Asymptomatic kidney changes discovered during occupational health screening: age-dependent trends from a large cohort

Background The urinary albumin-to-creatinine ratio (uACR) and estimated glomerular filtration rate (eGFR) are key biomarkers for asymptomatic detection of chronic kidney disease (CKD), yet their combined use in preventive screening—particularly among young adults—remains uncommon. This study evaluates CKD markers in a large occupational cohort, emphasizing the early renal alterations observed in the 19–30-year age group and their distribution across older age strata. Methods Between 2021 and 2024, 12 281 healthcare workers (HCWs) aged 19–71 years participated in an occupational health surveillance program at the University Hospital of Bari, Italy. CKD was evaluated using eGFR (CKD-EPI) and uACR from spot urine samples, with classification based on the KDIGO guidelines (2024). The results were stratified by age (19–30, 31–60, and > 60 years) and comorbidities. Results Overall, 6.7% of participants met the KDIGO criteria for CKD, with 6.5% exhibiting elevated uACR (>30 mg/g) and 0.2% demonstrating reduced eGFR (<60 mL/min/1.73 m²). Young adults (19–30 years, n = 4 139): 95.3% exhibited normal renal profiles (G1–G2/A1), while 4.7% showed increased albuminuria (A2–A3) despite preserved eGFR, indicating asymptomaticsubclinical renal changes. Middle-aged adults (31–60 years, n = 5 245): 5.9% presented with mild renal impairment, characterized by elevated uACR or mild eGFR decline. Older adults (>60 years, n = 2 907): Only 84% remained in the lowest KDIGO prognostic category (G1–G2/A1), whereas 16% exhibited elevated uACR and/or reduced eGFR, consistent with age-related renal decline and a higher comorbidity burden. Among the 74 individuals with severe albuminuria (A3), 10 underwent renal biopsy, which revealed IgA nephropathy, nephroangiosclerosis, lupus nephritis, membranous GN. Conclusion Even in a predominantly healthy working population, one in 20 young adults demonstrated asymptomatic kidney alterations identifiable only through uACR screening. These findings underscore the importance of integrating both uACR and eGFR testing into occupational and preventive health programs to detect mild CKD in all age groups and promote kidney health preservation from early adulthood.