SPECTRUM OF DIURNAL RHYTHMS IN GLOMERULAR-PERMEABILITY IN PATIENTS WITH MEMBRANOUS NEPHROPATHY

Background. Diurnal rhythms in proteinuria and selectivity index (SI) of proteinuria can vary from patient to patient with respect to phase and amplitude (A/M) and in some cases rhythms are absent. The aim of t he present study was to relate this variability to a different pattern of diurnal rhythms in permselectivity of the glomerular capillary wal l (GCW). Methods. Ten patients with nephrotic syndrome due to membrano us nephropathy were studied. Diurnal rhythmicity in size-dependent per mselectivity of the GCW was determined by measuring 3-h fractional cle arances of dextrans (30-90 Angstrom) over a period of 1 day. Results. Four types of rhythmicity could be recognized. Type I and II only diff ered in the magnitude of the diurnal variability in glomerular transpo rt through large pores (r(2)) and shunt pathway (omega). Both had norm al rhythms in clearance of proteins and SI, but all rhythms were more pronounced in the patients with normal renal function and mild histolo gical abnormalities (type II). Although type III also had a normal GFR and minor histological lesions, only transport through omega (and not through r(2)) showed a significant diurnal rhythm, which implied that this type did not have a normal rhythm in SI. The patients with advan ced renal failure and extensive interstitial lesions neither had a rhy thm in permselectivity nor had normal rhythms for proteinuria and SI ( type IV). Conclusions. The type of rhythmicity in glomerular permeabil ity corresponds well with the presence and phase of rhythms in clearan ce of proteins and in SI of the proteinuria.