CHANGES IN BRAIN NATRIURETIC PEPTIDE AND ATRIAL-NATRIURETIC-PEPTIDE PLASMA-CONCENTRATIONS DURING HEMODIALYSIS IN PATIENTS WITH CHRONIC-RENAL-FAILURE

The present study aimed to investigate whether brain natriuretic peptide (BNP), atrial natriuretic peptide (ANP), cortisol and thyroid hormone concentrations change during hemodialysis in patients with chronic renal failure. Blood samples were withdrawn in 30 patients with chronic renal failure before hemodialysis, 2 hours after the beginning and at the end of hemodialysis. ANP and BNP concentrations were determined by radioimmunoassay after Sep Pak C-18 extraction. Cortisol, T-3, T-4, FT4 and TSH serum concentrations were measured by enzyme immunoassay. BNP and ANP plasma levels were strongly elevated in patients with renal failure (BNP 22.4 fold ANP 4.7 fold versus controls [n=20]) and decreased significantly (p<0.001) during hemodialysis (BNP [pg/ml]: 192.1+/-24.9, 178.6+/-23.0, 167.2+/-21.8; ANP [pg/ml]: 240.2+/-28.7, 166.7+/-21.3, 133.0+/-15.5). BNP plasma concentrations showed a stronger elevation than ANP plasma levels and a less pronounced decrease during hemodialysis (BNP: 13.5+/-1.8%, ANP: 40.2+/-3.5%, p<0.001) which might in part be due to the longer half-life of BNP. Cortisol and TSH levels did not change significantly whereas T-3, T-4 and FT4 levels increased significantly (p<0.001) during hemodialysis. Since corticosteroids and thyroid hormones stimulate natriuretic peptide release, these data suggest that the dialysis-induced decrease of ANP and BNP plasma concentrations is not augmented by a loss of cortisol or thyroid hormones during hemodialysis. The present data provide support that BNP and ANP plasma concentrations are sensitive indicators of the extracellular fluid volume status. The stronger elevation of BNP concentrations and the less pronounced decrease during hemodialysis suggest that BNP and ANP might be regulated differently.