Use of Copeptin in Diabetes Insipidus

Use of Copeptin in the Differential Diagnosis of Diabetes insipidus-a Prospective International Study

Prospective evaluation of the novel biomarker copeptin in the differential diagnosis of diabetes insipidus against the standard diagnostic test methods.

Purpose of this study is to compare the overall diagnostic accuracy of the three following diagnostic test procedures in diabetes insipidus (central, nephrogenic) and primary polydipsia: a) classical water deprivation test alone, b) classical water deprivation test plus plasma copeptin cut-off levels, c) hypertonic saline infusion test plus plasma copeptin measurement.

The investigators hypothesize that firstly b) and c) is better as a). Secondly the investigators hypothesize that c) is non-inferior to b).

Inclusion Criteria:

• Polyuria or/and Polydipsia or/and therapy with synthetic adenovirus proteinase (AVP) derivate
• Urine osmolality <800mOsm/kgH20

Exclusion Criteria:

• Polyuria due to diabetes mellitus
• Hypokalemia
• Hyperkalemia (>5mmol/l)
• Hypercalcemia
• Kidney disease (min.: glomerular filtration rate (GFR) 60ml/min/1.73m2)
• Pregnancy
• Hyponatremia >135mmol/L
• Hypernatremia >145mmol/L
• Hypo- or hypervolemia
• uncorrected adrenal or thyroidal deficiency
• Cardia failure
• Epilepsia
• Uncontrolled hypertension