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BACKGROUND/AIMS: Previous studies in preascitic cirrhosis demonstrated sodium retention during upright posture and sodium hyperexcretion during bed-rest. In patients with ascites, sodium excretion and creatinine clearance decreased during upright posture. Head-down tilting (HDT) accentuated the natriuretic effect of bed-rest in short term studies. The aim of this study was to evaluate the effects of prolonged change in posture on sodium homeostasis and on haemodynamics in cirrhotic patients. METHODS: Eighteen cirrhotic patients (9 with, 9 without ascites), were studied during 12 h upright, supine and HDT position (-10 degrees). During each position, 12 h urine collections were performed and blood samples were obtained before and after change in position. Non-invasive systemic hemodynamic measurements were performed. RESULTS: There was no significant difference between HDT and supine position in both ascitic and preascitic groups for urinary volume, fractional sodium excretion, creatinine clearance, urinary and plasma hormones and hemodynamics. Urinary volume (in supine and HDT) and fractional sodium excretion (in supine) were significantly higher and urinary noradrenaline and plasma renin (in supine and HDT) significantly lower in the preascitic group compared with the ascitic patients. Cardiac output and heart rate decreased after 12 h supine and HDT, suggesting a deactivation of sympatic nervous system and catecholamines. CONCLUSION: Our results demonstrate that prolonged HDT had no advantage over normal bed-rest in both patient groups. Possibly, a short-term beneficial effect of HDT was lost after several hours.