Psychogenic Polydipsia in a Patient With a Clinical Triad

Psychogenic Polydipsia (PP) is a condition involving excessive fluid intake causing hyponatremia. While the mechanism is unknown, treating arginine vasopressin (AVP) dysregulation with the class of drugs, vaptans, during acute psychotic episodes has been an effective treatment. These patients may present with a triad of acute psychosis, polydipsia, and electrolyte imbalances suggesting a syndrome of inappropriate antidiuretic hormone. Our patient is a 57-year-old female with a past medical history of schizophrenia who presented with seizures due to severe hyponatremia in the context of excessive water consumption and mild delusions regarding her sister. Her episodes of neural dysfunction started after she stopped taking her antipsychotic medications, making a drug-induced syndrome of inappropriate antidiuretic hormone secretion (SIADH) less likely. However, she had a normal urine osmolality raising suspicion of antidiuretic hormone involvement. The mechanism of hyponatremia in the context of polydipsic schizophrenia is not well established. Some evidence suggests that brain changes may cause AVP dysregulation, which can be exacerbated by acute psychotic episodes. Our case report describes a clinical scenario with the clinical triad of acute psychosis, polydipsia, and electrolyte imbalances suggestive of this mechanism.