New diagnostic methods for treating low sodium levels in patients on thiazide diuretics

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

Not applicable Interventional University Hospital, Basel, Switzerland · NCT06381934

This study is testing two new ways to help doctors figure out why patients on thiazide diuretics have low sodium levels, to see if it can lead to better treatment options.

Quick facts

PhaseNot applicable
Study typeInterventional
Enrollment136 (estimated)
Ages18 Years and up
SexAll
SponsorUniversity Hospital, Basel, Switzerland Academic / other
Locations1 site (Basel)
Trial IDNCT06381934 on ClinicalTrials.gov

What this trial studies

This study evaluates two new diagnostic parameters, strong apparent ion difference (aSID) and chloride and potassium levels in urine (ChU), to improve the differentiation of causes of hyponatremia in patients taking thiazide diuretics. The goal is to determine if these new indices can enhance the accuracy of diagnosis and treatment compared to current standard methods, which have shown poor performance. By prospectively implementing these parameters, researchers aim to provide better treatment strategies for hospitalized patients suffering from thiazide-associated hyponatremia.

Who should consider this trial

Good fit: Ideal candidates include hospitalized patients aged 18 and older who are on thiazide diuretics and have low serum sodium levels.

Not a fit: Patients with severe symptomatic hyponatremia requiring immediate intervention or those with significant comorbidities may not benefit from this study.

Why it matters

Potential benefit: If successful, this study could lead to more accurate diagnoses and improved treatment options for patients with low sodium levels caused by thiazide diuretics.

How similar studies have performed: While the approach of using aSID and ChU is novel, previous studies have indicated potential benefits in differentiating causes of hyponatremia, suggesting a promising avenue for further investigation.

Eligibility criteria

Show full inclusion / exclusion criteria
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).

Where this trial is running

Basel

Study contacts

How to participate

  1. Review the eligibility criteria above with your treating physician.
  2. Visit the official trial page on ClinicalTrials.gov for the most current contact information and recruitment status.
  3. Contact the listed study coordinator or principal investigator to request pre-screening. Pre-screening is free and never obligates you to enroll.
Conditions Thiazide Associated HyponatremiaHyponatremiaStrong Apparent Ion DifferencePotassium Levels in Urine
Last reviewed 2026-06-13 by the Find a Trial editorial team. Information on this page is for educational purposes and is not medical advice. Always consult qualified healthcare professionals about clinical trial participation.