Table 1.

CKDu studies that include measurements of kidney injury biomarkers

Study	Country	Total Na No. controls % women	Biomarker(s)	Normalized to urinary creatinine?	Assay / instrument	Other measures of kidney function	Specimen collection procedures
Adult populations
Gunawickrama et al. Diseases, 202271	Sri Lanka	56 total	Plasma IL-1α	N/A	ThermoFisher Scientific assays (ELISA): BMS243-2 (IL-1 α), KAC1261 (IL-6), BMS228 (IFNγ), BMS2034 (TNFα), BMS281 (MCP-1)	SCr, eGFR (CKD-EPICr 2009 and MDRD)	No details on the timing of sample collection
		No controls	Plasma IL-6
		No participant demographics	Plasma MCP-1
			Plasma TNFα
			Plasma INFγ
Swa et al. Kidney Dialysis, 202265	Sri Lanka	134 total	Serum RBP-4	N/A	Luminex xMAP biomarker assay, select samples confirmed with Abcam ELISA (RBP-4)	SCr, eGFR (CKD-EPICr 2009)	No details on the timing of sample collection
		90 controls
		39.6% women
Abdul et al. Int J Environ Res Public Health, 202131	Sri Lanka	210 total	Urinary KIM-1	Yes	Cusabio ELISA (KIM-1 and B2M), Ray Biotech ELIZA (NGAL)	SCr, eGFR (CKD-EPICr 2009)	First morning void (6–8 am)
		No controls	Urinary NGAL
		40.9% women	Urinary B2M
De Silva et al. PLOS Negl Trop Dis, 201629	Sri Lanka	223 total	Urinary KIM-1	Yes	Cusabio ELISA (KIM-1), Ray Biotech ELISA (NGAL)	SCr, eGFR (CKD-EPICr 2009)	First morning void
		106 controls	Urinary NGAL
		Excluded women
Ekanayake et al. Int J Environ Res Public Health, 202232	Sri Lanka	228 total	Urinary KIM-1	Yes	Cusabio ELISA (both KIM-1 and NGAL)	SCr, eGFR (CKD-EPICr 2021)	First morning void
		168 controls	Urinary NGAL
		40.7% women
Fernando et al. KIR, 201930	Sri Lanka	406 total	Urinary KIM-1	Only in some analyses	Luminex xMAP custom biomarker bead assay kits (CERTKD-05 and HKI6/MAG-99-K-02) from Merck Millipore; using Luminex MAGPIX analyzer.	SCr, eGFR (unspecified equation)	Random spot urine
		164 controls)	Urinary NGAL
		40% women	Urinary Cystatin c
			Urinary B2M
			Urinary OPN
			Urinary A1M
			Urinary TIMP-1
			Urinary RBP4
Nanayakkara et al. Environ Health Prev Med, 201263	Sri Lanka	237 total	Urinary A1M	Yes	Latex agglutination immunoassay (A1M), calorimetric assay (NAG).	SCr, eGFR (MDRD)	Random spot urine
		131 controls	Urinary NAG
		54.5% women
Wijkstrom et al. PLOS One, 201894	Sri Lanka	11 total	Urinary A1M	Only for A1M	R&D ELISA (KIM-1). Others not specified.	SCr, eGFR (CKD-EPICr 2009)	Random spot urine at time of kidney biopsy (or 5–6 mo later if missing)
		No controls	Urinary NGAL
		No women	Urinary KIM-1
Wanigasuriya et al. Ceylon Med J, 201748	Sri Lanka	116 total	Urinary KIM-1	Yes	Millipore multiplexed Luminex kit (all biomarkers).		Random spot urine; time of collection not indicated
		79 controls	Urinary Clusterin
		14.5% women	Urinary B2M
			Urinary Fibrinogen
Kulasooriya et al. Int J Envi Res Public Health, 202135	Sri Lanka	218 total	Urinary NGAL	No	Particle-enhanced turbidimetric immunoassay method (Roche cobas C 501)	SCr	Preshift first morning void (5–8 am), postshift spot urine (4–6 pm), evening spot urine (7–10 pm)
		67 controls
		40.3% women
Siriwardhana et al. BMC Nephrol, 201460	Sri Lanka	60 total	Urinary B2M	No	Bioquant B-2MG BQO10T (B2M)		Random spot urine
		30 controls
		33.3% women
Herath et al. Journal of Water and Health, 201873	Sri Lanka	84 total	Urinary L-FABP	Yes	Not described		No details on timing of sample collection.
		No controls
		No participant demographics
Hansson et al. Occup Environ Med, 202247	Nicaragua	68 total	Urinary KIM-1	Yes	Bio-Plex Pro RBM Kidney Toxicity Panel 1 (includes all studied biomarkers in a single assay)	SCr, eGFR (CKD-EPICr)	Random spot urine; early morning hour preshift; before and after harvest season
		46 controls	Urinary MCP-1
		Excluded women	Urinary Calbindin
			Urinary GST-π
			Urinary Clusterin
			Urinary IL-18
Wesseling et al. Envi Res, 201634	Nicaragua	54 total	Urinary KIM-1	Yes	Bioporto ELISA (NGAL), BioAssay Works ELISA (KIM-1), Western Blot using ENZO LIfe Science monoclonoal antibodies (Hsp72)	eGFR (CKD-EPICr 2009)	Random spot urine; preshift (3–5 am) or postshift (4–7 pm) at workplace; before and after harvest season
