Copeptin Measurement After Mannitol and Hypertonic Saline for the Diagnosis of Polyuria-polydipsia Syndrome
For patients and families
In plain language
An automatic summary of structured registry data. It is an orientation aid, not a substitute for the official protocol or a physician assessment.
- What is being studied
- The protocol lists: Mannitol, Hypertonic Saline.
- Who it may be relevant to
- Registry conditions: Arginine Vasopressin Deficiency, Primary Polydipsia. Basic parameters: from 18 years · All.
- What needs checking
- Age, condition and sex are only basic indicators. Prior treatment, laboratory values and other mandatory requirements appear in the eligibility criteria below.
- Where it takes place
- Switzerland
- Next step
- Save the trial, show it to the treating physician, and confirm current recruitment with the study center. Costs, documents and travel →
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Overview
The aim of this study is to evaluate whether a new test using mannitol infusion can diagnose the cause of polyuria-polydipsia syndrome as accurately as the current standard test (hypertonic saline infusion) and to compare which test patients prefer. The goal is to identify a simpler and more patient-friendly diagnostic approach.
Detailed description
Polyuria-polydipsia syndrome (PPS), characterized by excessive urination and fluid intake, can have different underlying causes, including a deficiency of the hormone vasopressin (AVP-D) or excessive fluid intake without AVP-D (primary polydipsia). Correctly identifying the cause is essential, as the treatments differ and an incorrect diagnosis can negatively impact patient care.
A blood marker called copeptin is used to support the diagnosis, as it reflects vasopressin levels in the body. Currently, the most accurate method involves measuring copeptin after stimulation with hypertonic saline. However, this test is complex, requires close medical monitoring, and can be uncomfortable for patients.
Mannitol is a substance already used in routine clinical care and may offer a simpler way to stimulate copeptin release. Early results suggest that it could provide similar diagnostic accuracy with fewer side effects and better patient comfort.
This study is a randomized, cross-over, multicenter trial in which participants undergo both tests (mannitol and hypertonic saline) in random order. The study compares the diagnostic accuracy and patient preference for both methods, as well as safety and tolerability. In addition, it explores whether other clinical and laboratory measures can further improve the diagnosis of PPS.
Interventions
- Diagnostic test Mannitol
Intravenous infusion of 1.5g/kg body weight (max. 120g) mannitol is given over 30 minutes (≙ 7.5ml/kg body weight). - Diagnostic test Hypertonic Saline
Intravenous infusion of NaCl 3% is given first as a bolus of 250ml over 15 minutes, then with an infusion rate of 0.15ml/kg body weight / minute (≙ 9ml/kg body weight/hour).
Primary outcome measures
- Overall Diagnostic Accuracy [Time frame: One time assessment at Follow up Visit 2 (10 weeks after baseline)]
- Patient Test Preference [Time frame: 1 week after completion of both diagnostic tests]
Secondary outcome measures (12)
- Diagnostic Performance Measures for AVP-D [Time frame: At completion of follow-up, 10 weeks after last diagnostic test]
- Diagnostic Performance Measures for PP [Time frame: At completion of follow-up, 10 weeks after last diagnostic test]
- Optimal copeptin cut-off after mannitol infusion [Time frame: At completion of follow-up, 10 weeks after last diagnostic test]
- Frequency and severity of clinical symptoms [Time frame: During each test day (baseline to end of monitoring period 90 minutes/ 240 minutes)]
- Subjective burden of each test assessed by numeric rating scale [Time frame: Immediately after each test day]
- Psychopathological assessment (STAI-T) [Time frame: Baseline]
- Autistic traits [Time frame: Baseline]
- Quality of Life in Posterior Pituitary Disease [Time frame: Baseline and follow-up (10 weeks )]
- Change in oxytocin/neurophysin I levels [Time frame: Baseline and 90 minutes post-stimulation]
- Spearman's rank correlation coefficient between psychopathology questionnaires and oxytocin levels [Time frame: Baseline and 90 minutes post-stimulation]
- Spearman's rank correlation coefficient between psychopathology questionnaire and neurophysin I levels [Time frame: Baseline and 90 minutes post-stimulation]
- Validation of clinical diagnostic score [Time frame: After test day 2 and 10 weeks thereafter]
Eligibility criteria
Inclusion criteria
- Age ≥ 18 years
- Hypotonic polyuria/polydipsia syndrome defined as polyuria >40ml/kg body weight/24h and polydipsia >3l/24h; and urine osmolality <800mOsm/L or known AVP-D based on accepted criteria
Exclusion criteria
- Polyuria/polydipsia secondary to diabetes mellitus, hypercalcemia, or hypokalemia
- Diagnosis of AVP-R (Copeptin > 21.4 pmol/L)
- Evidence of acute illness
- Epilepsy requiring treatment
- Uncontrolled arterial hypertension (blood pressure >160/100mmHg at baseline
- eGFR < 60 ml/min/1,73 m2
- Cardiac failure (NYHA III-IV)
- Diagnosis of liver cirrhosis, Child-Pugh Class C
- Uncorrected adrenal or thyroidal deficiency
- Pregnancy or breastfeeding
- Current or unresolved urinary obstruction
- Enrollment in a clinical trial within the last 30 days
- Patients refusing or unable to give written informed consent
- Inability to follow study procedures
Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.
Healthy volunteers: No
Study design
- Allocation
- Randomized
- Model
- Crossover
- Masking
- Open label
- Primary purpose
- Diagnostic
Study locations
Switzerland · 1 center
- University Hospital Basel — Basel
Identifiers
NCT: NCT07569861 · 2026-00480;kt25ChristCrain7