How Is Psychogenic Polydipsia Diagnosis?

Diagnostic tests for primary polydipsia usually involves the fluid deprivation test to exclude ADH problems. The desmopressin test is also used, in which the synthetic hormone is used as a diagnostic workup to test for inappropriate secretion of vasopressin, as seen in DI and SIADH.

How is psychogenic polydipsia diagnosed?

The main differential diagnosis for primary polydipsia is diabetes insipidus (DI). The diagnostic method that has been used for a long time is the indirect water deprivation test (WDT), which is an indirect measurement of the arginine vasopressin (AVP) activity, combined with the administration of desmopressin.

How can you tell the difference between psychogenic polydipsia and diabetes insipidus?

In primary polydipsia, urine osmolality increases with water restriction so that urine-to-plasma osmolality exceeds 1.0. In diabetes insipidus, urine osmolality remains inappropriately low, with a urine-to-plasma osmolality <1.0.