) in the meanwhile results in more than 70% of deaths in the population, a factor that would curtail leisure activities of elders significantly. The objective of this study was to investigate the engagement of elders in leisure activities in Sri Lanka, and to examine the relationship between leisure activities and their well-being. The study was conducted in 2018 in a rural district of Sri Lanka adopting a mixed methods approach. Simple random sampling technique was used to select the respondents aged between 55 and 74 years, and face-to-face interviews were conducted with 300 respondents. Qualitative data was also collected from ten key informants while a few observations were also made on selected activities of elders in the study area. The research found that a two-thirds of the surveyed respondents were suffering from NCDs, showing a clear impact on their leisure activities. The presence of leisure activities was much lower among NCD affected elders (48%) compared to NCD free elders (80%). The majority of respondents possess sufficient and accurate knowledge on how to prevent NCDs, but they rarely practiced it. Leisure activities were significantly higher among males (75%) compared to females (43%). Males participated in leisure activities such as, gardening/agriculture etc. (99%), while females were engaged in religious activities such as visiting such places and meditation (98%). Leisure engagement demonstrated a positive impact on their life satisfaction. Although a sizable proportion of elders was engaged in leisure activities, analysis of both qualitative and quantitative data supported the view that the intensity of activities may not be helpful to maintain good health. Life satisfaction and well-being of elders are crucial for rapidly aging Sri Lankan society. Motivating elders and others, including school children, via strengthening of related policies and programs would reduce the NCD burden and enable present and future elders to enjoy a more fulfilling life in old age.

Endosulfan induced kidney cell injury by modulating ACE2 through up-regulating miR-429 in HK-2 cells

Endosulfan, a typical organochlorine pesticide, is widely used in agricultural countries and was detected in blood samples from the general population. Studies have shown a positive correlation between chronic kidney disease of unknown aetiology (CKDu) and endosulfan. CKDu has become endemic in agricultural countries, with clinical manifestations of tubulointerstitial fibrosis.The goal of this study was to investigate the effects of endosulfan in kidney cell injury in human renal tubular epithelial cells (HK-2), focusing on apoptosis, inflammatory response, and epithelial-mesenchymal transition (EMT). We found that endosulfan induced apoptosis in HK-2 cells by up-regulating the expression of BAX, APAF-1, Caspase-3 and mitochondrial Cytochrome c was released into the cytosol. Endosulfan caused an inflammatory response, showing the increase in the secretion and mRNA expression levels of IL-6/IL-8. Endosulfan triggered EMT, characterized by downregulation of E-cadherin and upregulation of Vimentin. Western blot results showed that p-Smad3 and Smad3 protein expression were elevated while the expression of Smad7 were decreased in endosulfan-exposed groups. Dual luciferase reporter assay confirmed the potential binding capacity of miR-429 to 3'-UTR of ACE2. Endosulfan causes upregulation of miR-429 and downregulation of ACE2 in HK-2 cells. Overexpression of miR-429 or silencing of ACE2 in HK-2 cells caused apoptosis, inflammation and EMT through TGF signaling pathway. These findings suggest that endosulfan can lead to kidney cell injury by modulating ACE2 through up-regulating miR-429, providing new evidence for the pathogenesis of CKDu.

Intake of fluoride and other Hofmeister ions from black tea consumption in CKDu prevalent areas, Sri Lanka

Dietary exposure of selected Hofmeister ions-fluoride, chloride, sulfate, phosphate, sodium, potassium, magnesium, and calcium from black tea consumption in chronic kidney disease of unknown etiology (CKDu) prevalent areas in Sri Lanka-were assessed in order to understand exposure and risk. Black tea samples (n = 25) were collected from CKDu prevalent areas and control areas (n = 15). Total fluoride content in alkali fused digested black tea samples was determined. The available Hofmeister ions in tea infusions prepared using deionized water and the groundwater collected by CKDu endemic areas were compared. Dietary exposure was calculated by chronic daily intake data. Total fluoride concentrations ranged from 80 to 269 mg/kg in tea collected from the CKDu endemic regions and 62.5-123.5 mg/kg in non-endemic regions. The fluoride content in infusions ranged from 1.45 to 2.04 mg/L in CKDu endemic areas and 1.11-1.38 mg/L in control samples. The infusions prepared with local groundwater from the CKDu endemic areas showed an elevated level of fluoride 95% than that of the infusion prepared using same tea with deionized water. Aggregated chronic daily intake value from tea and groundwater exceeds the estimated adequate daily intake value of fluoride. The hazard quotient (HQ) values of fluoride in 5 min and 120 min tea infusions were 1.60 and 2.20, respectively, and indicate an adverse health risk. Potassium content in tea infusions collected from CKDu endemic areas is higher than in the control. Even though these values are less than the adequate intake, it may pose an impairment on a weak kidney. Chronic daily intake of Hofmeister ions, i.e., fluoride and potassium from black tea consumed in CKDu endemic areas may induce a risk for CKDu.

Hemoglobin Levels Among Male Agricultural Workers: Analyses From the Demographic and Health Surveys to Investigate a Marker for Chronic Kidney Disease of Uncertain Etiology

OBJECTIVE

Estimate agricultural work's effect on hemoglobin (Hgb) level in men. A negative effect may indicate presence of chronic kidney disease of uncertain etiology.

METHODS

We use Demographic and Health Surveys data from seven African and Asian countries and use matching to control for seven confounders.

RESULTS

On average, Hgb levels were 0.09 g/dL lower among agricultural workers compared with matched controls. Significant effects were observed in Ethiopia, India, Lesotho, and Senegal, with effects from 0.07 to 0.30 g/dL lower Hgb level among agricultural workers. The findings were robust to multiple control groups and a modest amount of unmeasured confounding.

CONCLUSIONS

Men engaged in agricultural work in four of the seven countries studied have modestly lower Hgb levels. Our data support integrating kidney function assessments within Demographic and Health Surveys and other population-based surveys.

The geo-spatial perspective of biological, social and environmental determinants of early pregnancy anaemia in rural Sri Lanka: Need for context-specific approaches on prevention

We provide a novel approach to understanding the multiple causations of maternal anaemia in a geospatial context, highlighting how genetics, environment and socioeconomic disparities at the micro-geographical level lead to the inequitable distribution of anaemia. All first-trimester pregnant women registered for the antenatal care programme in Anuradhapura District, Sri Lanka from July to September 2019 were invited to the Rajarata Pregnancy Cohort (RaPCo), which assessed the prevalence of anaemia in early pregnancy. The combination of the prevalence of anaemia and minor haemoglobinopathy-related anaemia (MHA) with the poverty headcount index of the 22 health divisions in the district was investigated using GeoDa spatial K-means clustering. Sociodemographic and economic data at the divisional level were compared between identified clusters. Combining the analysis with the geographical and environmental characteristics of the region, further hypotheses regarding anaemia in this community were formulated. The study included data from 3,137 pregnant women in early pregnancy. The anaemia and MHA prevalence varied from 13.6 to 21.7% and from 2.6% to 5%, respectively. We identified four distinct spatial clusters. The cluster with the highest anaemia prevalence also included high poverty and the highest prevalence of MHA. The clusters had significant differences with regard to ethnic distribution, access to water, sanitation and dietary patterns. Areas supplied by major irrigation projects had significantly low levels of anaemia, probably attributable to internal migration and improved livelihood. It was evident that genetic, socioeconomic and environmental risk factors were grouped at the divisional level, and that their complex interactions make controlling anaemia with blanket interventions unsuccessful. Analysis of the distribution of heterogeneous risk factors at the micro-geospatial level helped identify context-specific approaches to tackle anaemia in pregnancy.

