The Leeds Teaching Hospitals NHS Trust

Water Deprivation Test

The principle of the water deprivation test is to assess the ability of the patient to concentrate urine when fluids are withheld. Water deprivation should normally cause increased secretion of ADH, resulting in the production of small volumes of concentrated urine

Tube Plain Universal (Urine) / Serum Gel (Serum)
ID 39331
Availability Requester must contact the Duty Biochemist Ext 26922 (option 2) to confirm date of procedure. Failure to do this may result in a delay in the reporting of results.
Additional Information Primary polydipsia can cause a low urine osmolality and should be considered as a cause, particularly in psychiatric patients. Primary polydipsia will be associated with a dilutional hyponatraemia. With primary polydipsia, urine may remain dilute even with fluid restriction, but serum osmolality is often low or low to normal. A prolonged water deprivation test may be required. IMPORTANT: On the day of the water deprivation test, please contact the Duty Biochemist on ext 26922 (option 2). This will allow us to ensure sufficient staff resources are available for prompt analysis of osmolality. A urine osmolality >750 mOsmol/kg excludes diabetes insipidus (DI) as a cause of polyuria (in classic DI, serum osmolality rises above 300 mOsmol/kg and urine osmolality remains <350 mOsmol/kg). However, a low urine osmolality is NOT diagnostic of DI.
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Contact For further details please contact Leeds Pathology customer services:
Sample REQ Urine / Serum
Ref. Range Notes Blood Sciences Refernce ranges available through the useful information and links page:
Telepath OSMU1L / OSM1L