Modification of mild proteinuria by postural and other mechanisms affecting haemodynamics.

Changes in urinary protein excretion induced by standing or by the application of venous tourniquets to the thighs while the patient is in the supine position were studied in patients with mild proteinuria and compared with the changes that occur in severe proteinuria (greater than 1 mg/min). Protein excretion decreased in the majority of patients. Irrespective of the initial degree of proteinuria. The increased rate of protein excretion that occurred in a minority of patients when standing may represent a phenomenon analogous to orthostatic proteinuria.