ADOLESCENT KIDNEY HEALTH AND ENVIRONMENTAL EXPOSURES: CHILDHOOD KIDNEY HEALTH IN UDDANAM (ChiKU) STUDY PRELIMINARY ANALYSIS

Evaluation of pediatric kidney health in hotspots for chronic kidney disease of unknown etiology (CKDu) remains limited but is key for informing early detection and prevention strategies. The overarching aim of the ChiKU Cohort is to longitudinally assess adolescent kidney health in the CKDu hotspot of Uddanam, Andhra Pradesh. Here, we present a preliminary analysis with the objective of describing baseline estimated glomerular filtration rate (eGFR) in the ChiKU cohort and examining the relationship between baseline eGFR and participant characteristics.

The ChiKU cohort enrolled adolescents from 4 schools in Kaviti Mandal, Uddanam, obtaining consent from parents and assent from students. We included students who had lived there for at least 5 consecutive years prior to enrollment. We excluded those who had previously diagnosed diabetes, hypertension, or kidney disease. Baseline data collection included self-reported participant characteristics, anthropometric and physiological measures, and point of care (POC) capillary creatinine using the Nova Biomedical Creatinine StatSensor (all collected between July and October 2024). We then measured baseline serum creatinine by IDMS-traceable Jaffe method as a confirmatory test (collected between August and October 2025 due to technical and logistical delays). For descriptive and multivariable analysis, the outcome of eGFR was calculated using serum creatinine measurements and the Bedside Schwartz formula. 

We enrolled 325 adolescents (146 males, 179 females) with median age of 13 years (IQR 1). Forty-six percent used reverse osmosis water as their primary drinking water. The most common occupation for fathers was fishing (39%) and for mothers was taking care of the home (52%). Forty-one percent had a parent working in agriculture, and 20% helped their parents with agricultural work for a median of 2 hours per week (IQR 1). Seventeen percent of participants had an SBP of ³120 mmHg and/or a DBP ³80 mmHg, 9% had SBP ³130 mmHg and/or a DBP ³80 mmHg, and <1% had greater than trace proteinuria persisting on two first morning urine dipsticks. Mean weight-, height-, and BMI-for-age z-scores were -1.5 (SD 1.4), -1.4 (SD 1.3), and -1 (SD 1.5), respectively. Median eGFR per serum creatinine was 113 ml/min/1.73m2 (IQR 25) for girls and 97 (IQR 27) for boys (Figure 1). No participants had eGFR<30. Among girls, none had eGFR per serum creatinine 30 to <60, 9% had eGFR 60 to <90 (mildly reduced), 52% had eGFR 90-120, 23% had eGFR >120-140, and 16% had eGFR>140 (possible hyperfiltration). Among boys, 2% had eGFR per serum creatinine 30 to <60, 34% had eGFR 60 to <90, 47% had eGFR 90-120, 12% had eGFR >120-140, 5% had eGFR>140. On average, eGFR yielded by the point-of-care meter was 24 points lower than that yielded by serum creatinine, which is more accurate and widely accepted. In joint effects mixed linear regression of participants with eGFR up to 140, each one-year increase in age was associated with a 6-point decrease in eGFR (95% CI -9, -3), and males on average had an eGFR 10 points lower than females (95% CI -14, -5) (Table 1).

Prevalence of mildly to moderately reduced baseline eGFR was high and prevalence of persistent proteinuria was low, suggesting a phenotype similar to CKDu that may begin in childhood. This finding should be validated longitudinally to confirm chronicity and with focus on sex-specific environmental interactions.