Renal distal tubular handling of sodium in central fluid volume homoeostasis in preascitic cirrhosis.
OBJECTIVE
Patients with preascitic liver cirrhosis have an increased central plasma volume, and, for any given plasma aldosterone concentration, they excrete less sodium than healthy controls. A detailed study of the distribution of sodium reabsorption along the segments of the renal tubule, especially the distal one, is still lacking in preascitic cirrhosis.


METHODS
Twelve patients with Child-Pugh class A cirrhosis and nine control subjects (both groups on a normosodic diet) were submitted to the following investigations: (a) plasma levels of active renin and aldosterone; (b) four hour renal clearance of lithium (an index of fluid delivery to the loop of Henle), creatinine, sodium, and potassium; (c) dopaminergic activity, as measured by incremental aldosterone response to intravenous metoclopramide.


RESULTS
Metoclopramide induced higher incremental aldosterone responses, indicating increased dopaminergic activity in patients than controls, which is evidence of an increased central plasma volume (+30 min: 160.2 (68.8) v 83.6 (35.2) pg/ml, p<0.01; +60 min: 140.5 (80.3) v 36. 8 (36.1) pg/ml, p<0.01). Patients had increased distal fractional sodium reabsorption compared with controls (26.9 (6.7)% v 12.5 (3. 4)% of the filtered sodium load, p<0.05). In the patient group there was an inverse correlation between: (a) absolute distal sodium reabsorption and active renin (r -0.59, p<0.05); (b) fractional distal sodium reabsorption and sodium excretion (r -0.66, p<0.03).


CONCLUSIONS
These data suggest that in preascitic cirrhosis the distal fractional tubular reabsorption of sodium is increased and critical in regulating both central fluid volume and sodium excretion.
Sansoè
G
G
Gastroenterology Unit, Gradenigo Hospital, Torino, Italy.
Ferrari
A
A
Baraldi
E
E
Castellana
C N
CN
De Santis
M C
MC
Manenti
F
F
D000328:Adult; D000368:Aged; D000450:Aldosterone / Q000097:blood; D016022:Case-Control Studies; D003404:Creatinine / Q000378:metabolism; D018492:Dopamine Antagonists; D005260:Female; D006801:Humans; D007686:Kidney Tubules, Distal / Q000378:metabolism*; D008094:Lithium / Q000378:metabolism; D008103:Liver Cirrhosis / Q000378:metabolism*; D008297:Male; D008657:Metabolic Clearance Rate; D008787:Metoclopramide; D008875:Middle Aged; D011188:Potassium / Q000378:metabolism; D012083:Renin / Q000097:blood; D012964:Sodium / Q000378:metabolism*
D018492:Dopamine Antagonists; D000450:Aldosterone; D008094:Lithium; D012964:Sodium; D003404:Creatinine; D012083:Renin; D008787:Metoclopramide; D011188:Potassium