Table 2

Markers of kidney injury and function in workers with and without serum creatinine increase during sugarcane harvests at Ingenio San Antonio, Nicaragua, November 2017 to April 2019

Cases (cross-harvest SCr increase by 0.3 mg/dL)Controls (cross-harvest eGFRcrea change<10 mL/min/1.73 m2)Case–control comparison
UnitLOQ% below LOQUnit/mmol creatininen*BaselineEnd-harvestCross-harvest trendn*BaselineEnd-harvestCross-harvest trendBaselineX-harvest differential trend
Median (IQR) p Median (IQR) p p p
U-Clusterinng/mL0.9165ng220.19 (0.13–0.81)0.38 (0.18–1.18)0.23460.12 (0.06–0.41)0.25 (0.12–0.43)0.100.230.96
U-Calbindinng/mL1.645ng222.4 (0.3–6.4)9.6 (0.5–38)0.001461.0 (0.2–5.1)0.8 (0.4–4.4)0.500.310.02
U-MCP-1ng/mL0.0145pg225 (2–11)43 (6–127)<0.001464 (1–11)4 (2–11)0.340.42<0.001
U-KIM-1ng/mL0.0135pg227 (2–31)59 (6–163)<0.001466 (2–20)5 (3–20)0.230.230.002
U-GST-πng/mL0.0638ng220.05 (0.01–0.13)0.17 (0.02–0.78)0.01460.04 (0.01–0.18)0.03 (0.02–0.13)0.980.910.04
S-Kmmol/LNANANA304.1 (3.8–4.4)4.1 (3.5–4.5)0.19534.1 (3.8–4.4)4.1 (3.9–4.3)0.940.520.28
FEK%NANANA2210 (8–13)20 (15–25)<0.00149‡10 (9–13)11 (9–16)0.290.55<0.001
U-Albuminmg/L366g220.43 (0.21–0.54)1.42 (0.76–3.20)<0.00149‡0.37 (0.27–0.61)0.62 (0.41–1.14)0.090.540.001
B-Hbg/dLNANANA28§13.6 (13.2–14.3)12.2 (11.8–13.3)<0.00152§14.4 (13.6–15.0)14.1 (13.3–14.7)0.230.05<0.001
S-EPOmIU/mL0.413NA155.4 (2.3–6.1)1.9 (0.7–3.3)<0.001214.9 (3.5–5.6)6.0 (4.1–8.0)0.040.52<0.001
  • *See the Methods section for full description of selection of workers for each analysis.

  • †From linear mixed model, see the Methods section.

  • ‡Three controls randomly excluded from injury marker analyses included in this analysis.

  • §Hb levels were missing for two cases and one control.

  • B, blood; eGFR, estimated glomerular filtration rate; EPO, erythropoietin; FEK, fractional excretion of potassium; GST-π, glutathione S-transferase-π; Hb, haemoglobin; K, potassium; KIM-1, kidney injury molecule 1; LOQ, limit of quantification; MCP-1, monocyte chemoattractant protein 1; S, serum; SCr, serum creatinine; U, urine.