Diagnosis and Management of Diabetes Insipidus

Clinical Presentation and Diagnosis

The American Thoracic Society suggests that a urine sodium of 39 mmol/L is not particularly helpful for diagnosing DI but doesn't exclude it 1
Patients with confirmed DI are at risk for life-threatening hypernatremic dehydration during any illness that impairs oral intake, and should avoid normal saline for IV rehydration as it can worsen hypernatremia, according to the National Kidney Foundation 2
The National Kidney Foundation recommends that patients with DI should carry a medical alert card explaining their diagnosis and emergency fluid management, and should use 5% dextrose in water as the preferred IV fluid 3

The American College of Chest Physicians states that SIADH would show low serum osmolality (<275 mOsm/kg), inappropriately high urine osmolality (>500 mOsm/kg), and hyponatremia (serum sodium <134 mmol/L), which is the opposite pattern of DI 1