Indications directory

Exclusion diagnostics:

Measurement of urine volume and fluid intake in a 24-hour period with evaluation of osmolality and sodium-concentration in the serum two times over. Diuretics and antidiuretics should be discontinued, and diabetes mellitus ruled out beforehand.

If urine excretion exceeds 2,5 l in a 24-hour period, a fluid deprivation test is recommended. In the first stage there is a 12-hour fluid deprivation phase with measurements of serum- and urine-osmolality as well as ADH.

Alternatively:

Evaluation of the osmolality in the first morning urine after a fluid deprivation period from 2000 hrs the previous day. There should also be a blood extraction for osmolality-evaluation (serum) before 0800 hours in the morning. If osmolality levels in the morning urine are above 800 mOsm/kg and below 295 mOsmol/kg in the serum, then diabetes insipidus is very unlikely. If morning urine osmolality is below 800 mOsm/kg, an inpatient fluid deprivation test with subsequent Desmopressin-administration (DDAVP) (Minirin) is recommended for further evaluation (please refer to function tests).

Please also refer to section “hypernatremia”