Validation of New Diagnostic Indices to Simplify Hyponatremia Therapy Assessment in Patients on Thiazide Diuretics

February 10, 2026 updated by: University Hospital, Basel, Switzerland

Validation of Diagnostic Indices to Simplify Hyponatremia Therapy Assessment - A Randomized, Controlled, Parallel-group Clinical Trial in Hospitalized Patients on Thiazide Diuretics (THAT Study)

This study is looking at two new parameters, aSID and ChU, to see if these can help physicians to distinguish between different causes of low sodium levels (hyponatremia) in Patients taking a medicament against high blood pressure (thiazide). Researchers also want to see if using these new parameters to decide on treatment works just as well, or better, than the current standard treatments.

Study Overview

Status

Status

Indicates the current recruitment status or the expanded access status.
Recruiting

Conditions

Conditions

The disease, disorder, syndrome, illness, or injury that is being studied. On ClinicalTrials.gov, conditions may also include other health-related issues, such as lifespan, quality of life, and health risks.

Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.

Detailed Description

Thiazide or thiazide-like diuretics associated hyponatremia (thiazide associated hyponatremia, TAH) has a high prevalence in hospitalized patients. Patients might present either with a hypovolemic hyponatremia due to volume loss as a diuretic effect of thiazide, or with a syndrome of inadequate antidiuresis (SIAD) like hyponatremia in need of fluid restriction. Canonical urine indices are not useful in differential diagnosis, being directly influenced by thiazide itself. Current guidelines suggest the use of a clinical volume status assessment, but this approach has a poor diagnostic performance, with less than 50% of patients being rightly diagnosed thru that. The investigators showed in a retrospective analysis the possible role of strong apparent ion difference (aSID) and of chloride and potassium levels in urine (ChU) in differential diagnosis of TAH. The goal of this study is to investigate prospectively whether implementation of aSID and, in case of inconclusive aSID, ChU, allows a correct differential diagnosis and treatment of TAH.

Study Type

Study Type

Describes the nature of a clinical study. Study types include interventional studies (also called clinical trials), observational studies (including patient registries), and expanded access.
Interventional

Enrollment (Estimated)

Enrollment

The number of participants in a clinical study. The "anticipated" enrollment is the target number of participants that the researchers need for the study.
136

Phase

Phase

The stage of a clinical trial studying a drug or biological product, based on definitions developed by the U.S. Food and Drug Administration (FDA). The phase is based on the study's objective, the number of participants, and other characteristics. There are five phases: Early Phase 1 (formerly listed as Phase 0), Phase 1, Phase 2, Phase 3, and Phase 4. Not Applicable is used to describe trials without FDA-defined phases, including trials of devices or behavioral interventions.
  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Contact

Study Contact

The name and contact information for the person who can answer enrollment questions for a clinical study. Each location where the study is being conducted may also have a specific contact, who may be better able to answer those questions.

Study Locations

  • Switzerland
      • Basel, Switzerland, 4031
        • Recruiting
        • University Hospital Basel
        • Contact:
        • Contact:
        • Principal Investigator:
          • Laura Potasso, Dr. med. sc.
        • Sub-Investigator:
          • Mirjam Christ-Crain, Prof. Dr. med.

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Eligibility Criteria

The key requirements that people who want to participate in a clinical study must meet or the characteristics they must have. Eligibility criteria consist of both inclusion criteria (which are required for a person to participate in the study) and exclusion criteria (which prevent a person from participating). Types of eligibility criteria include whether a study accepts healthy volunteers, has age or age group requirements, or is limited by sex.

Ages Eligible for Study

  • Adult
  • Older Adult

Accepts Healthy Volunteers

No

Description

Inclusion Criteria:

  • Hospitalized patients presenting at University Hospital Basel
  • aged 18 years or older
  • able to give informed consent as documented by signature
  • with serum sodium level < 133 mmol/l and serum osmolality < 300 mOsm/kg
  • with treatment with thiazide or thiazide-like diuretic

Exclusion Criteria:

  • symptomatic hyponatremia in need of 3% hypertonic solution or intensive care treatment
  • inability or contraindications to undergo the trial (i.e., any acute severe cardiovascular event requiring an immediate intervention)
  • decompensated liver cirrhosis CHILD C
  • decompensated heart failure NYHA III or higher
  • severe valve impairment
  • untreated adrenal insufficiency
  • severe kidney disease in need of dialysis
  • pregnancy or breastfeeding
  • end of life care
  • inability to follow the study procedures (i.e., language problem, dementia or critical illness).

