Abstract
Objective
To evaluate the incidence of acute kidney injury (AKI) during the Leadville 100 ultramarathon held at high altitude (2800–3840 m) and the utility of urine dipstick at detecting AKI.
Methods
This was a prospective observational study. Blood and urine samples were collected from voluntary athletes before and immediately after the Leadville 100-mile race in August 2014.
Results
Postrace dipstick urinalysis was done on 70 runners (51 finishers), and a postrace blood sample was obtained from 84 runners (61 finishers). Both prerace and postrace samples were collected from 37 participants, which were included in the analysis. AKI was defined as a serum creatinine increase (≥1.5 times or ≥0.3 mg/dL from baseline) according to Kidney Disease: Improving Global Outcomes (KDIGO) Group. Eighteen runners (48.6%) met the criteria for stage 1 AKI. Using a binary logistic regression, the only factors statistically correlated with likelihood of AKI were runners who lost more weight at the finish line and male gender (P < .05 and P = .05, respectively). Age, race time, race completion status, use of NSAIDs (nonsteroidal anti-inflammatory drugs) before or during the race, BMI (body mass index), and postrace creatine kinase and sodium levels were not correlated with presence of AKI. Using urine appearance (color ≥4 out of 8 or not-clear) or specific gravity (≥1.025) criteria predicted those meeting the stage 1 AKI criteria with sensitivity of 81.3% and specificity of 37.5%. Using urine protein of at least 1+ predicted those meeting the stage 1 AKI criteria with sensitivity of 43.8% and specificity of 87.5%.
Conclusions
Incidence of stage 1 AKI was relatively high in this ultramarathon. There was a higher rate of AKI among those who lost more weight at the finish line and male runners. Urine dipstick may be a useful screening tool for AKI.We thank the Leadville Race Series. Funded in part by the ACSM Clinical Sports Medicine Endowment Grant.