Hypohydration Augments the Acute Increase in Urinary Biomarkers of Kidney Injury Following the 100-mile Western States Endurance Run.

Abstract

Purpose: Ultra-endurance races may transiently increase acute kidney injury (AKI) risk, yet data on contributing factors are sparse. Therefore, we examined the acute effects of the Western States Endurance Run (WSER; [100 miles; 161 kilometers]) on urinary AKI biomarkers and kidney blood flow, while also assessing the influence of race pace and hydration status. Methods: Blood and urine samples were collected to assess urine specific gravity (USG), creatinine, and AKI risk (nephrin, neutrophil gelatinase-associated lipocalin [NGAL], insulin like growth factor binding protein 7 [IGFBP7], tissue inhibitor of metalloproteinase 2 [TIMP2], and IGFBP-7●TIMP-2). Renal blood velocity and conductance were measured via Doppler ultrasonography. Results: Pre and post measures were obtained from 36 runners (29Males/7Females, age: 44±9 years, mean finish time: 25:45:55). Urinary AKI biomarkers increased post-race, with nephrin, IGFBP7, and IGFBP7●TIMP-2 remaining elevated after indexing to creatinine (ps < 0.008). Hydration status declined, with only 8 of 35 runners remaining euhydrated post-race. Finishing euhydrated attenuated increases in urinary creatinine and creatinine-indexed IGFBP-7●TIMP-2 (ps ≤ 0.006). Faster race pace correlated with increases in USG (rho, ρ=0.338, p=0.048) and urinary creatinine (rho, ρ=0.443, p=0.010), but not with creatinine-indexed AKI biomarkers (ps ≥ 0.382). Kidney blood velocity and conductance were unchanged (ps ≥ 0.186). Conclusion: Finishing hydrated appears to help mitigate transient increase in kidney injury following an ultra-endurance race.