Social, political and legal determinants of kidney health: Perspectives from lower- and middle-income countries with a focus on India

The social determinants of health (SDoH) are the non-medical factors that influence kidney health outcomes directly or indirectly in a substantial manner and include conditions in which people are born, grow, work, live, and age. Many such challenges in lower- and middle- income countries have an unfavourable impact on kidney health. These conditions potentially influence economic policies and systems, development agendas, social norms, social policies, and political systems. In addition, many political and legal factors also determine and modify the ultimate outcome in patients with kidney disease. Legal factors that ensure universal health care, promote gender and racial equality, prevent malpractices and regulate strict laws in the field of kidney transplantation are the paramount determinants for the provision of necessary kidney care. Converging lines of evidence have supported the impact of social variables such as socioeconomic resources, social inclusion, housing conditions, educational attainment, and financial status on kidney health, particularly affect vulnerable and disadvantaged groups and result in challenges in kidney care delivery. Furthermore, the climate is an important SDoH that plays a crucial role in the occurrence, prevalence, and progression of kidney diseases as highlighted by the presence of higher prevalence of chronic kidney disease in hot tropical countries. The rising incidence of water and vector-borne diseases causing acute kidney injury is another consequence of disruptive environmental and climate change which is detrimental to kidney health. Political risk factors such as conflict also have a devastating influence on kidney health. The relationship between SDoH and kidney health outcomes requires more clarity. Gaps in the current knowledge need to be identified to inform the development of appropriate interventions to address upstream socio-economic risk factors for kidney disease.

Where do you live and what do you do? Two questions that might impact your kidney health

In many cases the social determinants of health need to be assessed through their interaction with environmental factors. This review looks at the impact of physical location and occupation of individuals on their kidney health. It examines the effect of living at high altitude on kidney function and the relationship between extreme cold or hot temperatures and the incidence of kidney injury. It reviews as well the many occupations that have been linked to kidney disease in high-income and low-and-middle-income countries. As a conclusion, this overview proposes preventive recommendations that could be individualized based on weather, altitude, socio-economic level of the country and occupation of the individual.

The position of geochemical variables as causal co-factors of diseases of unknown aetiology

Abstract

The term diseases of unknown aetiology (DUA) or idiopathic diseases is used to describe diseases that are of uncertain or unknown cause or origin. Among plausible geoenvironmental co-factors in causation of DUA, this article focusses on the entry of trace elements, including metals and metalloids into humans, and their involvement in humoral and cellular immune responses, representing potentially toxic agents with implications as co-factors for certain DUA. Several trace elements/metals/metalloids (micronutrients) play vital roles as co-factors for essential enzymes and antioxidant molecules, thus, conferring protection against disease. However, inborn errors of trace element/metal/metalloid metabolisms can occur to produce toxicity, such as when there are basic defects in the element transport mechanism. Ultimately, it is the amount of trace element, metal or metalloid that is taken up, its mode of accumulation in human tissues, and related geomedical attributes such as the chemical form and bioavailability that decisively determine whether the exerted effects are toxic or beneficial. Several case descriptions of DUA that are common worldwide are given to illustrate our knowledge so far of how trace element/metal/metalloid interactions in the immune system may engender its dysregulation and be implicated as causal co-factors of DUA.

Article highlights

The importance of a proper understanding of geochemical perturbations in human metabolisms is emphasisedIt is proferred that such an understanding would aid greatly in the decipherment of diseases of unknown aetiology (DUA)The thesis presented may pave the way towards better diagnosis and therapy of DUA.

Factors Associated with Symptom Burden in Adults with Chronic Kidney Disease Undergoing Hemodialysis: A Prospective Study

People with end stage renal disease and undergoing hemodialysis experience a high symptom burden that impairs quality of life. This study aimed to assess the prevalence, dynamicity and determinants of symptom burden among middle-aged and older adult hemodialysis patients. A descriptive cross-sectional study together with a longitudinal assessment was used. A total of 118 and 102 hemodialysis patients were assessed at baseline and at a 6-month follow-up. Validated questionnaires were used to assess the symptom burden, stress, illness perception and social support. Multiple linear regression analysis was used to determine the factors associated with symptom burden. The median number of symptoms experienced was 21 (Interquartile Range (IQR); 18−23) and 19 (IQR; 13−22) at baseline and 6 months, respectively. Having elevated stress (β = 0.65, p ≤ 0.005) and illness perception (β = 0.21, p = 0.02) were significantly predicted symptom burden at baseline (F (4, 112) = 55.29, p < 0.005, R2 = 0.664). Stress (β = 0.28, p = 0.003), illness perception (β = 0.2, p = 0.03), poor social support (β = −0.22, p = 0.01) and low body weight (β = −0.19, p = 0.03) were the determinants for symptom burden at 6 months (F (5, 93) = 4.85, p ≤ 0.005, R2 = 0.24). Elevated stress, illness perception level, poor social support and low post-dialysis body weight were found to be determinants for symptom burden. Attention should be given to psychosocial factors of hemodialysis patients while conducting assessment and delivering care to patients.

A review of molecular mechanisms linked to potential renal injury agents in tropical rural farming communities

The chronic kidney disease of unknown etiology (CKDu) is a global health concern primarily impacting tropical farming communities. Although the precise etiology is debated, CKDu is associated with environmental exposures including heat stress and chemical contaminants such as fluoride, heavy metals, and herbicide glyphosate. However, a comprehensive synthesis is lacking on molecular networks underpinning renal damage induced by these factors. Addressing this gap, here we present key molecular events associated with heat and chemical exposures. We identified that caspase activation and lipid peroxidation are common endpoints of glyphosate exposure, while vasopressin and polyol pathways are associated with heat stress and dehydration. Heavy metal exposure is shown to induce lipid peroxidation and endoplasmic reticulum stress from ROS activated MAPK, NFĸB, and caspase. Collectively, we identify that environmental exposure induced increased cellular oxidative stress as a common mechanism mediating renal cell inflammation, apoptosis, and necrosis, likely contributing to CKDu initiation and progression.

Kidney Function in Rice Workers Exposed to Heat and Dehydration in Costa Rica

The aim of this study was to evaluate heat exposure, dehydration, and kidney function in rice workers over the course of three months, in Guanacaste, Costa Rica. We collected biological and questionnaire data across a three-month-period in male field (n = 27) and other (n = 45) workers from a rice company where chronic kidney disease of unknown origin (CKDu) is endemic. We used stepwise forward regression to determine variables associated with estimated glomerular filtration rate eGFR at enrollment and/or change in eGFR, and Poisson regression to assess associations with incident kidney injury (IKI) over the course of three months. Participants were 20−62 years old (median = 40 in both groups). Dehydration was common (≥37%) in both groups, particularly among other workers at enrollment, but field workers were more exposed to heat and had higher workloads. Low eGFR (<60 mL/min/1.73 m2) was more prevalent in field workers at enrollment (19% vs. 4%) and follow-up (26% vs. 7%). Field workers experienced incident kidney injury (IKI) more frequently than other workers: 26% versus 2%, respectively. Age (β = −0.71, 95%CI: −1.1, −0.4), current position as a field worker (β = −2.75, 95%CI: −6.49, 0.99) and past work in construction (β = 3.8, 95%CI: −0.1, 7.6) were included in the multivariate regression model to explain eGFR at enrollment. The multivariate regression model for decreased in eGFR over three month included current field worker (β = −3.9, 95%CI: −8.2, 0.4), current smoking (β= −6.2, 95%CI: −13.7−1.3), dehydration (USG ≥ 1.025) at both visits (β= −3.19, 95%CI: −7.6, 1.2) and pain medication at follow-up (β= −3.2, 95%CI: −8.2, 1.95). Current fieldwork [IR (incidence rate) = 2.2, 95%CI 1.1, 5.8) and being diabetic (IR = 1.8, 95%CI 0.9, 3.6) were associated with IKI. Low eGFR was common in field workers from a rice company in Guanacaste, and being a field worker was a risk factor for IKI, consistent with the hypothesis that occupational heat exposure is a critical risk factor for CKDu in Mesoamerica.

The Indian Chronic Kidney Disease (ICKD) study: baseline characteristics

Background

Chronic kidney disease (CKD) is an important cause of morbidity and mortality worldwide. There is a lack of information on epidemiology and progression of CKD in low–middle income countries. The Indian Chronic Kidney Disease (ICKD) study aims to identify factors that associate with CKD progression, and development of kidney failure and cardiovascular disease (CVD) in Indian patients with CKD.

