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 | ||||||||||||
| Unit | LOQ | % below LOQ | Unit/mmol creatinine | n* | Baseline | End-harvest | Cross-harvest trend | n* | Baseline | End-harvest | Cross-harvest trend | Baseline | X-harvest differential trend | |
| Median (IQR) | p† | Median (IQR) | p† | p† | p† | |||||||||
| U-Clusterin | ng/mL | 0.91 | 65 | ng | 22 | 0.19 (0.13–0.81) | 0.38 (0.18–1.18) | 0.23 | 46 | 0.12 (0.06–0.41) | 0.25 (0.12–0.43) | 0.10 | 0.23 | 0.96 |
| U-Calbindin | ng/mL | 1.6 | 45 | ng | 22 | 2.4 (0.3–6.4) | 9.6 (0.5–38) | 0.001 | 46 | 1.0 (0.2–5.1) | 0.8 (0.4–4.4) | 0.50 | 0.31 | 0.02 |
| U-MCP-1 | ng/mL | 0.01 | 45 | pg | 22 | 5 (2–11) | 43 (6–127) | <0.001 | 46 | 4 (1–11) | 4 (2–11) | 0.34 | 0.42 | <0.001 |
| U-KIM-1 | ng/mL | 0.01 | 35 | pg | 22 | 7 (2–31) | 59 (6–163) | <0.001 | 46 | 6 (2–20) | 5 (3–20) | 0.23 | 0.23 | 0.002 |
| U-GST-π | ng/mL | 0.06 | 38 | ng | 22 | 0.05 (0.01–0.13) | 0.17 (0.02–0.78) | 0.01 | 46 | 0.04 (0.01–0.18) | 0.03 (0.02–0.13) | 0.98 | 0.91 | 0.04 |
| S-K | mmol/L | NA | NA | NA | 30 | 4.1 (3.8–4.4) | 4.1 (3.5–4.5) | 0.19 | 53 | 4.1 (3.8–4.4) | 4.1 (3.9–4.3) | 0.94 | 0.52 | 0.28 |
| FEK | % | NA | NA | NA | 22 | 10 (8–13) | 20 (15–25) | <0.001 | 49‡ | 10 (9–13) | 11 (9–16) | 0.29 | 0.55 | <0.001 |
| U-Albumin | mg/L | 3 | 66 | g | 22 | 0.43 (0.21–0.54) | 1.42 (0.76–3.20) | <0.001 | 49‡ | 0.37 (0.27–0.61) | 0.62 (0.41–1.14) | 0.09 | 0.54 | 0.001 |
| B-Hb | g/dL | NA | NA | NA | 28§ | 13.6 (13.2–14.3) | 12.2 (11.8–13.3) | <0.001 | 52§ | 14.4 (13.6–15.0) | 14.1 (13.3–14.7) | 0.23 | 0.05 | <0.001 |
| S-EPO | mIU/mL | 0.4 | 13 | NA | 15 | 5.4 (2.3–6.1) | 1.9 (0.7–3.3) | <0.001 | 21 | 4.9 (3.5–5.6) | 6.0 (4.1–8.0) | 0.04 | 0.52 | <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.