Plasma concentration and urinary excretion of N-terminal proatrial natriuretic peptides in patients with kidney diseases

Plasma concentration and urinary excretion of N-terminal proatrial natriuretic peptides in patients with kidney diseases.BackgroundBiologically active N-terminal fragments such as proANP(1-30), proANP(31-67), and proANP(1-98) derive from the prohormone of α-human atrial natriuretic peptide [proANP(99-126) or α-ANP]. No systematic data are available for patients with different kidney diseases.MethodsSpecific immunoassays were developed to determine plasma and urine concentrations of these fragments in 121 patients with different degrees of kidney function and urinary protein excretion, respectively.ResultsIn patients with kidney disease and normal renal function without proteinuria, circulating proANP(1-30) and proANP(31-67) increased 2.8-fold and 6.5-fold, respectively. Urinary excretion of proANP(31-67) increased by a factor of 7.7 in these patients, whereas proANP(1-30) was not affected. Patients with impaired renal function had a dramatic increase of urinary proANP(31-67) excretion even before serum creatinine levels started to rise. The progression of renal failure caused a significant rise of circulating proANP(1-30) (4.3-fold) and proANP(31-67) (3.0-fold) compared with patients with normal renal function. Urinary excretion of proANP peptides significantly increased, particularly when the serum creatinine level was> 5.0 mg/dL [proANP(1-30) 26-fold, proANP(31-67) 8.4-fold]. Urinary excretion of proANP(1-30) increased up to 4.4-fold and urinary excretion of proANP(31-67) increased up to 2.4-fold in patients with proteinuria in excess of 3 g/24 h.ConclusionsPlasma concentrations and urinary excretion of proANP(1-30) and proANP(31-67) are affected by kidney disease and function, but not by proteinuria per se. It is proposed that the diseased kidney increases early urinary excretion of proANP fragments to participate in the regulation of renal function as well as sodium and water excretion