Methods

ICKD study is prospective, multicentric cohort study enrolling patients with estimated glomerular filtration rate (eGFR) 15–60 mL/min/1.73 m², or >60 mL/min/1.73 m² with proteinuria. Clinical details and biological samples are collected at annual visits. We analysed the baseline characteristics including socio-demographic details, risk factors, disease characteristics and laboratory measurements. In addition, we compared characteristics between urban and rural participants.

Results

A total of 4056 patients have been enrolled up to 31 March 2020. The mean ± SD age was 50.3 ± 11.8 years, 67.2% were males, two-thirds of patients lived in rural areas and the median eGFR was 40 mL/min/1.73 m². About 87% were hypertensive, 37% had diabetes, 22% had CVD, 6.7% had past history of acute kidney injury and 23% reported prior use of alternative drugs. Diabetic kidney disease, chronic interstitial nephritis (CIN) and CKD-cause unknown (CKDu) were the leading causes. Rural participants had more occupational exposure and tobacco use but lower educational status and income. CIN and unknown categories were leading causes in rural participants.

Conclusions

The ICKD study is the only large cohort study of patients with mild-to-moderate CKD in a lower middle income country. Baseline characteristics of study population reveal differences as compared with other cohorts from high-income countries.

Chronic Kidney Disease of Uncertain Etiology in Sri Lanka: Curing between Medicine and Traditional Culture

Chronic Kidney Disease of unknown origin (CKDu) has appeared across Sri Lanka’s North Central Province (NCP) since the 1990s as an epidemic, unexplained by conventional associated risk factors. During the past few decades, a large number of studies attempted to determine the unknown etiology of CKDu. Despite these investigations, no concrete conclusions were developed, though a number of contradictory hypotheses emerged. The present ethnographic study was carried out in two endemic areas, labelled as “CKDu hotspots”, and illuminates how curing takes place between biomedicine and traditional cultural practices. Our ethnographic study thoroughly scrutinized three decades of lived experience, lay-perceptions and local discourses on CKDu. We used a qualitative study design with a transcendental phenomenological approach and employed a mixture of ethnographic methods. Data collection techniques included participant observation, in-depth interviews, focus group discussions and key informant interviews. Data was analysed by using an interpretive thematic analysis model. Findings revealed that lay people have constructed a popular discourse on CKDu, and we explored their views on the origin, etiology and prevalence of CKDu in their locality over the past few decades. Patients’ narratives revealed that there were currently a number of gaps in service delivery. These were mainly due to distant relationships between healthcare providers and CKDu patients. Lay people in affected communities were marginalized throughout the investigation process to determine the unknown etiology, their involvement marginalized to merely acting as objects for scientific instigation. The affected communities strongly believed that CKDu was a recent phenomenon resulting from the mismanagement of the natural environment due to social and lifestyle changes. These findings highlight local dynamics of healthcare seeking behaviours which demand complementary medicine system, particularly given the number of limitations in the biomedical system. Empirical evidence generated from this study suggests a conceptual shift to an ethno-medical model to address CKDu. Improving cultural competency and communication skills among healthcare providers in public health are crucial in order to apply a “bio-psychosocial perspective” in healthcare delivery system and bridging the gap between hospital and the community.

Urinary concentrations of neonicotinoid insecticides were related to renal tubular dysfunction and neuropsychological complaints in Dry-zone of Sri Lanka

Neonicotinoids are systemic insecticides used since the 1990’s , that possess renal tubular toxicity. We conducted a field-based descriptive study in the North Central Dry-zone of Sri Lanka, where chronic kidney disease (CKD) of unknown etiology has been increasing since the 1990’s. To elucidate the relationship between renal tubular dysfunctions and urinary neonicotinoids concentrations, we collected spot urine samples from15 CKD patients, 15 family members, and 62 neighbors in 2015, analyzed two renal tubular biomarkers, Cystatin-C and L-FABP, quantified seven neonicotinoids and a metabolite N-desmethyl-acetamiprid by LC–MS/MS; and we investigated their symptoms using a questionnaire. Cystatin-C and L-FABP had a positive correlation (p < 0.001). N-Desmethyl-acetamiprid was detected in 92.4% of the urine samples, followed by dinotefuran (17.4%), thiamethoxam (17.4%), clothianidin (9.8%), thiacloprid and imidacloprid. Dinotefuran and thiacloprid have never been registered in Sri Lanka. In High Cystatin-C group (> 70 μg/gCre, n = 7), higher urinary concentration of dinotefuran (p = 0.009), and in Zero Cystatin-C group (< LOQ, n = 7), higher N-desmethyl-acetamiprid (p = 0.013), dinotefuran (p = 0.049), and thiacloprid (p = 0.035), and more complaints of chest pains, stomachache, skin eruption and diarrhea (p < 0.05) were found than in Normal Cystatin-C group (n = 78). Urinary neonicotinoids may be one of the potential risk factors for renal tubular dysfunction in this area.

Risk factors for endemic chronic kidney disease of unknown etiology in Sri Lanka: Retrospect of water security in the dry zone

The prevalence of chronic kidney disease of unknown etiology (CKDu) is receiving considerable attention due to the serious threat to human health throughout the world. However, the roles of geo-socio-environmental factors in the prevalence of the CKDu endemic areas are still unknown. Sri Lanka is one of the countries most seriously affected by CKDu, where 10 out of 25 districts have been identified as the areas with the high prevalence of CKDu (10-20%). This review summarizes the geographical distribution of CKDu and its probable geochemical, behavioral, sociological, and environmental risk factors based on research related to hydrogeochemical influences on CKDu in Sri Lanka. More than 98% of CKDu patients have consumed groundwater as their primary water source in daily life, indicating the interactions of geogenic contaminants (such as F^-, total dissolved solids, Hofmeister ions) in groundwater is responsible for the disease. Apart from the hydrogeochemical factors, mycotoxins, cyanotoxins, use of some herbal medicines, dehydration, and exposure to agrochemicals were alleged as risk factors. Sociological factors, including poverty, living habits and anthropogenic activities, may also provoke the emergence of CKDu. Therefore, the interaction of geo-socio environmental risk factors should be sociologically and scientifically considered to prevent the prevalence of CKDu. Future in-depth studies are required to reveal the individual role of each of the postulated etiological factors, possibly using machine learning and advanced statistics.

Two decades of chronic kidney disease of unknown aetiology (CKDu) research: Existing evidence and persistent gaps from epidemiological studies in Sri Lanka

BACKGROUND

Chronic Kidney Disease of unknown origin (CKDu) excludes known primary renal conditions or systemic disease (such as diabetes mellitus or hypertension). Prominence of CKDu has been noted for some decades in Sri Lanka, especially among men in particular rural areas, prompting many studies directed towards environmental causation. This article critically reviews relevant primary studies.

METHODS

Articles for this literature review (n = 86) were found by searching Medline, Embase, Global Health and ProQuest databases over 2000-2020 utilizing a standard algorithm. Articles were critiqued according to criteria for diagnosis of CKDu, aetiological agents investigated, analytic methods employed and findings.

RESULTS

Criteria for diagnosis of CKDu varied significantly, including pre-selection by proteinuria, eGFR and biopsy proven interstitial nephritis. Prevalence studies have been largely conducted in the North Central Province, with recent studies demonstrating the presence of CKDu in other regions. Aetiological factors investigated in primary studies included water source, use of agrochemicals, agricultural work, heavy metals, snake bites, ayurvedic medication, heat stress, infectious diseases and usage of tobacco and betel leaf. There is no conclusive evidence for any one aetiological agent despite consistent evidence of distal factors such as male sex, rural residence and farming.

CONCLUSIONS

The current body of evidence for any aetiological agent as the cause of CKDu in Sri Lanka is limited. Further research with stronger study designs is necessary to increase knowledge of aetiology of CKDu in Sri Lanka to identify and eliminate exposure to possible causative agent(s) prior to concluding that the disease is multifactorial.

