Brain natriuretic peptide (BNP) is a polypeptide hormone which is homologous with atrial natriuretic peptide (ANP). Since the 2 hormones partially share common secretory regulation we simultaneously assessed plasma BNP and ANP in patients with chronic glomerulonephritis without apparent cardiac involvement. Blood samples were taken from patients with serum creatinine (Cr) 0.5-1.2 mg/dl (normal renal function), patients with Cr > 1.2 mg/dl (chronic renal failure) and dialysis patients. BNP did not correlate with serum Cr, which indicated our antibody did not recognize accumulated metabolites due to decreased renal function. BNP and ANP decreased after dialysis-(p < 0.01). Changes of BNP during HD correlated with changes in body weight (p < 0.05). Plasma BNP concentrations were 12.0 +/- 22.0 pg/ml in patients with normal renal function, 17.6 +/- 23.4 pg/ml in chronic renal failure, and 91.5 +/- 93.5 in dialysis patients (p < 0.05 compared with patients with normal renal function). Plasma BNP/ANP ratios were 0.507 +/- 0.646 in patients with normal renal function, 0.392 +/- 0.842 in chronic renal failure, and 0.573 +/- 0.431 in dialysis patients (p < 0.05, compared with chronic renal failure). Increased ANP in chronic renal failure and dialysis indicates volume overload on atrium. In contrast, BNP increased only in dialysis patients, which indicates differences of hemodynamic stress in chronic renal failure and dialysis. We conclude that simultaneous measurements of plasma BNP and ANP further discriminate salt-water and hemodynamic abnormalities in dialysis patients.