What is the role of a water deprivation test in the diagnosis of hypopituitarism (panhypopituitarism)?

Updated: Jun 09, 2020
  • Author: Bernard Corenblum, MD, FRCPC; Chief Editor: Romesh Khardori, MD, PhD, FACP  more...
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Answer

A water deprivation test can help to differentiate psychogenic polydipsia from diabetes insipidus and nephrogenic diabetes insipidus. Supervise patients constantly to inhibit water intake, as patients with psychogenic polydipsia often use any means possible to consume water (eg, drinking from a toilet bowl). While withholding water, take urine samples hourly to measure urine osmolalities, with serum osmolarity measured at the beginning and end.

If the cause is psychogenic, urine osmolality increases while serum osmolality remains normal. If urinary concentrations do not increase in a water deprivation test, despite the rise in serum osmolarity, the diagnosis of diabetes insipidus is established (central or nephrogenic).


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