The Groundwater Geochemistry and the Human Health Risk Assessment of Drinking Water in an Area with a High Prevalence of Chronic Kidney Disease of Unknown Etiology (CKDu), Sri Lanka

Chronic kidney disease of unknown etiology (CKDu) has become an alarming health issue in Sri Lanka. The disease is more notable among farming communities and people who consume groundwater as their main source of drinking water. To assess the possible links between drinking water chemistry and expansion of CKDu, the study was compared with hydrogeochemical data of drinking water sources in a CKDu prevalent area (Girandurukotte GND, Badulla District) and a reference area (Dambethalawa GND, Ampara District) in Sri Lanka. Based on the results, nephrotoxic heavy metal (Cd, Cr, Pb, and As) concentrations were significantly higher in the CKDu prevalent site than the reference area, compromised the harmful consequences to the people in the CKDu hotspot. Results of the inverse distance weighted (IDW) interpolation tool indicated the nephrotoxic heavy metals contents including Cd, Pb, As, and Cr in CKDu hotspot were changed in the ranges of 9.78–187.25 μg/L, 0.08–0.66 μg/L, 20.76–103.30 μg/L, and 0.03–0.34 μg/L. The random distribution patterns were shown by the result in Moran’s index values. Noteworthy, the results have emphasized a strong association between fluoride and water hardness. The frequency of occurrence above the threshold limit of fluoride was 28% in non-CKDu water samples, while 81% in CKDu prevalent sites. The hardness values in the CKDu prevalent site indicated “moderately hard water,” while the non-CKDu area indicated the “soft water.” Furthermore, this paper quantified overall water quality and heavy metal contamination and assessed the human health risks associated with drinking water. According to the results of the water quality index, 90% of the samples in the CKDu prevalent area were classified as “poor water” and “very poor water” for drinking purposes, while 73.33% of the samples in the non-CKDu area were “good” and “excellent” for drinking usage. Calculated chronic daily intake (CDIoral) and hazard quotient (HQoral) of nephrotoxicants were higher in CKDu hotspot than the non-CKDu site. Besides, the hazard index (HI) values obtained for the CKDu prevalent area exceeding the acceptable limit (HI = 1) indicated potential health risks to the people in those areas. This study suggests that long-term exposure to nephrotoxic heavy metals, water hardness, and fluoride present in drinking water may threaten human health and affect kidney functions. Therefore, regular monitoring and better management of water supplies in CKDu prevalent areas are essential to determine the contamination load and reduce the health impacts due to excessive and long-term exposure to the nephrotoxicants.

Association of Pesticides and Kidney Function among Adults in the US Population 2001-2010

Chronic kidney disease of unknown cause is prevalent in a range of communities; however, its etiology remains unclear. We examined the association between pesticide exposures and the risk of kidney function loss using four waves of the National Health and Nutrition Examination Survey (NHANES) to identify a pathological pathway. We pooled data from four cross-sectional waves of NHANES, with 41,847 participants in total. Exposure to malathion increased the risk of low kidney function (aOR = 1.26, 95% CI = 1.01-1.56) in the adjusted model. Increased risk of low kidney function was not found among those exposed to 2,4-D (aOR = 0.88, 95% CI = 0.72-1.09), 3,5,6-trichloropyridinol (aOR = 0.96, 95% CI = 0.83-1.12), and 3-PBA (aOR = 1.03, 95% CI = 0.94-1.13). Our findings provide evidence of altered kidney function in people exposed to malathion, highlighting the potential of organophosphate pesticides' role in renal injury.

Involvement of mitochondrial fission in renal tubular pyroptosis in mice exposed to high and environmental levels of glyphosate combined with hard water

Chronic interstitial nephritis in agricultural communities (CINAC) has reached epidemic proportions. The combination of glyphosate and hard water has been postulated to play a potent aetiological role in CINAC. Therefore, dynamin-related protein 1 (Drp1)-mediated aberrant mitochondrial fission and subsequent activation of the nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (Nlrp3)/caspase1 pathway may be involved in the pathogenesis of nephropathy. In the present study, mice were sub-chronically exposed to high doses and environmental levels of glyphosate (100 mg/kg body weight (mg/kg·bw) glyphosate in Roundup and 0.7 mg/L pure glyphosate, respectively) and hard water (2500 mg/L CaCO3 and 250 mg/L Ca2+, respectively) in drinking water. Moreover, Mdivi-1 (Md-1, 10 mg/kg·bw) was intraperitoneally injected to inhibit Drp1 on the basis of the high-dose experiment. Histopathological examination, biochemical analysis, ELISA, western blotting and fluorescent staining were used to analyse renal structure, renal tubular pyroptosis and mitochondrial fission/fusion alterations. The results showed dramatic proximal tubular injury, particularly in the combined groups. Moreover, significant increases in the protein expression levels of calmodulin (CaM), calmodulin-dependent protein kinase II (CaMKII), Drp1/p-Drp1-Ser616 and the Txnip/Nlrp3/caspase1 signalling pathway, and alterations in oxidative stress were observed in the combined groups, and these effects were attenuated by the Drp1 inhibitor Md-1. Intriguingly, there may be a synergistic effect of glyphosate and hard water on renal injury. Taken together, these results suggest that the combination of glyphosate and hard water, even at environmental exposure levels, enhances pyroptosis and ongoing tubulointerstitial inflammation through excessive Drp1-mediated mitochondrial fission.

Groundwater as a potential cause of Chronic Kidney Disease of unknown etiology (CKDu) in Sri Lanka: a review

The cause of Chronic Kidney Disease of unknown etiology (CKDu) in the rural dry zone of Sri Lanka remains unidentified, despite vast research efforts that brought about an extensive list of potential risk factors. Among these, the long-term exposure to various nephrotoxic elements through drinking groundwater was widely suspected owing to the unique geographical distribution of the disease. This review focuses on such well-known hypotheses suspecting the relations with fluoride, hardness, major ions, heavy metals, metalloids, organic matter, agrochemical residues, pathogens, and bacterial toxins in the groundwaters of the CKDu-endemic region. It was comprehensively discussed why each of these constituents was considered a risk factor of CKDu, how could they possibly trigger the pathogenesis of the disease, what was the evidence that supported or failed each hypothesis, and whether providing safe drinking water had been effective at mitigating the progression of the disease. Although plenty of circumstantial evidence supported an etiology related to groundwater for CKDu, it was impossible to elucidate the cause-effect relationships between drinking impaired groundwater and the occurrence of the disease. Future research should be effectively designed to clarify the role of groundwater in the onset of CKDu by taking into account the gaps in past research.

Prevalence, risk factors and predicted risk of cardiac events in chronic kidney disease of uncertain aetiology in Sri Lanka: A tubular interstitial nephropathy

Cardiovascular disease (CVD) is the leading cause of morbidity and mortality in patients with 'traditional' chronic kidney disease (CKD). However, chronic kidney disease of uncertain aetiology (CKDu), a tubular interstitial nephropathy is typically minimally proteinuric without high rates of associated hypertension or vascular disease and it is unknown if the rates of CVD are similar. This study aimed to identify the prevalence and the risk of CVD in patients with CKDu. This cross-sectional study included patients with confirmed CKDu who were attending two renal clinics in CKDu endemic-area. A detailed medical history, blood pressure, electrocardiogram (resting and six minutes vigorous walking), echocardiograms, appropriate laboratory parameters and medical record reviews were used to collect data at baseline. The WHO/Pan American Health Organization, cardiovascular risk calculator was employed to determine the future risk of CVD. The clinics had recorded 132 number of patients with CKDu, of these 119 consented to participation in the study. The mean age was 52 (± 9.5) years and mean eGFR was 51.1 (± 27.61); a majority (81.5% (n = 97)) were males. Thirty-four patients (28.6%) had evidence of ischaemic heart disease (IHD). Troponin-I (p = 0.02), Age >50 years (p = 0.01) and hyperuricemia (p = 0.01) were significantly associated with IHD in CKDu. Left ventricular hypertrophy was reported in 20.2% (n = 24). According to the risk calculator, 97% of the enrolled patients were at low risk (<10%) for experiencing a cardiovascular event within the next 10 years. Patients with CKDu have low prevalence and risk for CVD, implying that a majority are likely to survive to reach end-stage kidney disease. Our findings highlight the need for developing strategies to minimize the progression of CKDu to end-stage renal disease.

