Plasma Copeptin in Response to Oral Urea in Healthy Adults and Patients With Polyuria-polydipsia Syndrome

Plasma Copeptin in Response to Oral Urea in Healthy Adults and Patients With Polyuria-polydipsia Syndrome: a Double-blind, Randomized, Placebo-controlled Cross-over Proof-of-concept and Pilot Study - The URANOS Study

The aim of this study is to investigate whether oral urea stimulates copeptin release and, if so, whether it may provide a novel diagnostic test in the differentiation between AVP-D (Arginine vasopressin deficiency) and PP (primary polydipsia).

This study consists of two parts, including healthy adults (study part 1 - proof of concept) and adults with an established diagnosis of PP or AVP-D (study part 2 - pilot study).

If the results of study part 1 suggest that oral urea is a potent stimulator of copeptin in healthy adults, study part 2 will be conducted, meaning that adults with an established diagnosis of PP or AVP-D will be included. If study part 1 demonstrates no relevant copeptin increase in response to oral urea, the study will be terminated thereafter and study part 2 will not be conducted.

Healthy volunteers

Inclusion Criteria:

• Age ≥18 years
• Healthy with no medication except hormonal contraception

Exclusion Criteria:

• Participation in a trial with investigational drugs within 30 days
• Evidence of disordered drinking habits and diuresis defined as polyuria >50ml/kg body weight/24h and polydipsia >3l /24h
• Known allergy towards components of the study drink
• Pregnancy and breastfeeding
• Intention to become pregnant during the study
• Evidence of acute illness

Patients

Inclusion Criteria:

• Age ≥ 18 years
• Documented PP or AVP-D based on accepted diagnostic criteria, i.e., water deprivation test, hypertonic saline infusion test or arginine infusion test. Accordingly, patients must have evidence of disordered drinking habits and diuresis defined as polyuria >50ml/kg body weight/24h and polydipsia >3l /24h or must be on regular daily desmopressin medication

Exclusion Criteria:

• Participation in a trial with investigational drugs within 30 days
• Known allergy towards components of the study drink
• Pregnancy and breastfeeding
• Evidence of acute illness