Effect of posture and physical activity on urinary protein excretion by patients with glomerular proteinuria diseases

The rate of urinary protein excretion (Uprot.V) was evaluated in 20 patients with massive proteinuria caused by various histopathological types of glomerular disease. Measurements were made during five consecutive periods: period A (overnight bed rest) and periods B, C, D and E corresponding to normal everyday upright physical activity. Mean Uprot.V was significantly lower during period A (8.2 +/- 1.3 mg/min, mean +/- SEM) than during all the periods of physical activity (11.8 +/- 1.8 mg/min). For 5/20 patients, physical activity induced a mean percent increase of 340 +/- 200% and for 11 an increase of 51 +/- 7% was observed. Only in 4 patients was the rate of urinary protein excretion unaffected or decreased on the average by -20 +/- 9% during physical activity.