Characterization of the renin-aldosterone system in decompensated cirrhosis.

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Abstract
The NI [water immersion to the neck] model was used to assess responsiveness of PRA [plasma renin activity] and PA [plasma aldosterone] in cirrhosis. Cirrhotic patients [16] were studied twice while in balance on a 10 meq Na, 100 meq K diet, under control conditions and during NI. Conditions of seated posture and time of day were identical. Plasma for PRA and PA was obtained at 30 min intervals for 6 h. NI produced profound suppression of PRA as early as 60 min with maximal suppression (70%) by 150 min (P < 0.005). Recovery from NI was associated with a prompt return to prestudy levels. PA was suppressed within 60 min with a maximal suppression of 59% by 240 min (P < 0.005) and a prompt return to prestudy levels during recovery. Suppression of PA paralleled that of PRA throughout the immersion period (P < 0.005). Although 15 of the 16 subjects manifested a significant suppression of PA, 8 subjects manifested either a blunted or absent natriuretic response during NI. Apparently elevated PRA and PA levels of cirrhosis are suppressed promptly and markedly in response to a standardized volume stimulus. Parallelism of changes in PRA and PA supports the importance of the renin-angiotensin axis in control of volume-regulated changes in PA in cirrhotic man. The dissociation between the marked suppression of circulating PA and absence of a natriuresis in 8 of these subjects suggests that aldosterone may play only a permissive role in relation to the impaired Na excretion of cirrhosis.