Urinary biomarkers KIM-1 and NGAL may predict Chronic Kidney Disease of uncertain etiology (CKDu) among Sugarcane farmers in Sri Lanka.

Abstract

Chronic kidney disease of uncertain etiology has become a major health problem among farming communities in rural Sri Lanka. This study determined the prevalence of CKDu following WHO case definition of CKDu in two disease emerging locations of Monaragala District [Warunagama (EMW) and Rahathangama (EMR)] and two non-endemic locations Matara (CM) and Nuwara Eliya (CN) in Sri Lanka. Further, the study aimed to determine the levels of tubular injury markers Kidney Injury Molecule (KIM-1) and Neutrophil Gelatinase-associated Lipocalin (NGAL) in the same study populations to assess potential early renal injury among CKDu subjects and healthy individuals from the recruited male farmers (Warunagama: n= 46, Rahathangama: n= 31, Matara: n= 47, Nuwara Eliya: n=30). Early morning first urine samples and blood samples were collected form the subjects and Creatinine normalized urinary KIM-1 and NGAL were measured using ELISA. Albuminuria (ACR ≥ 30mg/g); serum creatinine based estimation of glomerular filtration rate (eGFR) were also assessed for kidney function. Twenty five new CKDu cases were identified (EMW: n= 14 and EMR: n=11) for the first time in Monaragala District, Sri Lanka regardless no previous CKDu has been reported. Persistent albuminuria (ACR ≥ 30mg/g Cr) was also reported in new cases. No CKDu cases were identified in non-endemic study locations in CM and CN. Urinary KIM-1 and NGAL levels were significantly higher in CKDu cases in EMW and EMR. Early tubular damage as seen by higher urinary KIM-1 and NGAL was also observed in healthy farmers despite normal ACR levels. Tubular damage predicted by urinary KIM-1 and NGAL were also significantly correlated with higher urinary ACR levels. We conclude that novel urinary biomarkers KIM-1 and NGAL may predict CKDu among sugarcane farmers and its applicability over the conventional markers warrant for further studies.