A pilot case-control study using a one health approach to evaluate behavioral, environmental, and occupational risk factors for chronic kidney disease of unknown etiology in Sri Lanka

BACKGROUND

Chronic kidney disease of unknown etiology (CKDu) was first recognized in Sri Lanka in the early 1990s, and since then it has reached epidemic levels in the North Central Province of the country. The prevalence of CKDu is reportedly highest among communities that engage in chena and paddy farming, which is most often practiced in the dry zone including the North Central and East Central Provinces of Sri Lanka. Previous studies have suggested varied hypotheses for the etiology of CKDu; however, there is not yet a consensus on the primary risk factors, possibly due to disparate study designs, sample populations, and methodologies.

METHODS

The goal of this pilot case-control study was to evaluate the relationships between key demographic, cultural, and occupational variables as risk factors for CKDu, with a primary interest in pesticide exposure both occupationally and through its potential use as an ingredient in brewed kasippu alcohol. An extensive one health focused survey was developed with in cooperation with the Centre for Research, Education, and Training on Kidney Diseases of Sri Lanka.

RESULTS

A total of 56 CKDu cases and 54 control individuals were surveyed using a proctored, self-reported questionnaire. Occupational pesticide exposure and alcohol consumption were not found to be significant risk factors for CKDu. However, a statistically significant association with CKDu was observed with chewing betel (adjusted odds ratio [aOR]: 6.11, 95% confidence interval [CI]: 1.93, 19.35), age (aOR: 1.07, 95% CI: 1.02, 1.13), owning a pet dog (aOR: 3.74, 95% CI: 1.38, 10.11), water treatment (aOR: 3.68, 95% CI: 1.09, 12.43) and pests in the house (aOR: 5.81, 95% CI: 1.56, 21.60).

CONCLUSIONS

The findings of this study suggest future research should focus on practices associated with chewing betel, potential animal interactions including pests in the home and pets, and risk factors associated with water.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s42522-020-00034-3.

Epidemiological evidence from south Indian working population-the heat exposures and health linkage

Changing climate and rising temperatures are predicted to affect millions of workers due to heat stress risks, especially in tropical settings. We used a cross-sectional study design to profile the heat exposures of ~1500 workers from eight-industrial sectors using a QuesTemp wet bulb globe temperature (WBGT) monitor, quantified the heat-strain indicators viz., rise in Core Body Temperature (CBT), Sweat Rate (SwR), and Urine Specific Gravity (USG) by standard methods and evaluated the health impacts of heat stress using a structured questionnaire. Heat exposures (Avg.WBGT: 28.4 ± 2.6 °C) exceeded the Threshold Limit Value (TLV) for 70% of workers and was significantly associated with the rise in CBT >1 °C in 11.3% and elevated USG >1.020 in 10.5% of the workers. The heat-exposed workers had 2.3 times higher odds of reporting adverse health outcomes (84%) compared to the unexposed workers (95% CI: 1.74-3.19; p value ≤ 0.0001). Mild reduction in kidney function observed in 49% of salt - pan workers, and a high prevalence of kidney stones (33%) among the 91 steelworkers subjected to kidney ultrasound had a significant association with chronic high WBGT exposure above the TLV (p value < 0.034). Further, in-depth assessments are warranted to develop strategies for interventions and protective labor policies to avert adverse occupational health and productivity consequences for millions of workers globally, especially in the rising temperature scenario.

Risk Assessment of Trace Element Contamination in Drinking Water and Agricultural Soil: A Study in Selected Chronic Kidney Disease of Unknown Etiology (CKDu) Endemic Areas in Sri Lanka

Unexplained or unclear etiology of chronic kidney disease (CKDu) has been reported in Sri Lanka’s North Central Province (NCP) for more than two decades. Meanwhile, high exposure to heavy metals/metalloids and their accumulation are recognized as the origin of many acute and chronic diseases in certain vulnerable human tissues including kidneys. This study evaluates the contamination status of heavy metals/metalloids of the drinking water and agricultural soil in two CKDu endemic areas compared with a reference area in Sri Lanka based on common indexes and attribute of the commonly used fertilizers evaluated to identify the basic sources of toxic metals in the agricultural soil. Mean concentrations of heavy metals/metalloids such as Mn, Co, As, Cd, Pb, Cu, Zn, and Fe in drinking water of CKDu endemic areas were far below Sri Lankan water quality standards (permissible limits). In addition, all sampling locations dropped below the medium range of the heavy metal pollution index of water (HPI 15–40). Geoaccumulation indexes (Igeo) of soil reveal that paddy soil in CKDu endemic areas is being moderately polluted with toxic metals/metalloids such as As, Pb, Cu, Ni, Cr, Zn, and Cd. On the other hand, the application of fertilizers, which contained a high dose of toxic metals, could be the driving force for agricultural soil pollution, and limitless application of low-quality fertilizer would lead to more soil contamination with heavy metals. Hence, hazardous metals can be incorporated into the food chains via contaminated paddy soil.

Balkan Endemic Nephropathy: An Autopsy Case Report

Balkan endemic nephropathy (BEN) is a form of interstitial nephritis seen only in certain geographical areas in the Balkan peninsula. Herein we describe the gross and histological changes in a diseased 42-year-old male Caucasian patient with BEN. All the changes fit the classically described alterations, with copper hue discoloration of the skin of the torso and orange discoloration of the soles and palms. Grossly, the kidneys were atrophic, with the left one weighing 31 grams and the right one 32 grams. Their surface was predominantly smooth with areas of fine granulations and cystic transformations. Histology revealed hyalinization of the glomeruli, predominantly in the external part of the cortex, severe vascular changes, interstitial fibrosis, and scant inflammatory cell infiltrate. The renal pelvis and ureters revealed multiple urothelial papillomas and atypical urothelial hyperplasia. BEN is only one geographical variant of interstitial nephritis caused by exposure to aristolochic acid. Other forms of this condition include Chinese herb nephropathy/aristolochic acid nephropathy, as well as several similar endemic conditions with a yet unestablished link to aristolochic acid.

A comparative review: Chronic Kidney Disease of unknown etiology (CKDu) research conducted in Latin America versus Asia

INTRODUCTION

The incidence of chronic kidney disease of unknown or uncertain etiology (CKDu) is recognized as a global non-communicable health crisis. The goal of this work is to compare the types of research studies in Latin America and Asia, two regions with increasing CKDu incidence.

METHODS

A comparative literature review was conducted to evaluate the CKDu research design for peer-reviewed articles published from 2015 to 2019. Full texts were reviewed to identify study location, study type, study design, risk factors evaluated, and if applicable, sample type and number.

RESULTS

In Asia and Latin America, 82 and 65 articles were identified in total, respectively, with 55 field studies in Asia versus 34 in Latin America. In Asia, research was focused on drinking water (34), heavy metals (20), and agrochemical product usage (19) as potential risk factors. In Latin America, research focused mostly on heat stress/dehydration (36) and agrochemical product usage (18) as potential CKDu risk factors. Biological samples were collected more frequently than environmental samples, especially in Latin America.

DISCUSSION

Research to pinpoint the risk factors associated with CKDu to date is not standardized and typically limited in geographical scope. The emphasis of CKDu research varies by geographic region, with a greater priority placed on water quality and chemical exposure in Asia, versus dehydration and heat stress in Latin America. Using a harmonized approach to CKDu research would yield improved understanding of the risk factors associated with CKDu and how they compare across affected regions.

Renal tubular injury induced by glyphosate combined with hard water: the role of cytosolic phospholipase A2

Background

The combined effects of glyphosate and hard water on chronic kidney disease of unknown etiology (CDKu) have attracted much interest, but the mechanisms remain unknown. Cytoplasmic phospholipase A₂ (cPLA₂) plays a key role in the acute and chronic inflammatory reactions. This study explored the effect of glyphosate combined with hard water on renal tubules and the possible targets and mechanisms involved.

Methods

In vivo experiments were conducted to investigate the synergistic effects and potential mechanisms of glyphosate and hard water on renal tubular injury in mice.

