PT - JOURNAL ARTICLE AU - Kelsley E Joyce AU - John Delamere AU - Susie Bradwell AU - Stephen David Myers AU - Kimberly Ashdown AU - Carla Rue AU - Samuel JE Lucas AU - Owen D Thomas AU - Amy Fountain AU - Mark Edsell AU - Fiona Myers AU - Will Malein AU - Chris Imray AU - Alex Clarke AU - Chrisopher T Lewis AU - Charles Newman AU - Brian Johnson AU - Patrick Cadigan AU - Alexander Wright AU - Arthur Bradwell TI - Hypoxia is not the primary mechanism contributing to exercise-induced proteinuria AID - 10.1136/bmjsem-2019-000662 DP - 2020 Mar 01 TA - BMJ Open Sport & Exercise Medicine PG - e000662 VI - 6 IP - 1 4099 - http://bmjopensem.bmj.com/content/6/1/e000662.short 4100 - http://bmjopensem.bmj.com/content/6/1/e000662.full SO - BMJ OPEN SP EX MED2020 Mar 01; 6 AB - Introduction Proteinuria increases at altitude and with exercise, potentially as a result of hypoxia. Using urinary alpha-1 acid glycoprotein (α1-AGP) levels as a sensitive marker of proteinuria, we examined the impact of relative hypoxia due to high altitude and blood pressure-lowering medication on post-exercise proteinuria.Methods Twenty individuals were pair-matched for sex, age and ACE genotype. They completed maximal exercise tests once at sea level and twice at altitude (5035 m). Losartan (100 mg/day; angiotensin-receptor blocker) and placebo were randomly assigned within each pair 21 days before ascent. The first altitude exercise test was completed within 24–48 hours of arrival (each pair within ~1 hour). Acetazolamide (125 mg two times per day) was administrated immediately after this test for 48 hours until the second altitude exercise test.Results With placebo, post-exercise α1-AGP levels were similar at sea level and altitude. Odds ratio (OR) for increased resting α1-AGP at altitude versus sea level was greater without losartan (2.16 times greater). At altitude, OR for reduced post-exercise α1-AGP (58% lower) was higher with losartan than placebo (2.25 times greater, p=0.059) despite similar pulse oximetry (SpO2) (p=0.95) between groups. Acetazolamide reduced post-exercise proteinuria by approximately threefold (9.3±9.7 vs 3.6±6.0 μg/min; p=0.025) although changes were not correlated (r=−0.10) with significant improvements in SpO2 (69.1%±4.5% vs 75.8%±3.8%; p=0.001).Discussion Profound systemic hypoxia imposed by altitude does not result in greater post-exercise proteinuria than sea level. Losartan and acetazolamide may attenuate post-exercise proteinuria, however further research is warranted.