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Abstract
BACKGROUND/AIMS 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.
- kidney
- sodium handling
- lithium clearance
- liver cirrhosis
- dopamine
- central fluid volume
Abbreviations used in this paper
- P-Na
- plasma sodium concentration
- P-K
- plasma potassium concentration
- P-Li
- plasma lithium concentration
- P-Cr
- plasma creatinine concentration
- U-Na
- urinary sodium concentration
- U-K
- urinary potassium concentration
- U-Li
- urinary lithium concentration
- U-Cr
- urinary creatinine concentration
- C-Li
- renal lithium clearance
- C-Na
- renal sodium clearance
- C-K
- renal potassium clearance
- C-Cr
- renal creatinine clearance
- FE-Na
- fractional sodium excretion
- FE-K
- fractional potassium excretion
- FE-Li
- fractional lithium excretion
- Fl-Na
- filtered sodium load
- DD
- absolute distal fluid delivery
- DDNa
- absolute distal sodium delivery
- DRNa
- absolute distal sodium reabsorption
- DFRNa I
- distal fractional sodium reabsorption I
- DFRNa II
- distal fractional sodium reabsorption II