The objective of this study is to find out what the pharmacokinetic/dynamic (PK/PD) characteristics of desmopressin melt are in nocturia patients (compared to healthy volunteers and children). The main questions the investigators want to answer are:

• Are differences related to the pathophysiological factors involved in nocturia?
• Are there age/gender/size differences?
• Can the investigators identify patients who are likely to develop hyponatraemia?
• Can the investigators individualize treatment and reduce risk for hyponatraemia?

Day 1:

• Patient is being hospitalized in the morning
• General anamnesis and clinical examination
• Uroflow and residue measurements (3x)
• Sober blood sample, to determine plasma concentrations of Na+, Cl-, osmolality and creatinin

Day 1-2:

- In the evening at 20h:

• start (with empty bladder!) 24h miction-incontinence-residue registration: urine collections every 3 hours (every portion of urine within a period of 3 hours must be collected in the same collection device), with: registration of volumes and measurement urinary concentrations of Na+, Cl-, osmolality and creatinin
• Measurement of blood pressure during 24h

Day 2-3:

• In the evening at 19h (day 2): drink 15mL/kg water

• At 20h: take desmopressin melt 120µg + start:

  • 24h miction-incontinence-residue registration: registration of volumes and measurement urinary concentrations of Na+, Cl-, osmolality and creatinin (U1-U7)
  • Measurement of blood pressure during 24h
  • Collection of urine:U1 at 19h, U2 at 20h, together with intake of first desmopressin melt, U3 at 21h = 1h after desmopressin melt intake, U4 at 22h = 2 after desmopressin melt intake,U5 at 23h = 3h after desmopressin melt intake, U6 at 2h (day 3) = 6h after desmopressin melt intake, U7 at 8h = 12h after desmopressin melt intake
  • Blood samples for blood levels of desmopressin: 1h, 2h, 3h, 6h after desmopressin melt intake, 12h after desmopressin melt intake + plasma concentrations of Na+, Cl-, osmolality and creatinin (safety profile)
  • At 8h in the morning (day 3): drink 15mL/kg water + collection of urine per hour during 3h with measurement of urinary concentrations of Na+, Cl-, osmolality and creatinin: U8 at 9h, U9 at 10h, U10 at 11h

• Patient can go home on day 3, unless he is at high risk for side effects, high-risk patients are hospitalized for 7 days

Inclusion Criteria:

• written informed consent prior to the performance of any study-related activity
• patients, men and woman, 18 years and older, with nocturnal polyuria, resulting in nocturia (2 voids or more at night) and/or nocturnal incontinence.

Exclusion Criteria:

• hypersensitivity/anaphylactic reaction on desmopressin or one of the other substances
• pregnancy
• genitourinary tract pathology (infection, tumor,...)
• urolithiasis
• suspicion or evidence of cardiac failure
• moderate to severe renal insufficiency (creatinin clearance < 50 ml/min)
• psychogenic or habitual polydipsia
• hyponatraemia or predisposition for hyponatraemia
• diabetes insipidus
• syndrome of inadequate ADH production