An interventional study of Water administration and NaCl-Administration in Hyponatremia, sponsored by University of Cologne. Recruiting at 1 site in Germany. Open to participants aged 18 Years and older. Per ClinicalTrials.gov, last updated 2025-09-17.
Sponsored by University of Cologne · Not applicable, Interventional, and Basic science
Hyponatremia is the most common electrolyte disorder of all and can be observed in more than 30% of all patients in hospitals. Osmotic homeostasis of body fluids is essential for survival of all living creatures. It is widely accepted that extra- and intracellular osmolalities are in equilibrium at all times and thus, changes in the extracellular osmolality will lead to either shrinkage or swelling of cells which can be detrimental. In severe cases, it can lead to swelling of the brain and death. Even in less dramatic scenarios, symptoms such as epileptic seizures, headaches, depression and dizziness exist, leading to an increased risk of fractures, hospital admissions and a considerable burden for affected patients.
As short-term defense against osmotic stress, each individual cell is capable of actively externalizing or internalizing osmotically active solutes which restores normal or near-normal cell volume at the expense of an altered milieu interior. Obviously, there must be limitations to this strategy if intracellular integrity is meant to be kept stable. It has therefore been postulated that, apart from this cell-immanent mechanism, extracellular and intracellular electrolyte stores could assist in buffering osmotic imbalances.
The Edelman formula states that extracellular sodium is determined by the total amount of exchangeable body sodium (the major extracellular cation) plus potassium (the major intracellular cation) divided by total body water. Several studies have shown, that it only partially explains the changes in patients outside the osmotic equilibrium.
To better understand these physiological responses might not only promote the researcher's insight into the most basic cellular self-defense systems by measuring and comparing extra- and intracellular electrolyte concentrations with estimated changes in a patient that will be intravenously challenged with either water or sodium chloride 3%.
The evolution over time of extra- and intracellular sodium and other electrolytes will be assessed quantitatively in patients with impaired renal function after water or sodium chloride (NaCl) administration.
164 studies on the registry are indexed under Hyponatremia; 16 are open to participants now.
This study's planned enrollment of 60 is close to the median of 60 across 98 interventional studies indexed under Hyponatremia.
Browse Hyponatremia studies →University of Cologne is the lead sponsor of 203 studies on the registry; 26 are open to participants now.
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Exclusion Criteria:
Underlined terms in the criteria open these too. Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
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You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Informed consent
Before you join, the study team explains what taking part involves — its purpose, what happens, the risks and possible benefits — and answers your questions, so you can decide freely. Consent is usually recorded on a form (the informed consent form, ICF) signed by you or, where the law allows, by someone legally authorised to decide for you.
You can keep asking questions during the study, you are told of new information that matters, and you can choose to leave at any time.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
NYHA class (heart failure)
The New York Heart Association’s four classes of how much heart failure limits physical activity.
Studies set their own limit — many outside heart failure leave out class III–IV, while heart failure studies may ask for a particular class. Check the class this study names.
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Hemoglobin (Hb)
The protein in red blood cells that carries oxygen. A low level is anaemia, which can cause tiredness and breathlessness. Measured in g/dL or g/L (9 g/dL is 90 g/L).
Explained by clinicaltrials.gg, not part of the registry record. The study team decides who can take part.
Intravenous administration of water (Aqua ad injectabilia) until a decrease of plasma sodium of 5 to 8 mmol/l has been achieved
Other: Water administration
Intravenous administration of NaCl 3% until an increase of plasma sodium of 5 to 8 mmol/l has been achieved
Other: NaCl-Administration
Intravenous administration of water (Aqua ad injectabilia) until a decrease of plasma sodium of 5 to 8 mmol/l has been achieved
Intravenous administration of NaCl 3% until an increase of plasma sodium of 5 to 8 mmol/l has been achieved
acute changes of extracellular osmolality
The primary aim is to compare the actual acute change of extracellular sodium with the estimated change of extracellular sodium in response to an intravenous challenge with either water or sodium. Precise evaluation of the validity of the concept of Edelman in acute changes of extracellular osmolality
Time frame: 300 minutes after infusion
change of extracellular electrolyte concentrations
extracellular electrolyte concentrations in response to an intravenous challenge with either water or sodium.
Time frame: 300 minutes after infusion
change of intracellular electrolyte concentrations
intracellular (red blood cells/white blood cells) electrolyte concentrations in response to an intravenous challenge with either water or sodium.
Time frame: 300 minutes after infusion
change of osmolality
change of osmolality in response to an intravenous challenge with either water or sodium
Time frame: 300 minutes after infusion
change of cell volume
cell volume (red blood cells) in response to an intravenous challenge with either water or sodium
Time frame: 300 minutes after infusion
Started Jul 2023 (actual). Primary completion is estimated for May 2026, 34 months after the start.
Of 24 interventional studies with no phase under Hyponatremia, half reached primary completion within 24 months of starting (the median), counting those still running; a quarter within 12 and three quarters within 48. This study's planned 34 months is above that.
How these figures are worked out, and which studies are left out of them.
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