Background: Renal sodium handling in preascitic cirrhosis is not clearly defined. This issue was addressed by evaluating renal sodium metabolism with different postures.
Methods: Renal function and plasma atrial natriuretic factor (ANF), aldosterone, and norepinephrine levels were determined after 2 hours of standing and 30, 60, and 120 minutes after taking up the supine position in 10 patients and 10 healthy subjects.
Results: When upright, patients' glomerular filtration rate and plasma ANF and norepinephrine levels did not differ from those of controls. Conversely, renal sodium excretion was reduced. Plasma aldosterone levels, which were slightly elevated, inversely correlated with renal sodium excretion. In the supine position, natriuresis increased by 308% +/- 99% in patients and 113% +/- 29% in controls (P = 0.016), so that it no longer differed between the two groups. Plasma norepinephrine and aldosterone levels decreased to a similar extent in controls and cirrhotics, whereas the increase in plasma ANF level was greater in patients. The changes in natriuresis correlated with those in plasma ANF levels and plasma aldosterone-ANF ratios in both controls and patients.
Conclusions: Aldosterone-dependent sodium retention develops in preascitic cirrhosis during standing. The supine position is the means whereby standing-induced sodium retention can be balanced.