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Abstract: SA-OR42

Effect of Protein Supplementation on Plasma Sodium Levels and Urinary Urea Excretion in Patients with Chronic Syndrome of Inappropriate Antidiuresis (SIAD): A Monocentric Open-Label Proof-of-Concept Study

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical

Authors

  • Monnerat, Sophie, Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland
  • Atila, Cihan, Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland
  • Baur, Fabienne, Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland
  • Santos de Jesus, Joyce, Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland
  • Refardt, Julie, Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland
  • Dickenmann, Michael, Clinic for Transplantation Immunology and Nephrology, University Hospital Basel, Basel, Basel-Stadt, Switzerland
  • Christ-Crain, Mirjam, Department of Endocrinology, Diabetology and Metabolism, University Hospital Basel, Basel, Switzerland

Group or Team Name

  • Clinical Neuroendocrinology.
Background

The syndrome of inappropriate antidiuresis (SIAD) can be treated with oral urea. We hypothesized that dietary proteins could increase free-water clearance through urea-induced osmotic diuresis and aimed to investigate the effect of a high-protein supplementation on plasma sodium levels in chronic SIAD.

Methods

This is a monocentric open-label proof-of-concept trial conducted at the University Hospital of Basel, Switzerland, between 10/2021 and 02/2023. Adult outpatients with chronic SIAD received 90 g protein daily for 7 days in the form of protein powder. After a wash-out period of at least a week, patients received 30 g of oral urea daily for 7 days. The primary endpoint was the increase in sodium levels from baseline to the end of the 7-day protein supplementation.

Results

Seventeen patients were included (14 females, median age 68 [61, 79]). After 7 days of 90 g daily protein supplementation (n = 17), plasma sodium levels increased by a median of 3 mmol/l [0, 5], plasma urea by 3 mmol/l [1.7, 4.9] and urinary urea corrected for urine creatinine by 21.2 mmol/mmol [6.2, 29.1]. After 7 days of oral urea (n = 10), sodium levels increased by a median of 2 mmol/l [1, 3], plasma urea by 5.8 mmol/l [2.7, 9.2] and urinary urea corrected for urine creatinine by 31.0 mmol/mmol [18.7, 45.1].

Conclusion

Our findings suggest that a high-protein supplementation with protein powder increases plasma sodium levels in patients with chronic SIAD through protein-induced ureagenesis and osmotic diuresis. The effects are comparable to oral urea intake.

(A) Course and (B) change in plasma sodium levels, (C) plasma urea, and (D) urine urea/creatinine ratio visualized by treatment phase (protein phase in red; urea phase in blue).

Funding

  • Commercial Support – OMANDA AG (provided study material, i.e., protein powder, but not any financial support)