CKDu is often described as a silent health threat, and the description is apt. Unlike the chronic kidney disease familiar to nephrologists in high-income settings, CKDu progresses without the classic metabolic hallmarks such as obesity and diabetes. It is typically not diagnosed until it reaches an advanced stage, at which point it is often fatal. The disease has been documented primarily among young adult males engaged in heat-intensive manual labor in equatorial agricultural communities, with major hotspots in Central America and South Asia and additional clusters reported in rural agricultural regions from Africa to Thailand and even in Texas. Because the condition does not fit the standard metabolic profile of kidney disease, and because it clusters geographically in ways that defy a single explanation, its underlying causes remain poorly understood despite years of investigation. What has become increasingly clear is that the burden falls on working-age populations, robbing communities of people in the prime of life.

The new research emerged from a collaboration between Boston University School of Public Health and Nicaragua-based colleagues, who together analyzed survey and biospecimen data collected in 2023 from adolescents and young adults living in five regions of Nicaragua. The study area carries a high burden of CKDu, which in Nicaragua is also referred to as Mesoamerican Nephropathy. The researchers measured participants’ estimated glomerular filtration rate, the standard clinical indicator of how well the kidneys filter waste from the blood, and used it to distinguish between two distinct risk profiles. One profile reflected the non-metabolic characteristics associated with CKDu risk. The other reflected metabolic kidney disease risk, assessed through participants’ history of high body mass index, diabetes, and hypertension. The team also gathered data on employment, sociodemographic characteristics, and environmental exposures, allowing them to test which factors tracked with declining kidney function.

The results upended two assumptions at once. First, the prevalence of poor kidney health among young girls and women was greater than previously known. This population has often been excluded from CKDu research altogether, precisely because they are rarely diagnosed with the disease; screening programs have concentrated on men working in sugarcane production, so women and girls simply never entered the data. Second, the elevated risk observed among these young females was strongly associated with high body mass index levels, pointing toward metabolic kidney disease rather than the heat-driven, non-metabolic form that defines CKDu. In other words, the study appears to have captured early signals of a parallel epidemic of metabolic kidney dysfunction developing alongside the recognized occupational one, in a population that existing surveillance systems were never designed to detect.

The occupational story did not disappear entirely. The researchers did identify poor kidney health among heat-exposed young males working in sugarcane fields, consistent with the established understanding of CKDu as a disease linked to extreme occupational heat. Yet the majority of participants who exhibited higher poor kidney health did not work in heat-intensive environments at all. That single observation reframes the entire epidemiology of the region. Extreme heat, while clearly important, is not the sole driver of poor kidney health among young people there. Instead, the data suggest multiple pathways to kidney disease operating simultaneously, some occupational and some not, converging on a generation that is losing kidney function at younger ages than comparable populations in the United States, against whom the Nicaraguan participants were benchmarked.

Just as revealing were the factors that did not show up. The researchers did not observe significant links between poor kidney health and drinking water, low socioeconomic status, or non-sugarcane heat-intensive work. These null findings matter because several of them correspond to leading hypotheses in the CKDu literature. Contaminated or insufficient drinking water, poverty, and heat exposure in forms of manual labor other than sugarcane harvesting have all been proposed as contributors to the disease. The absence of significant associations in this dataset does not settle those debates, but it narrows the field and strengthens the case made by the study’s senior and corresponding author, Jessica Leibler, associate professor of environmental health at Boston University School of Public Health, that non-occupational factors such as genetic susceptibilities or environmental exposures may be shaping kidney health in the region from an early age.

For the research team, the surprise was intellectual but the implication is practical. “We were surprised to see that there appears to be multiple pathways to kidney disease in this region among young people and that exposure to extreme heat, while important, is not the sole driver of poor kidney health here,” Leibler says. “We were also interested to see how prevalent poor kidney health was among girls and young women. We believe we identified early and important signals of kidney disease risk that may allow for early interventions in this region.” Early intervention is the operative phrase. If kidney dysfunction is detectable in adolescents and young adults through estimated glomerular filtration rate measurements and metabolic indicators, then screening programs that currently begin, in effect, with adult male sugarcane workers are arriving decades and one entire demographic group too late.

Co-lead author Selene Vences Brown, a PhD student in environmental health at Boston University School of Public Health, draws the surveillance conclusion explicitly. “Our findings suggest that there may be non-occupational factors affecting kidney health in this region, such as genetic susceptibilities or environmental exposures, and that young people, including girls and women, should be involved in surveillance efforts,” she says. “To date, kidney disease screening is focused on men working in sugarcane production.” The consequences of that narrow focus extend well beyond clinic walls. Co-lead author Yirong Yuan, a PhD student in biostatistics at the school, emphasizes the social dimension: CKDu inflicts social and economic consequences, leading to financial instability for families and contributing to intergenerational poverty. A disease that strikes working-age adults in agricultural communities removes household earners, drains family savings, and passes economic disadvantage to the next generation, making early detection not only a medical priority but an economic one.

The team is not stopping at a cross-sectional snapshot. The researchers are continuing to study early-life, metabolic, and occupational risk factors among young people in Nicaragua, and Yuan is currently analyzing longitudinal kidney health data to identify patterns and trajectories in kidney function among these populations. Longitudinal analysis is the critical next step, because distinguishing a temporary dip in filtration rate from the beginning of a progressive, irreversible decline requires watching the same individuals over time. The work also stands as a model of research practice. Leibler describes it as a testament to cross-collaboration across research disciplines, with doctoral students in environmental health and biostatistics co-leading the manuscript, and says she would like to see that collaborative approach become more commonplace in doctoral studies because it reflects a sharing of expertise vital for impactful public health research. Vences Brown adds a note about the human foundation of the project: “We are very grateful to our Nicaragua-based colleagues, whose dedication and commitment to this research were critical to the project’s success.”

Taken together, the study delivers a message that reaches far beyond the sugarcane fields of Nicaragua. CKDu is a global problem, occurring across Central America and South Asia with additional hotspots in rural agricultural communities from Africa to Thailand and within the United States itself, and the Nicaraguan findings suggest that wherever it takes hold, the populations at risk may be broader and younger than screening programs assume. Adolescents and young women, historically invisible in CKDu research because they are rarely diagnosed, now appear in the data with measurable kidney dysfunction, some of it tied to metabolic risk factors such as elevated body mass index rather than to heat exposure at all. If the silent epidemic of kidney disease in hot agricultural regions is to be caught before it becomes fatal, the surveillance net will need to widen to include the young, the female, and the non-agricultural, and it will need to begin well before workers ever set foot in a cane field.

Subject of Research: Chronic kidney disease of unknown origin and metabolic kidney disease risk among adolescents and young adults in Nicaragua

Article Title: Kidney disease in Nicaragua linked to adolescents and young women, and those without occupational heat exposure

Article References: Kidney disease in Nicaragua linked to adolescents and young women, and those without occupational heat exposure. (n.d.). Original publication

Image Credits: AI Generated

DOI: Not provided

Keywords: CKDu, chronic kidney disease, Nicaragua, Mesoamerican Nephropathy, kidney health, adolescents, young women, body mass index, occupational heat exposure, metabolic kidney disease, public health surveillance, Boston University