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Abstract: SA-PO742

Unusual Polydipsia-Polyuria Syndrome, Hypernatremia, and Hypercopeptinemia: What Is the Diagnosis?

Session Information

Category: Fluid, Electrolytes, and Acid-Base Disorders

  • 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical


  • Henry, Aaron, University of Vermont Larner College of Medicine, Burlington, Vermont, United States
  • Mann-Gow, Travis, University of Vermont Larner College of Medicine, Burlington, Vermont, United States
  • Agbasi, Nneoma, University of Vermont Medical Center, Burlington, Vermont, United States
  • Jeremiah, Chidiebube, East Tennessee State University, Johnson City, Tennessee, United States
  • Onuigbo, Macaulay A., University of Vermont Larner College of Medicine, Burlington, Vermont, United States

Polydipsia-Polyuria Syndrome (PPS) can represent central diabetes insipidus (DI), nephrogenic DI or primary polydipsia (PP). Correct differentiation is crucial; Copeptin assay is useful. We describe PPS, hypernatremia, and hypercopeptinemia: Is this a new syndrome?

Case Description

A 76-yo female with Alzheimers disease was evaluated for dizziness, fatigue, incessant thirst, and chest pain. She was drinking excessively even from public faucets and had increased very wet diapers. The daughter restricted water intake at home. Vitals signs were stable. Physical examination was unremarkable. Sodium was 158 mmol/L, BUN 178 mg/dL, creatinine higher at 1.46 mg/dL, BNP 2000 pg/mL. Chest radiograph and non-contrast head CT were non-diagnostic. She received IV D5W and drank to thirst. Sodium normalized (Figure A). BUN trajectory was a near mirror image of Na trajectory (B). Incessant thirst persisted. Copeptin was 79.7 (<13.1) pmol/L. She was discharged with a diagnosis of PP and a Psychiatry referral.


Does our patient have partial nephrogenic DI from AKI, drug-induced SIADH (?Sertraline), and/or PP, or a combination thereof? Hypernatremia on admission probably reflected true water deficit following forced restriction of water intake at home by the daughter in the few days preceding the admission. Follow up would require a delicate balance of controlled water intake. Psychiatry management of suspected PP could include behavioral therapy, health education, relaxation techniques and positive reinforcement. Her dementia could be a barrier. Recent evidence supports a role for GLP-1 agonists in PP. Several unanswered diagnostic and therapeutic questions around PPS remain and call for further research.

Na and BUN trajectories