A Water Deprivation Test (WDT) is a lengthy Endocrine procedure to diagnose Arginine Vasopressin Deficiency (AVP-D). The test requires strict supervision for patient safety, due to the risk of severe dehydration, and to ensure there is no tampering of the samples or water drinking by the patient.
From midnight patients are required to abstain from all fluids, complete a fluid balance chart, collect and measure urine samples. The following day, overnight samples are sent to pathology, with weight, urine and blood samples collected hourly. Results for Urine Osmolality (Osm), Plasma Sodium and Plasma Osm are assessed to determine the need to continue testing or discharge the patient.
An illustrative case high lightening the importance of strict patient supervision during the WDT is presented below.
A 30yr old female referred to the St Vincent’s Hospital, Endocrine Testing Area (ETA) for a repeat WDT due to inconsistent results in New Zealand. The patient travelled 4hrs to St Vincent’s the day prior to collect necessary equipment for the test and baseline weight.