Primary Polydipsia

Definition: Excessive volitional water intake

Epidemiology:

 • 6-20% of patients with psychiatric disorders - Most commonly schizophrenia (10-20%)

 • Other associations: affective & anxiety disorders, anorexia nervosa, & developmental disabilities

 • Symptomatic hyponatremia occurs in only 2-5%

 • 70% of pts are tobacco users; in one study, all of those with symptomatic hyponatremia were heavy smokers

Primary Polydipsia Physiology"

 • Malfunction of hypothalamic thirst center

 • ADH suppression and Thirst set points are different - Thirst persists even with suppressed ADH

 • Suggested explanations:

    - Hippocampal neuroendocrine dysfunction

    - K+ deficits impairing urine concentrating abilities

    - Co-morbid diabetes insipidus

Differential Diagnosis: Diabetes Insipidus, Impaired Urinary Dilution, Pseudohyponatremia, SIADH, MDMA intoxication

Initial Workup: Serum Osm, Urine Osm, Serum Sodium, Urine Sodium



By @Alert_Oriented3



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