		25 controls	Urinary NGAL
		Excluded women	Urinary Hsp72
Laws et al. AJKD, 201633	Nicaragua	284 total	Urinary NGAL	Yes	Bioporto ELISA (NGAL), MBL ELISA (IL-18), colorimetric assay by Roche (NAG)	eGFR (CKD-EPICr 2009)	Random spot urine; before and after harvest season.
		No controls	Urinary IL-18
		22% women	Urinary NAG
Petropoulos et al. Kidney360, 202041	Nicaragua	251 total	Urinary NAG	Adjusted for urine Cr in regression models	Bioporto ELISA (NGAL and IL-18), Roche colorimetric assay (NAG)	SCr, eGFR (CKD-EPICr 2009)	Preharvest random spot urine
		No controls	Urinary NGAL
		22% women	Urinary IL-18
Gonzalez-Quiroz et al. J Am Soc Nephrol, 201828	Nicaragua	104 total	Urinary NGAL	Yes	ELH-Lipocalin2 RayBiotech (NGAL)	SCr, eGFR (CKD-EPICr 2009)	Random spot urine
		No controls
		Excluded women
Gonzalez-Quiroz et al. BMC Nephrol, 201927	Nicaragua	105 total	Urinary NGAL	Yes	ELH-Lipocalin2 RayBiotech (NGAL)	SCr, eGFR (CKD-EPICr 2009 and CKD-EPICr-Cys 2012)	Random spot urine
		No controls
		Excluded women
Butler-Dawson et al. J Expo Sci Environ Epidemiol, 202237	Guatemala	222 total	Urinary NGAL	Yes	Quantikine ELISA by R&D Systems (NGAL)	SCr, eGFR (CKD-EPICr 2009)	Random spot urine, variable times (morning and afternoon) while workers were in the field
		No controls
		Excluded women
Diaz de Leon-Martinez et al. Envi Sci Pollut Res Int, 201936	Mexico	34 total	Urinary KIM-1	No	Magnetic Luminex Performance Assay	SCr, eGFR (CKD-EPICr)	First morning void
		No controls	Urinary NGAL
		100% women (excluded men)	Urinary Cystatin c
Pediatric Populations
De Silva et al. Children, 202125	Sri Lanka	909 total adolescents	Urinary KIM-1	Yes	Cusabio Technology ELISA (both KIM-1 and NGAL)		First morning void (6–8 am)
		No controls	Urinary NGAL
		53.2% female
Gunasekara et al. Sci Rep, 202295	Sri Lanka	804 total adolescents	Urinary KIM-1	Yes	Cusabio Technology ELISA (KIM-1 and NGAL)		First morning void
		164 controls	Urinary NGAL
		53.2% female
Gunasekara et al. Ped Neph39	Sri Lanka	922 total adolescents	Urinary KIM-1	Yes	Cusabio Technology ELISA (KIM-1 and NGAL)		Early morning void
		677 controls	Urinary NGAL
		54.7% female
Sandamini et al. World J Ped, 202267	Sri Lanka	892 total adolescents	Urinary Cystatin c	Yes	Cusabio CSB-E08384h (Cystatin c)	UACR	First morning void
		471 controls
		52.9% female
Ramirez-Rubio et al. NDT, 201642	Nicaragua	200 total adolescents	Urinary NGAL	Yes	Bioporto ELISA (NGAL), MBL ELISA (IL-18), Roche colorimetric assay (NAG)		Random spot urine.
		No controls	Urinary NAG
		50% female	Urinary IL-18
Leibler et al. Ped Neph26	Nicaragua	210 total adolescents	Urinary KIM-1	Yes	MesoScale Discovery Platform (all biomarkers)		Random spot urine.
		No controls	Urinary NGAL
		49.5% female	Urinary IL-18
			Urinary MCP-1
			Urinary YKL-40
Cardenas-Gonzalez et al. Environ Res38	Mexico	83 total children (5-12y)	Urinary KIM-1	Adjusted for urine Cr in selected regression models	Microbead-based assay developed by collaborators (KIM-1 and NGAL)	SCrUACR	Random spot urine
		No controls	Urinary NGAL
		43.4% female

A1M, alpha-1-microglobulin; B2M, beta-2-microglobulin; CKD-EPI, Chronic Kidney Disease Epidemiology Collaboration; CKDu, CKD of unknown etiology; ELISA, enzyme linked immunosorbent assay; GST-π, glutathione-S-transferase pi; INFy, interferon gamma; IL-1a, interleukin 1 alpha; IL-6, interleukin 6; IL-18, interleukin 18; KIM-1, kidney injury molecule 1; L-FABP, liver-fatty acid binding protein; MCP-1, monocyte chemoattractant factor 1; NAG, N-acetyl-beta-D-glucosaminidase; NGAL, neutrophil gelatinase-associated lipocalin; No., number of; RBP-4, retinol binding protein 4; SCr, serum creatinine; TIMP1, tissue inhibitor matrix metalloproteinase 1; TNFa, tumor necrosis factor alpha; UACR, urinary albumin-to-creatinine ratio.

^aTotal N represents the number of participants in which kidney injury biomarkers were measured. Some studies may have included additional participants in the design and measured kidney injury biomarkers in a subsample.