Winterborn MH, Bradwell AR, Chesner IM, Jones GT  The origin of proteinuria at high altitude  Postgraduate Medical Journal 1987; 63: 179-181

Urinary protein excretion was measured before and after the intravenous infusion of lysine in 14 normal subjects after 4-6 days acclimatization at 4846m.  Urinary albumin excretion before lysine was elevated in 11 subjects but alpha₁-microglobulin was detected in only four.  After lysine a large increase in albumin excretion occurred in all subjects. Together with the absence of alpha₁-microglobulin before lysine this implies that increased glomerular capillary permeability is the major cause of proteinuria after acclimatization to high altitude.  The estimated minimum glomerular fluid albumin concentration was increased two to three fold above the published values in normal controls.