High plasma levels of atrial natriuretic peptide in preascitic cirrhosis: Indirect evidence of reduced natriuretic effectiveness of the peptide

Abstract

Controversial results come from spot measurements of plasma atrial natriuretic peptide (ANP) in compensated cirrhotic patients. Moreover, either blunted or exaggerated natriuresis has been described after maneuvers increasing plasma ANP. This does not make it possible to delineate the ANP effectiveness. Plasma ANP, renin activity (PRA) and aldosterone and hematocrit were serially measured (7 AM, 9 AM, 6 PM, and 11 PM) in nine preascitic cirrhotic outpatients and in nine healthy subjects on normal sodium diet (150 mmol/day) and carrying on their usual activities (mobile from 7 AM to 10 PM). Daily natriuresis was monitored the day before and during the study. In both groups, ANP peaked at the end of the recumbence period (7 AM) and declined on the assumption of the upright position, so that both ANP values of the standing period were significantly lower than the mean daily level. These fluctuations were reciprocal to PRA and hematocrit changes. Patients showed steadily elevated plasma ANP and reduced PRA (ANP mean daily level: 33.3 ± 3.8 vs. 15.5 ± 3.2 pg/mL, P = .004; PRA: 0.76 ± 0.23 vs. 1.66 ± 0.21 ng/mL/hr, P = .003). Aldosterone fluctuations and mean daily level were similar in the two groups (mean daily level: 122 ± 11 vs. 119 ± 9 pg/mL). Natriuresis was well adapted to the sodium intake and similar in healthy subjects (day 1: 152 ± 11 mmol; day 2: 138 ± 12.5 mmol) and patients (143 ± 15 mmol; 148 ± 29 mmol). Preascitic cirrhotic patients on a normal salt intake and carrying on their usual activities develop a new steady state requiring increased ANP levels to maintain a sodium balance. In addition to a reduced renal sensitivity to ANP, several subtle abnormalities of the antinatriuretic forces may yield the renal hyporesponsiveness to the peptide.