EFFECTS OF POSTURE ON CREATININE CLEARANCE AND URINARY PROTEIN EXCRETION IN PATIENTS WITH VARIOUS RENAL DISEASES

To investigate the effects of a change in posture on renal function, w e measured Ccr and the urinary excretion of protein, albumin, immunogl obulin G (IgG) and transferrin in 80 patients with renal disease and i n 9 healthy controls. Patients and controls were studied serially whil e supine for 60 min; then after standing upright for 60 min. Almost al l subjects showed a drop in the Ccr with standing (p <0.01). The perce nt change in Ccr after standing was more remarkable in patients with g lomerulonephritis vs the healthy subjects (74.0 +/- 21.9% vs 89.9 +/- 12.3%, p <0.01). The change in urinary excretion of protein and albumi n after standing in patients with membranous nephropathy (MN-N) signif icantly exceeded that in patients with IgA nephropathy (IgA-N) (182.1 +/- 89.3% vs 108.1 +/- 59.2% in urinary protein and 181.7 +/- 98.7% vs 113.3 +/- 40.9% in urinary albumin, p <0.01). Urinary excretion of Ig G and transferrin tended to increase after standing in those two group s, but not significantly. Results indicate that posture affects urinar y protein excretion, probably via an increase of glomerulocapillary hy drostatic pressure and/or change in the permeability of the glomerular capillary walls. We recommend that comparable postures should be used when protein excretion is used as a diagnostic tool and in monitoring structural damage to glomeruli, particularly in patients with membran ous nephropathy.