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Treatment
  • Allocation: Randomized
  • Interventional Model: Parallel Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm

Participant Group / Arm

A group or subgroup of participants in a clinical trial that receives a specific intervention/treatment, or no intervention, according to the trial's protocol.
Intervention / Treatment

Intervention / Treatment

A process or action that is the focus of a clinical study. Interventions include drugs, medical devices, procedures, vaccines, and other products that are either investigational or already available. Interventions can also include noninvasive approaches, such as education or modifying diet and exercise.
Active Comparator: Standard Care Group
TAH patients randomised to the Standard Care Group will be followed by a physician not involved in the study.
Other: Standard Care
Standard diagnosis and therapy procedures at physician's discretion.
Active Comparator: aSID/ChU Guided Therapy Group
TAH patients randomised to the aSID/ChU Guided Therapy Group will have aSID and ChU determined and, depending on the results, will be assigned to fluid administration with saline or drinking restriction.
Other: aSID/ChU Guided Therapy

Stopping of thiazide therapy. Measure aSID:

  • aSID between 39 and 42 mmol/l : measure ChU

    • ChU lower than 15mmol/l : fluid administration (0.9% NaCl infusion, 250-500 ml over 2 hours followed by 10-20 ml/kg/24h)
    • ChU higher than 14.9 mmol/l : drinking restriction (of at least 50% of usual drinking volume)
  • aSID higher than 42 mmol/l : fuid administration (fluid administration (0.9% NaCl infusion, 250-500 ml over 2 hours followed by 10-20 ml/kg/24h)
  • aSID lower than 39 mmol/l : drinking restriction (of at least 50% of usual drinking volume)

The aSID/ChU guided therapy will take place for a minimum of 1- and a maximum of 3 days after enrolment. Treatment and adherence to the treatment will be assessed and re-evaluated at least daily for 3 days or till discharge or sodium normalization.

What is the study measuring?

Primary Outcome Measures

Primary Outcome Measures

In a clinical study's protocol, the planned outcome measure that is the most important for evaluating the effect of an intervention/treatment. Most clinical studies have one primary outcome measure, but some have more than one.
Outcome Measure
Measure Description
Time Frame
Serum Sodium Level
Time Frame: at baseline, 24 hours and up to 72 hours
Percentage of patients with an increase in serum sodium level > 4 mmol/l at day 1 or > 134 mmol/l in maximum 3 days in the aSID/ChU guided therapy group as compared to the standard care (control) group.
at baseline, 24 hours and up to 72 hours

Secondary Outcome Measures

Secondary Outcome Measures

In a clinical study's protocol, a planned outcome measure that is not as important as the primary outcome measure for evaluating the effect of an intervention but is still of interest. Most clinical studies have more than one secondary outcome measure.
Outcome Measure
Measure Description
Time Frame
Descriptive analyses: Changes in aSID in relation to changes in serum sodium levels
Time Frame: at baseline, 24 hours and up to 72 hours
Descriptive analyses: Changes in aSID in relation to changes in serum sodium levels.
at baseline, 24 hours and up to 72 hours
Descriptive analyses: Changes in ChU in relation to changes in serum sodium levels
Time Frame: at baseline, 24 hours and up to 72 hours
Descriptive analyses: Changes in ChU in relation to changes in serum sodium levels.
at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: aSID and ChU
Time Frame: at baseline, 24 hours and up to 72 hours
Sensibility, specificity, negative predictive value and positive predictive value at different cut-offs for adequate therapy of TAH. An adequate therapy of TAH is a therapy by which the patient reaches the primary endpoint independent from randomization arm.
at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: aSID measured in blood gas analysis
Time Frame: at baseline, 24 hours and up to 72 hours
Sensibility, specificity, negative predictive value and positive predictive value at different cut-offs for adequate therapy of TAH. An adequate therapy of TAH is a therapy by which the patient reaches the primary endpoint independent from randomization arm.
at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: clinical volume status assessment
Time Frame: at baseline, 24 hours and up to 72 hours
Sensibility, specificity, negative predictive value and positive predictive value at different cut-offs for adequate therapy of TAH. An adequate therapy of TAH is a therapy by which the patient reaches the primary endpoint independent from randomization arm.
at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: not-invasive instrumental volume status assessment
Time Frame: at baseline, 24 hours and up to 72 hours
Sensibility, specificity, negative predictive value and positive predictive value at different cut-offs for adequate therapy of TAH. An adequate therapy of TAH is a therapy by which the patient reaches the primary endpoint independent from randomization arm.
at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: other hormones such as aldosterone, renin, arginine-vasopressin
Time Frame: at baseline, 24 hours and up to 72 hours
Sensibility, specificity, negative predictive value and positive predictive value at different cut-offs for adequate therapy of TAH. An adequate therapy of TAH is a therapy by which the patient reaches the primary endpoint independent from randomization arm.
at baseline, 24 hours and up to 72 hours

