Plasma protein synthesis in patients with low-grade nephrotic proteinuria.
Overt nephrotic syndrome is characterized by albumin and fibrinogen hyperproduction and reduced very low density lipoprotein apolipoprotein B-100 (VLDL apoB-100) clearance. Whether similar changes also occur in low-grade proteinuria is not known. Thus we measured albumin, fibrinogen, and VLDL apoB-100 kinetics in six patients with modest proteinuria and normal creatinine clearance (P) and in ten control subjects (C) by leucine tracer infusion and precursor-product relationships. In P, plasma albumin concentration was decreased (P < 0.003), whereas concentrations of fibrinogen and VLDL apoB-100 were increased (P < 0.001). In P, albumin fractional secretion rate (FSR) was increased (P < 0.01), fibrinogen FSR was normal, and VLDL apoB-100 FSR was decreased (P < 0.03). As a result, in P, absolute secretion rates (ASR) of albumin and fibrinogen were increased (P < 0.03), whereas VLDL apoB-100 ASR was normal. Albumin FSR was inversely correlated to oncotic pressure in P but not in C. These findings suggest that low-grade nephrotic proteinuria is characterized by simultaneous multiple alterations in turnover rates of albumin, fibrinogen, and VLDL apoB-100. Their pathogenesis, however, appears to be multifactorial.
Zanetti
M
M
Departments of Metabolic Diseases and Internal Medicine, University of Padova, 35128 Padua, Italy.
Barazzoni
R
R
Garibotto
G
G
Davanzo
G
G
Gabelli
C
C
Kiwanuka
E
E
Piccoli
A
A
Tosolini
M
M
Tessari
P
P
D000328:Adult; D053299:Apolipoprotein B-100; D001055:Apolipoproteins B / Q000097:blood; D001798:Blood Proteins / Q000096:biosynthesis*; D005260:Female; D005340:Fibrinogen / Q000032:analysis; D006801:Humans; D007700:Kinetics; D008079:Lipoproteins, VLDL / Q000097:blood; D008297:Male; D008875:Middle Aged; D009404:Nephrotic Syndrome / Q000652:urine*; D011507:Proteinuria / Q000097:blood* / Q000209:etiology*; D012709:Serum Albumin / Q000032:analysis
D053299:Apolipoprotein B-100; D001055:Apolipoproteins B; D001798:Blood Proteins; D008079:Lipoproteins, VLDL; D012709:Serum Albumin; D005340:Fibrinogen