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 (125mg 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.