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Sponsor

The organization or person who initiates the study and who has authority and control over the study.
University Hospital, Basel, Switzerland

Investigators

Investigators

A researcher involved in a clinical study. Related terms include site principal investigator, site sub-investigator, study chair, study director, and study principal investigator.
  • Principal Investigator: Laura Potasso, Dr. med. sc., University Hospital, Basel, Switzerland

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

Study Start

The actual date on which the first participant was enrolled in a clinical study. The "anticipated" study start date is the date that the researchers think will be the study start date.
May 6, 2024

Primary Completion (Estimated)

Primary Completion

The date on which the last participant in a clinical study was examined or received an intervention to collect final data for the primary outcome measure. Whether the clinical study ended according to the protocol or was terminated does not affect this date. For clinical studies with more than one primary outcome measure with different completion dates, this term refers to the date on which data collection is completed for all the primary outcome measures. The "anticipated" primary completion date is the date that the researchers think will be the primary completion date for the study.
April 1, 2027

Study Completion (Estimated)

Study Completion

The date on which the last participant in a clinical study was examined or received an intervention/treatment to collect final data for the primary outcome measures, secondary outcome measures, and adverse events (that is, the last participant's last visit). The "anticipated" study completion date is the date that the researchers think will be the study completion date.
April 1, 2027

Study Registration Dates

First Submitted

First Submitted

The date on which the study sponsor or investigator first submitted a study record to ClinicalTrials.gov. There is typically a delay of a few days between the first submitted date and the record's availability on ClinicalTrials.gov (the first posted date).
April 16, 2024

First Submitted That Met QC Criteria

First Submitted That Met QC Criteria

The date on which the study sponsor or investigator first submits a study record that is consistent with National Library of Medicine (NLM) quality control (QC) review criteria. The sponsor or investigator may need to revise and submit a study record one or more times before NLM's QC review criteria are met. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
April 19, 2024

First Posted (Actual)

First Posted

The date on which the study record was first available on ClinicalTrials.gov after National Library of Medicine (NLM) quality control (QC) review has concluded. There is typically a delay of a few days between the date the study sponsor or investigator submitted the study record and the first posted date.
April 24, 2024

Study Record Updates

Last Update Posted (Actual)

Last Update Posted

The most recent date on which changes to a study record were made available on ClinicalTrials.gov. There may be a delay between when the changes were submitted to ClinicalTrials.gov by the study's sponsor or investigator (the last update submitted date) and the last update posted date.
February 11, 2026

Last Update Submitted That Met QC Criteria

Last Update Submitted That Met QC Criteria

The most recent date on which the study sponsor or investigator submitted changes to a study record that are consistent with National Library of Medicine (NLM) quality control (QC) review criteria. It is the responsibility of the sponsor or investigator to ensure that the study record is consistent with the NLM QC review criteria.
February 10, 2026

Last Verified

Last Verified

The most recent date on which the study sponsor or investigator confirmed the information about a clinical study on ClinicalTrials.gov as accurate and current. If a study with a recruitment status of recruiting; not yet recruiting; or active, not recruiting has not been confirmed within the past 2 years, the study's recruitment status is shown as unknown.
February 1, 2026

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

Other Study ID Numbers

Identifiers or ID numbers other than the NCT number that are assigned to a clinical study by the study's sponsor, funders, or others. These numbers may include unique identifiers from other trial registries and National Institutes of Health grant numbers.
  • 2024-00335; kt23ChristCrain4

Plan for Individual participant data (IPD)

Plan to Share Individual Participant Data (IPD)?

UNDECIDED

Drug and device information, study documents

Studies a U.S. FDA-regulated drug product

No

Studies a U.S. FDA-regulated device product

No

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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