Results

Administration of glyphosate in mice resulted in elevated levels of β2-microglobulin (β₂-MG), albumin (ALB), and serum creatinine (SCr) compared to control mice. This increase was more pronounce when glyphosate was combined with hard water. In the glyphosate-treated mice, small areas of the kidney revealed fibroblast proliferation and vacuolar degeneration, particularly at the higher dose of 400 mg/kg glyphosate. However, the combination of glyphosate and hard water induced an even greater degree of pathological changes in the kidney. Immunofluorescence and western blot analyses showed that glyphosate and hard water had a coordinated effect on calcium ions (Ca²⁺)-activated phospholipase A₂ and the activation may play a key role in inflammation and renal tubular injury. Exposure to glyphosate alone or glyphosate plus hard water increased the levels of oxidative stress markers and inflammatory biomarkers, namely, thromboxane A₂ (TX-A₂), leukotriene B₄ (LTB₄), prostaglandin E₂ (PGE₂), nitric oxide synthase (NOS), and nitric oxide (NO). Parameters of oxidative stress, including the levels of superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were decreased. Further analysis showed that the levels of these biomarkers were significantly different between the mice treated with glyphosate plus hard water and the mice treated with glyphosate alone.

Conclusions

These findings suggested that hard water combined with glyphosate can induce renal tubular injury in mice, and this may involve mitogen-activated protein kinases (MAPK)/cytosolic phospholipase A₂ (cPLA₂)/arachidonic acid (AA) and its downstream factors.

Progression of potential etiologies of the chronic kidney disease of unknown etiology in Sri Lanka

Chronic kidney disease of unknown etiology (CKDu) is a major health issue in agricultural areas in Sri Lanka. Despite many attempts to identifying causative factors of CKDu, the real cause/s remain/s elusive to date. Understanding the progression of potential etiologies may provide valuable insight into this quest. Literature relevant to CKDu addresses several etiologies, including quality of drinking water in the affected areas including hardness, fluoride, ionicity, agrochemical and heavy metal contaminations, consumption of contaminated food, and the genetic makeup of vulnerable populations. Progression of the etiologies revealed persistent interest in heavy metals of multiple origins: waterborne, foodborne, or soilborne. Secondary factors, such as water hardness, fluoride, and ionicity appear to act synergistically, aggravating the role of heavy metals on the onset, and the progression of CKDu. Demographical factors, such as male sex, over 50 years of age, agriculture-related occupation, and the consumption of contaminated water and food are intricately related with the disease progression while other minor risk factors such as smoking, alcohol consumption, etc. exasperate the disease condition. Since, none of these etiologies are examined adequately, conducting laboratory exposure studies under in-vivo and in-vitro settings to understand their role in CKDu is crucial.

Purposeful Review to Identify Risk Factors, Epidemiology, Clinical Features, Treatment and Prevention of Chronic Kidney Disease of Unknown Etiology

The global burden of chronic kidney disease (CKD) has risen, and chronic kidney disease of unknown etiology (CKDu) contributes considerably to the national burden of CKD. It is characterized by irreversible, slowly advancing disease, and symptoms often appear in the late stages of the disease. It is a serious, novel cause of kidney failure and leads to premature deaths. Many hypotheses have emerged; however, the etiology of CKDu continues to be elusive and debatable and it is claimed that the etiology is multifactorial, encompassing environmental, genetic, occupational, and social factors. The dominant histopathological feature is chronic tubulointerstitial nephritis. It predominantly affects individuals with low socio-economic status, of working age, largely without chronic comorbidities, who perform strenuous labor in extreme conditions in various tropical areas of the world. It is often fatal due to fast progression and limited access to dialysis or transplant options in the involved geographic areas. Early recognition and appropriate interventions at the earliest possible stage are imperative for decreasing its associated morbidity and mortality. In this review, I tried to summarize available evidence on the risk factors, epidemiology, clinical features, treatment, and prevention of CKDu. The literature search for this review was conducted comprehensively by using different electronic databases and by using appropriate search terms.

Kidney developmental effects of metal-herbicide mixtures: Implications for chronic kidney disease of unknown etiology

Chronic kidney disease of unknown etiology (CKDu) is an emerging global concern affecting several agricultural communities in the Americas and South Asia. Environmental contaminants such as heavy metals (e.g., Cd, As, Pb, and V) and organic pesticides (e.g., glyphosate) in the drinking water have been hypothesized to play a role in childhood onset and progression of this disease. However, a comprehensive analysis of chemical contaminants in the drinking water and effects of these compounds and their mixtures on kidney development and function remains unknown. Here, we conducted targeted and non-targeted chemical analyses of sediment and drinking water in CKDu affected regions in Sri Lanka, one of the most affected countries. Using zebrafish Danio rerio, a toxicology and kidney disease model, we then examined kidney developmental effects of exposure to (i) environmentally derived samples from CKDu endemic and non-endemic regions and (ii) Cd, As, V, Pb, and glyphosate as individual compounds and in mixtures. We found that drinking water is contaminated with various organic chemicals including nephrotoxic compounds as well as heavy metals, but at levels considered safe for drinking. Histological studies and gene expression analyses examining markers of kidney development (pax2a) and kidney injury (kim1) showed novel metal and glyphosate-metal mixture specific effects on kidney development. Mitochondrial dysfunction is directly linked to kidney failure, and examination of mixture specific mitochondrial toxicity showed altered mitochondrial function following treatment with environmental samples from endemic regions. Collectively, we show that metals in drinking water, even at safe levels, can impede kidney development at an early age, potentiating increased susceptibility to other agrochemicals such as glyphosate. Drinking water contaminant effects on mitochondria can further contribute to progression of kidney dysfunction and our mitochondrial assay may help identify regions at risk of CKDu.

Exploring the Root Cause for Chronic Kidney Disease of Unknown Etiology (CKDu) via Analysis of Metal Ion and Counterion Contaminants in Drinking Water: A Study in Sri Lanka

The introduction of elevated amounts of foreign ions into the blood may lead to impairment of the filtration membrane of kidneys and chronic kidney damage. In order to assess the risk of consumption of drinking water (dug well water) in chronic kidney disease of unknown etiology (CKDu), affected areas in Sri Lanka, trace metals, and other counterions in water samples obtained from dug wells were analyzed and compared with a reference area. Drinking water could be the major source that is responsible for entering nephrotoxic ion contaminants into the human body. To achieve the objective, drinking water samples were collected from dug wells in two CKDu endemic areas and a reference area where no CKDu patients were found in a dry season. In the Wewelketiya area (one of the endemic areas), Cd concentrations in 60% of water samples and Pb concentrations in 40% of water samples have exceeded the maximum limit given by Sri Lanka water quality standards. Fluoride concentrations also have exceeded the permissible limits of more than 80% of collected water samples in both CKDu endemic areas. However, none of the water samples in reference areas has reported that Cd, Pb, and fluoride are beyond their maximum permissible limits. Hence, people in the particular CKDu endemic areas are at risk of kidney tissue damage due to long-term exposure to drinking water with elevated levels of some metal ions and counterions.

Novel antihypertensive action of rutin is mediated via inhibition of angiotensin converting enzyme/mineralocorticoid receptor/angiotensin 2 type 1 receptor (ATR1) signaling pathways in uninephrectomized hypertensive rats

Hypertension is the most common cardiovascular disease that affects approximately 26% of adult population, worldwide. Rutin is one of the important flavonoids that is consumed in the daily diet, and found in many food items, vegetables, and beverages. Uninephrectomy (UNX) of the left kidney was performed, followed by induction of hypertension. The rats were randomly divided into four groups of 10 rats: group 1-Sham-operated rats; group 2-UNX rats, group 3-UNX-L-NAME (40 mg/kg) plus rutin (100 mg/kg bwt), and groups 4-UNX-L-NAME plus lisinopril (10 mg/kg bwt), orally for 3 weeks. Results revealed significant heightening of arterial pressure and oxidative stress indices, while hypertensive rats treated with rutin had lower expressions of angiotensin converting enzyme (ACE) and mineralocorticoid receptor in uninephrectomized rats. Together, rutin as a novel antihypertensive flavonoid could provide an unimaginable benefits for the management of hypertension through inhibition of angiotensin converting enzyme and mineralocorticoid receptor. PRACTICAL APPLICATIONS: Hypertension has been reported to be the most common cardiovascular disease, affecting approximately 26% of the adult population worldwide with predicted prevalence to increase by 60% by 2025. Recent advances in phytomedicine have shown flavonoids to be very helpful in the treatment of many diseases. Flavonoids have been used in the treatment and management of cardiovascular diseases, obesity and hypertension. The study revealed that rutin, a known flavonoid inhibited angiotensin converting enzyme (ACE), angiotensin 2 type 1 receptor (ATR1), and mineralocorticoid receptor (MCR), comparable to the classic ACE inhibitor, Lisinopril, indicating the novel antihypertensive property of rutin. Therefore, flavonoids such as rutin found in fruits and vegetables could, therefore, serve as an antihypertensive drug regimen. Combining all, functional foods rich in flavonoids could be used as potential therapeutic candidates for managing uninephrectomized hypertensive patients.

