Effekt einer Eiweißsupplementierung auf den Natrium-Spiegel im Blut und der Harnstoffausscheidung im Urin bei Patienten mit einem Syndrom der inadäquaten Antidiurese – eine monozentrische offene Studie -Die TREASURE Studie

Dietary Supplement: Protein supplementation;Dietary Supplement: Oral urea

Inclusion Criteria:

- previous documented diagnosis of chronic SIAD

- confirmed diagnosis of SIAD at screening visit defined as:

- plasma sodium concentration <135 mmol/L, measured in lithium heparin plasma

- Plasma osmolality <300 mOsm/kg

- Urine osmolality >100 mOsm/kg

- Urine sodium concentration >30mmol/l

- Clinical euvolemia, defined as an absence of signs of hypovolemia (orthostasis,
tachycardia, decreased skin turgor, dry mucous membranes) or hypervolemia (edema,
ascites)

Exclusion Criteria:

- lactose intolerance, celiac disease, milk protein allergy, soja allergy, nuts allergy
or known hypersensitivity or allergy to one of the components of the protein
supplementation (Whey Protein®, foodspring GmbH, Germany or Clear Whey Isolate®,
MyProtein THG Company, United Kingdom)

- inborn metabolic disorders implying carbohydrate, lipid or protein metabolism - severe
symptomatic hyponatremia in need of treatment with 3% NaCl-solution or in need of
intensive/intermediate care treatment at time of inclusion

- Risk factors for osmotic demyelination syndrome: hypokalaemia (K <3,4 mmol/L),
malnutrition, advanced liver disease, alcoholism.

- contraindication for lowering blood pressure

- type 1 diabetes mellitus

- uncontrolled type 2 diabetes mellitus (defined as HbA1c >8.0%)

- uncontrolled hypothyroidism

- uncontrolled adrenal insufficiency

- reduction of eGFR <60 mL/min/1,73 m2 (KDIGO G3, G4 and G5) or end stage renal disease
(dialysis)

- severe hepatic impairment (ALAT/ASAT >3x upper limit) or advanced symptomatic liver
disease defined as past or current hepatic encephalopathy, liver cirrhosis Child C or
decompensated (bleeding, jaundice, hepatorenal syndrome).

- treatment with a diuretic, a SGLT2 inhibitor or a corresponding combined preparation,
lithium chloride, urea, vaptans, demeclocycline in the two weeks before screening.

- severe immunosuppression defined as leucocytes <2G

- pregnancy, wish to become pregnant during study period or breastfeeding

- end of life care

- Inability to follow the procedures of the study, e.g. due to language problems,
psychological disorders, dementia, etc.

- Current participation in another intervention study

- lack of capacity or other reason preventing from giving informed consent or following
study procedures.