Effects of dietary protein restriction on fibrinogen and albumin metabolism in nephrotic patients

Background. Nephrotic syndrome (NS) is characterized by profound changes in albumin and fibrinogen levels. Dietary protein restriction has been advoca ted in the treatment of patients with NS, but its effects on albumin and fi brinogen metabolism have not been fully elucidated. Methods. We evaluated the effects of dietary protein restriction on endogen ous leucine flux (ELF), fibrinogen and albumin metabolism in seven patients with NS who consumed either a normal protein diet (NPD; 1.20 +/- 0.06 g/kg /day), or a low protein diet (LPS,0.66 +/- 0.04 g/kg/day) for four weeks. S even normal subjects served as controls. The postabsorptive ELF value, frac tional synthesis rate (FSR) and absolute synthesis rate (ASR) of both album in and fibrinogen were evaluated during the last 120 minutes of a five-hour 5,5,5-D3-L-leucine infusion. Results. During the NPD regimen. ELF was increased, serum albumin was reduc ed, plasma fibrinogen was increased, albumin FSR and ASR were both increase d, fibrinogen FSR was normal, and fibrinogen ASR was greater in patients wi th NS compared to controls. In patients with NS the LPD regimen reduced pro teinuria. ELF, albumin FSR and ASR, plasma fibrinogen levels, fibrinogen AS R, and increased serum ulbumin levels. Dietary-induced changes in albumin a nd fibrinogen synthesis were significantly correlated (r = 0.719, P < 0.05) . Conclusions. Patients with NS treated with LPD show: (1) a reduction of pro teinuria, albumin ASR and FSR, with an increase in serum albumin levels and its intravascular pool; (2) a decrease of fibrinogen ASR, with a reduction in both plasma fibrinogen levels and intravascular pool: and (3) a reduced rate of whole body proteolysis.