Thiazide Associated HyponatremiaNCT06381934

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

A study testing aSID/ChU Guided Therapy in people with Thiazide Associated Hyponatremia, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.

Recruiting

Looking for participants now. Contact the study team or a site below to ask about taking part.

Sites and contacts

Official record

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Trial summary

Who is it for?: Ages 18 years and older
Conditions the study is for: Thiazide Associated Hyponatremia
What is being tested?: aSID/ChU Guided Therapy
Type of treatment: Injection or infusion
Could I receive a placebo?: No, everyone receives an active treatment
How many people: 136 participants
Where: 1 siteSwitzerland
Study dates: 6 May 2024to Apr 2027
Phase: Interventional
Are there results?: Not yet: the study is under way

Key requirements

Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.

Ages 18 years and older
All sexes
No healthy volunteers
Adult, Older adult

Who may be able to join

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

Who cannot join

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

Show all 10Show fewer

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).

Trial locations and contacts

1 site in 1 country. Contact the study team or a site near you to ask about taking part.

Laura Potasso, Dr. med. sc. contact

+41 61 328 58 76

laura.potasso@usb.ch

Switzerland1 site, 1 recruiting

University Hospital Basel
Basel, 4031
Laura Potasso, Dr. med. sc., +41 61 328 58 76, laura.potasso@usb.ch
Mirjam Christ-Crain, Prof. Dr. med., +41 61 328 70 80, mirjam.christ-crain@usb.ch
Recruiting

Other trials in Switzerland

About this study

Official title: 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.

Read the 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.

Conditions: Thiazide Associated Hyponatremia
Being tested: Standard Care, aSID/ChU Guided Therapy
Keywords: Hyponatremia, Strong Apparent Ion Difference, Potassium Levels in Urine
Medical subject headings: Hyponatremia

What participants receive

What participants receive. In a randomised study each person is assigned to one group by chance.

Standard CareOther
Standard diagnosis and therapy procedures at physician's discretion.
aSID/ChU Guided TherapyOther
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.

Study groups in NCT06381934
Study group	Role	What they receive
Standard Care Group	Active comparator	TAH patients randomised to the Standard Care Group will be followed by a physician not involved in the study. Receives: Other: Standard Care
aSID/ChU Guided Therapy Group	Active comparator	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. Receives: Other: aSID/ChU Guided Therapy

What is being measured

The primary outcome is the main question the study is designed to answer.

Serum Sodium Level
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.
Measured: at baseline, 24 hours and up to 72 hours

Secondary outcomes (7)

Descriptive analyses: Changes in aSID in relation to changes in serum sodium levels
Descriptive analyses: Changes in aSID in relation to changes in serum sodium levels.
Measured: at baseline, 24 hours and up to 72 hours
Descriptive analyses: Changes in ChU in relation to changes in serum sodium levels
Descriptive analyses: Changes in ChU in relation to changes in serum sodium levels.
Measured: at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: aSID and ChU
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.
Measured: at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: aSID measured in blood gas analysis
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.
Measured: at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: clinical volume status assessment
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.
Measured: at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: not-invasive instrumental volume status assessment
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.
Measured: at baseline, 24 hours and up to 72 hours
Diagnostic performance analyses of: other hormones such as aldosterone, renin, arginine-vasopressin
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.
Measured: at baseline, 24 hours and up to 72 hours

Timeline

From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.

6 May 2024Apr 2027

First posted24 Apr 2024
Study start6 May 2024
Primary completionApr 2027 (estimated)
Study completionApr 2027 (estimated)

Resources

Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
Publications (1)Papers the sponsor has linked to this study.
Other trials for Thiazide Associated HyponatremiaStudies of the same condition, open and under way.
More trials run by University Hospital, Basel, SwitzerlandThe sponsor's other registered studies.
What the trial phases meanHow a treatment moves from first tests in people to approval.

More details

For doctors and researchers: how the study is designed, who runs it, and its registry IDs.

Study design

Study type: Interventional
Phase: Phase N/A
Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: None (open label)
Enrolment: 136 participants (estimated)

IDs, dates and publications

ClinicalTrials.gov ID: NCT06381934
Sponsor's protocol ID: 2024-00335; kt23ChristCrain4
Status last verified: Feb 2026
First submitted: 16 Apr 2024
Last updated: 11 Feb 2026
Results posted: No
Data monitoring committee: No
FDA-regulated drug: No
FDA-regulated device: No
Individual data sharing: Undecided

Publications

Vogt K, Widmer D, Kirsch M, Christ-Crain M, Potasso L. Validation of new diagnostic indices to simplify hyponatremia therapy assessment in patients on thiazide diuretics: study protocol of a randomized, controlled, parallel-group trial (THAT-Study). Trials. 2025 Jul 11;26(1):242. doi: 10.1186/s13063-025-08925-4.
PubMed 40646556

Study at a glance

From the registry record, last updated by the sponsor on 11 Feb 2026. Recruitment status is as the sponsor reported it: confirm with the study team.

