Urinary Kidney Injury Molecule-1 but Not Urinary Neutrophil Gelatinase Associated Lipocalin Is Increased After Short Maximal Exercise

Background And Aims: Urinary neutrophil gelatinase associated lipocalin (uNGAL) and urinary kidney injury molecule-1 (uKIM-1) are markers of acute kidney injury. The albuminuria is a well-known abnormality after physical exercise. The aim of this study was to investigate changes in uNGAL and uKIM-1 after intensive exercise causing albuminuria.

Methods: The study population consisted of 19 participants (10 males and 9 females). The mean age of participants was 35.74 years. All were fit amateur runners; the mean body mass index was 21.99 in females and 24.71 in males. The subjects underwent a graded treadmill exercise test (GXT) according to the Bruce protocol. Maximal oxygen consumption (VO2max) was measured. Immediately before and after the test urine was collected. Urinary creatinine, albumin, NGAL, and KIM-1 were measured. Albumin to creatinine (ACR), KIM-1 to creatinine (KCR), and NGAL to creatinine (NCR) ratios were calculated.

Results: The mean VO2max was 53.68 in females and 59.54 mL/min/kg in males. Albuminuria and ACR were significantly higher after exercise. An increase in the ACR from 8.82 to 114.35 mg/g (p < 0.01) was observed. uKIM-1 increased significantly after exercise from 849.02 to 1,243.26 pg/mL (p < 0.05). KCR increased from 1,239.1 to 1,725.9 ng/g but without statistical significance (p = 0.07). There were no statistical changes in pre- and post-run uNGAL levels. There was no correlation between post-GXT albuminuria and uKIM-1.

Conclusions: uKIM-1 is a very sensitive marker of kidney dysfunction. In our study, uKIM-1 increased significantly after a very short period of exercise. It is not clear if the increase in KIM-1 is caused by post-exercise albuminuria.