An interventional study of Moltein PURE Protein Powder and Fluid restriction in Hyponatremia and Syndrome of Inappropriate Antidiuresis, sponsored by University Hospital, Basel, Switzerland. Recruiting at 1 site in Switzerland. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-07-10.
Sponsored by University Hospital, Basel, Switzerland · Not applicable, Interventional, and Treatment
The goal of this study is to assess the impact of protein supplementation on hyponatremia caused by the syndrome of inappropriate antidiuresis during hospitalization.
Hyponatremia (plasma sodium \<135 mmol/L) is the most common electrolyte disorder, affecting up to 30% of hospitalized patients. Chronic hyponatremia (>48 hours) is linked to longer hospital stays, higher costs, increased mortality, and morbidity (e.g., falls, fractures, cognitive deficits). The most common cause of euvolemic hyponatremia is syndrome of inappropriate antidiuresis (SIAD), characterized by excessive water retention due to dysregulated vasopressin activity. Treatment options include fluid restriction or increasing water excretion with AVP antagonists, SGLT2 inhibitors, or oral urea.
A recent trial showed that protein supplementation can induce osmotic diuresis and raise sodium levels similarly to oral urea, with better tolerability. Since protein supplementation is often used in hospitalized patients with malnutrition, this study aims to compare its acceptability to fluid restriction in hospitalized SIAD patients. This head-to-head superiority trial will randomize patients to receive either 80 g of dietary protein daily or fluid restriction (1000 mL/day) for up to 5 days. The hypothesis is that protein supplementation is significantly more acceptable to patients than fluid restriction, ultimately improving treatment outcomes.
Exclusion Criteria:
Post-randomization Exclusion Criteria:
80 g protein supplementation per day (two bottles, each containing 40 g protein)
Dietary Supplement: Moltein PURE Protein Powder
total daily fluid intake to a maximum of 1000 ml
Behavioral: Fluid restriction
80 g protein supplementation per day (two bottles, each containing 40 g protein)
total daily fluid intake to a maximum of 1000 ml
Acceptability of Intervention Measure (AIM) questionnaire
Treatment acceptability is assessed using the Acceptability of Intervention Measure (AIM) questionnaire, a validated patient-reported outcome measure scored on a 1 to 5 Likert scale. The total AIM score ranges from 4 to 20, with higher scores indicating greater acceptability. The primary analysis will compare AIM scores between the two treatment groups at the end of the intervention (day 5 or discharge).
Time frame: On day 5 (or discharge)
Plasma sodium levels
Change in change in plasma sodium levels in mmol/l will be assessed at study inclusion to day 5 of treatment or until discharge
Time frame: Daily measurements from the day of inclusion to day 5
Estimated glomerular filtration rate (eGFR)
Assessement of creatinine levels
Time frame: On the day of inclusion and on day 5
Changes in blood electrolytes
Assessement of sodium levels
Time frame: On the day of inclusion and on day 5
Changes in urine electrolytes
Assessement of sodium levels
Time frame: On the day of inclusion and on day 5
Changes in glucose levels
Assessement of glucose levels
Time frame: On the day of inclusion and on day 5
Changes kidney parameters
Assessement of urea and uric acid levels
Time frame: On the day of inclusion and on day 5
Plasma sodium levels one day after treatment start
Plasma sodium levels 12-36 hours after treatment start in patients with a plasma sodium concentration \<125 mmol/L at baseline.
Time frame: On the day of inclusion and 12-36 hours after treatment initiation
Endocrine parameters
Blood levels of copeptin, aldosterone, renin, MR-proANP and NT-proBNP, apelin, etc. are assessed
Time frame: On the day of inclusion and on day 5
General well-being
General well-being measured by numerical rating scale (NRS). Score from 0-10 while 10 indicates improved well-being
Time frame: On the day of inclusion and on day 5
Symptoms of hyponatremia
Symptoms of hyponatremia (e.g. vertigo, headache, nausea, attention deficit, mental slowness, forgetfulness, gait instability) assessed by a questionnaire (yes/no; if yes: VAS, 0-10).
Time frame: On the day of inclusion and on day 5
Fluid intake
Oral daily fluid intake assessed using a self-completed drinking protocol.
Time frame: Daily measurements from the day of inclusion to day 5
Changes in body weight
Body weight is assessed
Time frame: On the day of inclusion and on day 5
Changes in blood pressure
Systolic and diastolic blood pressure will be measured
Time frame: On the day of inclusion and on day 5
Changes in heart rate
Heart rate will be assessed
Time frame: On the day of inclusion and on day 5
Differences in clinical outcomes - length of hospital stays
Length of hospital stays will be assessed
Time frame: Daily from the day of inclusion to day 5
Need for additional hyponatremia treatment and treatment escalation
Assessment of treatment escalation (YES/NO) including: A: administration of 3% NaCl infusion; B: administration of oral urea; C administration of SGLT2 inhibitors; D: administration of vaptans; E: administration of diuretics; F: other during the treatment period.
Time frame: Daily from the day of inclusion to day 5
Treatment compliance
The participant's daily consumption of protein drinks and/or their adherence to a fluid restriction regimen is recorded.
Time frame: Daily from the day of inclusion to day 5
Quality of life (EQ-5D-5L) questionnaire
Participants' health-related quality of life is assessed using the EuroQol 5 Dimensions, 5 Levels (EQ-5D-5L) questionnaire. , which includes five dimensions: mobility, self-care, usual activities, pain/discomfort, and anxiety/depression. Each dimension is rated on five levels, ranging from no problems to extreme problems.
Time frame: On the day of inclusion and on day 5
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University Hospital, Basel, Switzerland