Salt intake and renal outcome in patients with progressive renal disease.
Experimental studies suggest that salt intake plays a critical role in the progressive glomerular filtration rate (GFR) loss of established renal disease; however, this issue has never been addressed in humans. To this aim, we have retrospectively analyzed the clinical data of patients with chronic renal failure (CRF), in whom a low-protein diet was prescribed, over a period of about 3 years. On the basis of the daily urinary sodium output, the patients were divided into two groups: a group of patients constantly ingesting > 200 mEq NaCl/day (high sodium intake, HSD, n = 30) and a group in which salt intake was < 100 mEq/day (low sodium intake, LSD, n = 27). Patients taking diuretics or ACE inhibitors were excluded. At baseline, the LSD group, as compared to the HSD group, was characterized by significantly lower creatinine clearance (24 +/- 2 vs. 28 +/- 2 ml/min) and higher proteinuria (2.9 +/- 0.3 vs. 1.5 +/- 0.2 g/day). Despite the presence of these risk factors for progression, and a similar control of blood pressure (the average of the mean arterial pressure during follow-up was 111 +/- 2 mm Hg in LSD and 107 +/- 2 mm Hg in HSD), the LSD patients showed a better renal outcome: in this group, as compared to HSD, the GFR decline was lower (0.25 +/- 0.07 vs. 0.51 +/- 0.09 ml/min/month, p < 0.05), and proteinuria did not change while it markedly increased in HSD. During follow-up, LSD patients also ingested a significantly lower amount of protein. This study therefore suggests that efficacious salt restriction in CRF patients improves the outcome of renal disease independent from its antihypertensive effects.
Cianciaruso
B
B
Nephrology Division, School of Medicine, I and II University of Naples, Italy. cianciar@unina.it
Bellizzi
V
V
Minutolo
R
R
Tavera
A
A
Capuano
A
A
Conte
G
G
De Nicola
L
L
D001794:Blood Pressure; D003404:Creatinine / Q000652:urine; D018753:Diet, Protein-Restricted; D004039:Diet, Sodium-Restricted; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D007676:Kidney Failure, Chronic / Q000178:diet therapy* / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D009318:Natriuresis; D011507:Proteinuria; D012189:Retrospective Studies; D012982:Sodium, Dietary / Q000008:administration & dosage; D016896:Treatment Outcome
D012982:Sodium, Dietary; D003404:Creatinine