Athletic pseudonephritis in male cross-country ultra-marathoners: a comparative observational study.

BACKGROUND/OBJECTIVE: Athletes have commonly reported hematuria, cylindruria, and proteinuria, which are consistent with "athletic pseudonephritis." To date, little is known about the overall consequences of 100 km (62.5-mile) cross-country ultra-marathons on Asian male runners. This study aimed to examine (i) acute urinary changes in runners with athletic pseudonephritis following a 100 km cross-country ultra-marathon and (ii) whether this phenomenon is associated with the runners average running speed. METHODS: Twenty male Taiwanese ultra-marathoners were prospectively recruited. Urinary parameters were analyzed before and immediately after the 2020 Taiwania 100 K Ultra Trail. Competitors ran on a rugged forest path and the official cut-off time was 15 h. RESULTS: Participants showed a statistically significant post-race increase (p < 0.001) in urinary red blood cell counts. No significant difference was noted in urinary cast in the immediate post-race values compared to the pre-race values (p = 0.488). Urinary chemistry showed statistically significant increases in specific gravity (p < 0.001), osmolality (p < 0.001), creatinine (p = 0.027), microalbumin (p < 0.001), protein (p < 0.001), and myoglobin (p < 0.001) between the pre- and post-race values. Additionally, 10 (50%) post-race specimens had albumin-to-creatinine ratios >30 mg/g, and 9 (45%) specimens showed protein-to-creatinine ratios >0.2 mg/mg. The association between running speed and red blood cells in urine showed a p-value of 0.368. There were no correlations between running speed and changes in albumin-to-creatinine ratio (rs = -0.105, p = 0.661), protein-to-creatinine ratio (rs = -0.013, p = 0.957), or myoglobin (rs = 0.003, p = 0.99) levels. CONCLUSION: Exercise-related hematuria and proteinuria were frequently observed in the Asian male cross-country ultra-marathoners. A faster running speed was not associated with the degree of exercise-induced hematuria, proteinuria or myoglobinuria.