Low-Osmolar Diet and Adjusted Water Intake for Vasopressin Reduction in Autosomal Dominant Polycystic Kidney Disease: A Pilot Randomized Controlled Trial

Am J Kidney Dis. 2016 Dec;68(6):882-891. doi: 10.1053/j.ajkd.2016.07.023. Epub 2016 Sep 20.

Abstract

Background: Autosomal dominant polycystic kidney disease (ADPKD) affects millions of people worldwide. Vasopressin promotes disease progression.

Study design: A randomized controlled trial with equal (1:1) allocation.

Setting & participants: This trial examined the effect of combining a low-osmolar (low-sodium [1,500mg/d], low-protein [0.8g per kilogram of body weight]) diet and adjusted water intake on vasopressin secretion in 34 patients with ADPKD.

Intervention: Participants were randomly assigned to receive a low-osmolar diet followed by adjusted water intake to achieve urine osmolality ≤ 280mOsm/kg water versus no intervention for 2 weeks.

Outcome: The primary outcome of the study was change (delta) in copeptin levels and urine osmolality between the intervention and control groups from baseline to 2 weeks.

Measurements: Fasting plasma copeptin level, 24-hour urine osmolality, and total solute intake.

Results: Baseline characteristics of the 2 groups were similar. Mean plasma copeptin levels and urine osmolality declined from 6.2±3.05 (SD) to 5.3±2.5pmol/L (P=0.02) and from 426±193 to 258±117mOsm/kg water (P=0.01), respectively, in the intervention group compared to a nonsignificant change in the control group (from 4.7±3.6 to 5.07±4pmol/L [P=0.2] and 329±159 to 349±139mOsm/kg water [P=0.3], respectively). The change in copeptin levels (primary outcome) and urine osmolality was statistically significant between the intervention and control groups (delta copeptin, -0.86±1.3 vs +0.39±1.2pmol/L [P=0.009]; delta urine osmolality, -167±264 vs +20±80mOsm/kg water [P=0.007], respectively). Total urinary solute decreased in only the intervention group and significantly differed between groups at week 1 (P=0.03), reducing mean water prescription from 3.2 to 2.6L/d.

Limitations: Small sample size and short follow-up.

Conclusions: We developed a stepwise dietary intervention that led to a significant reduction in vasopressin secretion in patients with ADPKD. Furthermore, this intervention led to a reduction in water required for vasopressin reduction.

Keywords: Autosomal dominant polycystic kidney disease (ADPKD); clinical trial; copeptin; nutrition; osmolality; protein; salt; urea; vasopressin; water.

Publication types

  • Randomized Controlled Trial

MeSH terms

  • Adolescent
  • Adult
  • Arginine Vasopressin / metabolism*
  • Arginine Vasopressin / urine
  • Drinking*
  • Female
  • Humans
  • Male
  • Middle Aged
  • Osmolar Concentration
  • Pilot Projects
  • Polycystic Kidney, Autosomal Dominant / diet therapy*
  • Polycystic Kidney, Autosomal Dominant / urine
  • Young Adult

Substances

  • Arginine Vasopressin