Environmental and Occupational Risk Factors Associated with Chronic Kidney Disease of Unknown Etiology in West Javanese Rice Farmers, Indonesia

Chronic kidney disease of unknown etiology (CKDu) in agricultural population is an increasing issue. This study aims to obtain a prevalence estimate of CKDu in male rice farmers in West Java, Indonesia; and analyze the relationship between CKDu and environmental and occupational factors. The study design was cross-sectional. This study included 354 healthy male farmers in two rice agriculture areas in West Java with different altitudes (low altitude and high-altitude location). This research included blood and urine sampling from the farmers for serum creatinine (SCr) level and proteinuria; questionnaire on demographic information, occupational factors and other risk factors for CKDu. We measured ambient temperature and humidity in both study locations for environmental factors. From SCr level and proteinuria, we categorized the farmers into five stages of CKD; then we distinguished CKDu from CKD if the farmers had stage 1-4 of CKD but without diabetes, hypertension and other traditional causes. Data were analyzed with multivariate logistic regression to get prevalence odd ratios of CKDu and its relationship with environmental and occupational factors, adjusted with other risk factors of CKDu. The overall prevalence of CKD was 24.9% and CKDu was 18.6%. For the environmental factors, farm location (high altitude versus low altitude location) was associated with CKDu (Prevalence Odds Ratio (POR): 2.0; 95% CI: 1.2-3.5). For the occupational factors, although not significant, the risk of CKDu increased with the longer use of insecticide and with the more frequent of insecticide use. We suggested that there was a need to conduct future research to investigate more on the association of those environmental and occupational factors with CKDu.

Quality of Life and Symptom Burden among Chronic Kidney Disease of Uncertain Etiology (CKDu) Patients in Girandurukotte, Sri Lanka

Symptom burden and health-related quality of life (HRQOL) are important predictors of how a disease affects patients' lives, especially for endemic health problems such as chronic kidney disease of uncertain etiology (CKDu). Our study describes symptom burden, HRQOL, and associated demographic and clinical variables in CKDu patients in the Girandurukotte area, Sri Lanka. A cross-sectional study included 120 CKDu patients attending the renal clinic in the endemic area. The instruments applied were the Kidney Disease Quality of Life-Short Form (KDQOL-SFTM) version 1.3 and CKD Symptom Index-Sri Lanka. Socio-demographic, disease-related, and anthropometric variables were also investigated. The mean age of patients was 61.87 (SD 11.31), while 69.2% were male. The mean glomerular filtration rate was 28.17 (SD 14.03) mL/min/1.73 min2, and 70.8% were anemic. Bone/joint pain was the most experienced symptom while the median number of symptoms reported by patients was 5 (IQR 3-7). The mean symptom burden, physical component summary, mental component summary, and kidney-disease-specific component scores were 12.71 (SD 10.45), 68.63 (SD 19.58), 78.53 (SD 18.78), and 81.57 (SD 5.86), respectively. Age was found to be a significant predictor of HRQOL, while hemoglobin level and being a farmer were significant predictors of symptom burden. Our data indicate that CKDu patients in all stages experience at least one symptom affecting all aspects of HRQOL.

Trust, Conflict, and Engagement in Occupational Health: North American Epidemiologists Conduct Occupational Study in Communities Affected by Chronic Kidney Disease of Unknown Origin (CKDu)

PURPOSE OF REVIEW

Science has been used as a tool of colonialism, and aspects of science privilege researchers in the global North (USA and Europe). The environmental justice and worker health movements in the USA and globally have influenced aspects of how occupational and environmental health research is conceived and conducted so that it is more equitable. This review provides a case example of research in the area of chronic kidney disease of unknown origin (CKDu).

RECENT FINDINGS

In the present work, the author describes aspects of community-based participatory research and anti-colonial research that influence a current occupational epidemiology study of CKDu in Mesoamerica among workers in agriculture and non-agricultural industries. The research includes investigators from numerous countries in the global North and South and funding from the US government and corporations. The role of industry in science and the misuse of science by corporate interests remain substantial threats to research integrity. The ability of researchers to navigate potentially conflicting interests with industry and workers, and establish trust within and outside the scientific community, is essential for sustained engagement in longitudinal studies. Trust is about human relationships. It takes time and effort to build and is essential for creating equitable, empowering research relationships.

Sri Lanka: report on its children's environmental health

Sri Lanka is an island country located in the Indian Ocean, characterized by tropical weather, with an estimated population of 21.4 million in 2017, one third of them being children. Advancing and rapidly changing technology, novel industries, consumer goods and equipment have introduced new health hazards of a chemical, biological and physical nature to future generations. The infant mortality rate has declined to around 8-9 per 100,000 since 2015. Congenital malformations were the most significant cause of neonatal death. Thus, there might be unproven environmental factors which affect infant mortality rates despite robust field and hospital services. Air pollution is a major environmental health hazard to children, largely due to hazardous industries, vehicular emissions and traditional cooking stoves. The health of children living in urban households and attending schools in cities is adversely affected by air pollution. Usage of polythene and plastic for toys, utensils, bags, lunch sheets and other daily essentials leads to overusage and improper waste management and open burning. This emits dioxins, which are carcinogens, hormone disruptors, and which can be transferred to the fetus via the placenta. In rural areas, the burning of agricultural waste and certain agro-forestry activities have also led to air pollution. Indoor air pollution (IAP) remains a large threat as 66% of the population use biomass for cooking. Use of inefficient stoves and biomass, poor ventilation and absence of chimneys, contribute to IAP. Other indoor air pollutants such as tobacco smoke, volatile organic compounds, asbestos, pesticides, kerosene, mercury, mosquito coils and biological pollutants also prevail. Biological pollutants, such as dust mites, droppings and urine from pets, insects and rodents, pollen from indoor plants and outdoor air, and fungi, including moulds in poorly maintained buildings, can trigger asthma or cause allergic reactions and infections among children inhabiting these environments. In rural areas, chemicals were accountable for 30.2% of acute poisonings, with kerosene oil being the most common cause, followed by paracetamol. More than 80% of agricultural workers in the country work in the informal sector with limited personal protective equipment use, while pesticide usage is increasing. Children who engage in agriculture-related work and hazardous industries are at risk of developing health consequences at early stages. Dengue remains a major environmental health problem as the reduction of mosquito breeding sites has been a challenging task for many years. It is essential to gain more evidence of existing environmental risk factors and their associations with the health of children. Information dissemination among local and international experts on Children's Environmental Health (CEH) issues needs to be enhanced and properly established. Training programs should be conducted for healthcare workers to update their knowledge. Pediatricians are needed for remote hospitals and primary healthcare centers. Environmental parameters and biological parameters are not routinely monitored in most of the hazardous environments.

Biochemical and histopathological changes in Wistar rats after consumption of boiled and un-boiled water from high and low disease prevalent areas for chronic kidney disease of unknown etiology (CKDu) in north Central Province (NCP) and its comparison with low disease prevalent Colombo, Sri Lanka

BACKGROUND

Chronic Kidney Disease of unknown etiology (CKDu) is prevalent in North Central Province (NCP) of Sri Lanka. Consumption of un-boiled dug well water has been identified as one of the causative factors. This in-vivo study was performed to investigate some of the suspected factors associated with the pathogenesis of CKDu mediated via ground water.

