Copeptin Measurement After Mannitol and Hypertonic Saline for the Diagnosis of Polyuria-polydipsia Syndrome

NCT07569861 | Not Yet Recruiting

• 1 other identifier: 2026-00480;kt25ChristCrain7
• Study Type: interventional
• Target: 144
• Locations: 1 country
• Sites: 1

Brief Summary

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.

Conditions

Arginine Vasopressin Deficiency; Primary Polydipsia

Keywords

Copeptin Measurement; Diagnosis of Polyuria-polydipsia syndrome; Mannitol; Hypertonic Saline Infusion

Outcome Measures

Primary Outcomes (2)

• Overall Diagnostic Accuracy

  The overall diagnostic accuracy is defined as the proportion of correct diagnoses out of all diagnoses based on the stimulated copeptin value. Final diagnosis will be made after termination of the study by two endocrine specialists who will be blinded to the copeptin results of the mannitol infusion.

  One time assessment at Follow up Visit 2 (10 weeks after baseline)

• Patient Test Preference

  Patient-reported preference between mannitol infusion and hypertonic saline infusion, assessed using a 5-point Likert scale ranging from -2 (strong preference for hypertonic saline) to +2 (strong preference for mannitol).

  1 week after completion of both diagnostic tests

Secondary Outcomes (16)

• Diagnostic Performance Measures for AVP-D

  At completion of follow-up, 10 weeks after last diagnostic test

• Diagnostic Performance Measures for PP

  At completion of follow-up, 10 weeks after last diagnostic test

• Optimal copeptin cut-off after mannitol infusion

  At completion of follow-up, 10 weeks after last diagnostic test

• Frequency and severity of clinical symptoms

  During each test day (baseline to end of monitoring period 90 minutes/ 240 minutes)

• Subjective burden of each test assessed by numeric rating scale

  Immediately after each test day

Study Arms (2)

Mannitol Infusion

EXPERIMENTAL

Diagnostic evaluation of polyuria polydipsia syndrome through copeptin measurement after mannitol infusion.

Diagnostic Test: Mannitol

Hypertonic Saline Infusion (HIS)

ACTIVE COMPARATOR

Diagnostic evaluation of polyuria polydipsia syndrome through copeptin measurement after HIS

Diagnostic Test: Hypertonic Saline

Interventions

Mannitol DIAGNOSTIC_TEST

Intravenous infusion of 1.5g/kg body weight (max. 120g) mannitol is given over 30 minutes (≙ 7.5ml/kg body weight).

Mannitol Infusion

Hypertonic Saline DIAGNOSTIC_TEST

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).

Hypertonic Saline Infusion (HIS)

Eligibility Criteria

• Age: 18 Years+
• Sex: all
• Healthy Volunteers: No
• Age Groups: Adult (18-64), Older Adult (65+)

You may qualify if:

• 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

You may not qualify if:

• 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

Sponsors & Collaborators

• University Hospital, Basel, Switzerland: lead

Study Sites (1)

University Hospital Basel

Basel, 4031, Switzerland

Location

MeSH Terms

Conditions

Diabetes Insipidus, Neurogenic; Polydipsia, Psychogenic; Diabetes Insipidus

Condition Hierarchy (Ancestors)

Kidney Diseases; Urologic Diseases; Female Urogenital Diseases; Female Urogenital Diseases and Pregnancy Complications; Urogenital Diseases; Male Urogenital Diseases; Pituitary Diseases; Endocrine System Diseases; Polydipsia; Pathologic Processes; Pathological Conditions, Signs and Symptoms; Signs and Symptoms; Behavioral Symptoms; Behavior

Study Officials

• Mirjam Christ-Crain, Prof. Dr.

  University Hospital of Basel

  STUDY CHAIR

Central Study Contacts

Talitha Hildebrandt

CONTACT

+41 61 55 65075; talithanatalja.hildebrandt@usb.ch

Cemile Bathelt

CONTACT

+41 61 55 65407; cemile.bathelt@usb.ch

Study Design

• Study Type: interventional
• Phase: not applicable
• Allocation: RANDOMIZED
• Masking: NONE
• Purpose: DIAGNOSTIC
• Intervention Model: CROSSOVER
• Sponsor Type: OTHER
• Responsible Party: SPONSOR

Model Details: Randomized open-label cross-over diagnostic multicenter study

Study Record Dates

• First Submitted: March 30, 2026
• First Posted: May 6, 2026
• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): June 1, 2030
• Study Completion (Estimated): June 1, 2030
• Last Updated: May 6, 2026

Record last verified: 2026-05

Locations

CH (1)