Abstract: FR-PO0606
Triphasic Diabetes Insipidus: A Challenging Case of Severe Syndrome of Inappropriate Antidiuretic Hormone Secretion After Traumatic Brain Injury
Session Information
- Fluid, Electrolyte, and Acid-Base Disorders: Clinical - 2
November 07, 2025 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Fluid, Electrolytes, and Acid-Base Disorders
- 1102 Fluid, Electrolyte, and Acid-Base Disorders: Clinical
Authors
- Faldu, Czarina Teano, UVA Health, Charlottesville, Virginia, United States
- D'Silva, Susanna, University of Virginia, Charlottesville, Virginia, United States
- Nasuti, Geoffrey, UVA Health, Charlottesville, Virginia, United States
- Okusa, Mark D., UVA Health, Charlottesville, Virginia, United States
- Chopra, Tushar, UVA Health, Charlottesville, Virginia, United States
Introduction
Central diabetes insipidus (CDI) is a known complication of traumatic brain injuries (TBI) which can result in severe cases of hypernatremia. Triphasic DI is a rare entity with an incidence of only 1.1%. The first phase is characterized by DI which then transforms into a syndrome of inappropriate antidiuretic hormone (SIADH) with the third phase resorting back to DI. We present a challenging case of severe SIADH with a urine osmolality above 1200 mOsm/kg.
Case Description
A 26-year-old female presents after a TBI from a motor vehicle crash. She developed hypernatremia to 156 mmol/L on Day 2, with a urine osmolality of 112 mOsm/kg and 4,210 cc of urine in 24 hours. She was initiated on desmopressin (DDAVP) 1 mcg twice daily with the improvement of sodium to normonatremia. Sodium levels began to decline on Day 6 with a urine osmolality of 1,188 mOsm/kg. DDAVP was held, hypertonic saline and furosemide were given, which resulted in improvement of sodium. Day 9, urine output increased, reaching 11,975 mL in 24 hours with a urine osmolality of 78 mOsm/kg on Day 10. Hypertonic saline and furosemide were stopped and DDAVP was restarted at 1 mcg IV twice daily along with a D5W fluid rate to match urine output. On Day 12, the patient was noted to have a urine osmolality of 1219 mOsm/kg – the same day she underwent a cranioplasty. DDAVP was reduced to 0.5 mcg IV twice daily, which was later switched to po formulation and was discharged on the same regimen of 50 mcg po twice a day.
Discussion
Management of DI involves critical attention to urine and serum osmolalities along with accurate measurement of intake and outputs. The unpredictability of the development of triphasic DI can result in rapid life-threatening fluctuations in water balance. This case exemplifies the dynamic changes that can occur within hours, prompting careful monitoring of lab values and symptoms from all members of the multidisciplinary team.
Urine osmolality and serum sodium during hospitalization.