METHOD

Rats were given water, collected from high and low disease prevalent areas from the NCP of Sri Lanka and the results compared with those obtained from previously identified low disease prevalent area; Colombo. Blood Urea Nitrogen, creatinine, urinary microalbumin:creatinine ratio together with ALT and AST levels were analyzed and results were compared using one-way ANOVA and paired t-Test. Histopathology was analyzed using non-parametric method.

RESULTS

Rats that ingested water from New Town Medirigiriya (NTM) from high disease prevalent NCP reported significantly elevated microalbumin:creatinine ratios compared to other water sources after 8 months, whilst boiled water from NTM had been able to significantly reduce it. Histopathological findings after the 14 months experimental period revealed significantly high tubular lesion index in rats that ingested water from NCP compared to Colombo. Rats that ingested water from high disease prevalent Divuldamana (DD) from NCP showed the highest kidney lesion index though the fluoride content was relatively low in this area compared to other water sources from high disease prevalent NCP. Rats that ingested boiled and un-boiled water from NTM also developed severe lesions whilst the group from Colombo reported the lowest. Low disease prevalent area from NCP, Huruluwewa (HW) also reported elevated liver enzymes and altered renal histopathology. Association of Na⁺:Ca²⁺ ratio in the disease progression was not reflected by the current study. Compared to Colombo, high fluoride, calcium and sodium contents were observed in water from high disease prevalent areas. All the water samples were negative for heavy metals.

CONCLUSIONS

Though Fluoride is a known kidney toxic agent it cannot be the sole reason for CKDu in NCP, Sri Lanka. Various toxic elements present in NCP water may contribute to different grade of kidney and liver lesions in Wistar rats.

Assessment of Nutritional Status and Dietary Pattern of a Rural Adult Population in Dry Zone, Sri Lanka

The objective of this work was to describe average dietary intake, physical activity (PA) and nutritional status of the adult population of Girandurukotte, Sri Lanka. A cross-sectional survey, including one 24-h dietary recall, international physical activity questionnaire and anthropometric measurements was conducted in a representative sample of 120 adults. Mean (SD) for body mass index (BMI), waist circumference (WC), waist to hip ratio (WHR) and waist to height ratio (WHtR) were 23.06(4.20) kg/m2, 85.6(9.5) cm, 0.95(0.05) and 0.55(0.07), respectively. Significant differences were observed in height, body fat %, body muscle %, hip circumference, WHR, WHtR, fat mass index and hand grip strength between men and women (p < 0.05). Among the study group, 35.8% were overweight, 13.3% were obese and 11.7% were underweight. Central obesity was observed in 59.2%, 97.5% and 74.2% of adults by WC, WHR and WHtR, respectively. Mean (SD) dietary diversity score and dietary diversity score with portions were 4.77(1.28) and 4.09(1.32), respectively. Mean daily intake of protein, fruits, vegetables and dairy were well below the national recommendations. Despite the higher PA level, nearly half the population was overweight and obese and the majority was centrally obese. None of the dietary diversity scores met the optimal levels, suggesting poor quality and quantity of the diet.

Prevalence of chronic kidney disease in Sri Lanka: A profile of affected districts reliant on groundwater

This analysis provides new estimates of chronic kidney disease (CKD) prevalence - including CKD of unknown etiology (CKDu) - across ten districts most affected by CKD in Sri Lanka, including an examination of rural households' historical reliance on groundwater consumption. A carefully designed household survey provides information on whether these households self-reported having a member in the decade prior to 2018, who had been clinically diagnosed with CKD. Households were classified according to whether or not they had used groundwater (from household wells, agro-wells or springs) as their primary source for drinking or cooking for at least five years between 1999 and 2018. More than 98% of households reported having consumed groundwater as their primary source of drinking or cooking water for at least five of those years and >15% of households reported having at least one CKD-affected member in the ten-year period up to 2018, but these numbers varied across and within districts. The reported characteristics of symptomatic individuals reveal that the incidence of CKD was significantly higher among females (62%) than males (38%). In addition to CKD, about 63% of symptomatic individuals had hypertension and about one-third of them also had diabetes. About 33% of the symptomatic individuals had neither diabetes nor hypertension, where this group most closely fits commonly used definitions of CKDu. With a survey response of over 8000 households comprising as many as 30,000 individuals, these data illustrate the scale of CKD in the most-affected districts of Sri Lanka on an aggregate basis as well as revealing differences across districts and at the sub-district level.

Regional variation in chronic kidney disease and associated factors in hypertensive individuals in rural South Asia: findings from control of blood pressure and risk attenuation-Bangladesh, Pakistan and Sri Lanka

BACKGROUND

We aimed to determine the prevalence of chronic kidney disease (CKD) and its cross-country variation among hypertensive individuals in rural Bangladesh, Pakistan and Sri Lanka. We also explored the factors associated with CKD in these populations.

METHOD

We studied baseline data from the Control of Blood Pressure and Risk Attenuation-Bangladesh, Pakistan and Sri Lanka (COBRA-BPS) trial, an ongoing cluster randomized controlled trial on 2643 hypertensive adults ≥40 years of age from 30 randomly selected rural clusters, 10 in each of the three countries. CKD was defined as an estimated glomerular filtration rate (eGFR) <60 mL/min/1.73 m2 or a urine albumin:creatinine ratio (UACR)  ≥30 mg/g. Determinants for CKD were assessed using logistic regression analysis.

RESULTS

The overall prevalence of CKD was 38.1% (95% confidence interval 36.2-40.1%): 21.5% with eGFR <60 mL/min/1.73 m2 and 24.4% with UACR ≥30 mg/g. CKD prevalence varied across the three countries (58.3% in Sri Lanka, 36.4% Bangladesh and 16.9% Pakistan; P <0.001). The factors independently associated with higher odds of CKD were older age, being unmarried, higher 24-h urinary sodium excretion, presence of diabetes, elevated systolic blood pressure, diuretic use and living in Bangladesh or Sri Lanka (versus Pakistan).

CONCLUSIONS

The prevalence of CKD is alarmingly high in community-dwelling hypertensive adults, with significant cross-country variation in South Asia. Our findings underscore the urgency for further research into the etiology of CKD and address associated factors in targeted public health strategies with hypertension care outreach services in rural South Asia.

CLINICALTRIALS.GOV

NCT02657746.

Rationale and population-based prospective cohort protocol for the disadvantaged populations at risk of decline in eGFR (CO-DEGREE)

INTRODUCTION

A recently recognised form of chronic kidney disease (CKD) of unknown origin (CKDu) is afflicting communities, mostly in rural areas in several regions of the world. Prevalence studies are being conducted in a number of countries, using a standardised protocol, to estimate the distribution of estimated glomerular filtration rate (eGFR), and thus identify communities with a high prevalence of reduced glomerular filtration rate (GFR). In this paper, we propose a standardised minimum protocol for cohort studies in high-risk communities aimed at investigating the incidence of, and risk factors for, early kidney dysfunction.

METHODS AND ANALYSIS

This generic cohort protocol provides the information to establish a prospective population-based cohort study in low-income settings with a high prevalence of CKDu. This involves a baseline survey that included key elements from the DEGREE survey (eg, using the previously published DEGREE methodology) of a population-representative sample, and subsequent follow-up visits in young adults (without a pre-existing diagnosis of CKD (eGFR<60 mL/min/1.73m2), proteinuria or risk factors for CKD at baseline) over several years. Each visit involves a core questionnaire, and collection and storage of biological samples. Local capacity to measure serum creatinine will be required so that immediate feedback on kidney function can be provided to participants. After completion of follow-up, repeat measures of creatinine should be conducted in a central laboratory, using reference standards traceable to isotope dilution mass spectrometry (IDMS) quality control material to quantify the main outcome of eGFR decline over time, alongside a description of the early evolution of disease and risk factors for eGFR decline.

ETHICS AND DISSEMINATION

Ethical approval will be obtained by local researchers, and participants will provide informed consent before the study commences. Participants will typically receive feedback and advice on their laboratory results, and referral to a local health system where appropriate.