Official title: Validation of Diagnostic Indices to Simplify Hyponatremia Therapy Assessment - A Randomized, Controlled, Parallel-group Clinical Trial in Hospitalized Patients on Thiazide Diuretics (THAT Study)
ClinicalTrials.gov ID: NCT06381934
Acronym / sponsor ID: 2024-00335; kt23ChristCrain4
Conditions: Thiazide Associated Hyponatremia
Keywords: Hyponatremia, Strong Apparent Ion Difference, Potassium Levels in Urine
Study type: Interventional
Recruitment status: Recruiting
Enrolment: 136 participants (estimated)
Lead sponsor: University Hospital, Basel, SwitzerlandUniversity, hospital or other
Study start: 6 May 2024 (actual)
Primary completion: Apr 2027 (estimated)
Study completion: Apr 2027 (estimated)
First posted: 24 Apr 2024 (actual)
Results: Not posted in the source record

Clinical summary

The research question as the sponsor registered it. This describes what the study plans to test, not what it found.

Detailed description

Study design

Primary purpose: Treatment
Allocation: Randomised
Intervention model: Parallel groups
Masking: None (open label)
Number of arms: 2

Arm	Type	Receives
Standard Care Group	Active comparator	Other: Standard CareTAH patients randomised to the Standard Care Group will be followed by a physician not involved in the study.
aSID/ChU Guided Therapy Group	Active comparator	Other: aSID/ChU Guided TherapyTAH 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.

Who may qualify

Ages: 18 years and older
Sex: All
Healthy volunteers: Not accepted
Age groups: Adult, Older adult

Key inclusion criteria (5 listed)

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

Key exclusion criteria (10 listed)

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

Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.

Interventions

Intervention	Type	Arms
Standard CareStandard diagnosis and therapy procedures at physician's discretion.	Other	Standard Care Group
aSID/ChU Guided TherapyStopping 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.	Other	aSID/ChU Guided Therapy Group

Primary outcome

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.

7 secondary outcomes

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 ChU in relation to changes in serum sodium levels
Time frame: 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
Diagnostic performance analyses of: aSID measured in blood gas analysis
Time frame: 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
Diagnostic performance analyses of: not-invasive instrumental volume status assessment
Time frame: 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

Results and safety

This study is still under way. Results are not available in the source record yet.

Research links

Official record on ClinicalTrials.govLast updated by the sponsor 11 Feb 2026.
Derived from this study: PubMed 40646556Vogt K, Widmer D, Kirsch M, Christ-Crain M, Potasso L. Validation of new diagnostic indices to simplify hyponatremia therapy assessment in patients on thiazide diuretics: study protocol of a randomized, controlled, parallel-group trial (THAT-Study). Trials. 2025 Jul 11;26(1):242. doi: 10.1186/s13063-025-08925-4.
Individual participant dataSharing planned: Undecided

Referral and contact

AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part.

Laura Potasso, Dr. med. sc. contact

+41 61 328 58 76

laura.potasso@usb.ch

Laura Potasso, Dr. med. sc. principal investigator

University Hospital, Basel, Switzerland

1 site in 1 country: see every site and its status.

Questions about this trial

What is this clinical trial studying?

A study testing aSID/ChU Guided Therapy in people with Thiazide Associated Hyponatremia, run by University Hospital, Basel, Switzerland at 1 site in Switzerland.

The full registered description is in the About this study section and the official record.

Who may be eligible to take part?

The sponsor lists 5 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.

Is this clinical trial currently recruiting?

The record says: looking for participants now, as of the sponsor's last update on 11 Feb 2026. Status can change between updates, so confirm with the study contact before making plans.

Where is the study taking place?

The record lists 1 site in Switzerland. Whether a site is taking part right now should be confirmed with that site. See every site.

What are the possible benefits and risks?

They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.

Are results available for this study?

This study is still under way. Results are not available in the source record yet.

How can a doctor refer a patient or contact the research team?

Contact Laura Potasso, Dr. med. sc. (+41 61 328 58 76, laura.potasso@usb.ch), or a site near the patient. AzTrials does not enrol participants or take referrals.

What does the primary outcome measure?

Serum Sodium Level (time frame: at baseline, 24 hours and up to 72 hours). It is what the study was designed to measure, not a finding.

Where can I read the original study information?

On the ClinicalTrials.gov record for NCT06381934, which also lists 1 linked publication.

Does a listing mean the treatment is approved or proven to work?

No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.

How often is this information updated?

AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 11 Feb 2026.