How to treat a patient with suspected diabetes insipidus (DI) due to traumatic brain injury (TBI) presenting with polyuria, hypernatremia, and hypotension, and what isotonic fluids can be used to manage hypernatremia?

From the Guidelines

For a patient with suspected diabetes insipidus (DI) following traumatic brain injury who has high urine output, hypernatremia, and hypotension, I recommend immediate treatment with a two-pronged approach, starting with isotonic fluids such as 0.9% normal saline to restore blood pressure and intravascular volume, as recommended by the international multidisciplinary perioperative quality initiative 1.

Initial Management

• Address the volume depletion with isotonic fluids such as 0.9% normal saline to restore blood pressure and intravascular volume.
• This approach is supported by the evidence-based consensus recommendations from the international multidisciplinary perioperative quality initiative, which suggests the use of buffered crystalloid solutions in the absence of hypochloraemia, with a probable exception being the setting of TBI, where 0.9% saline is recommended 1.

Hypernatremia Management

• Once hemodynamic stability is achieved, address the hypernatremia with hypotonic fluids like 0.45% saline or D5W (5% dextrose in water), as suggested by the international expert consensus statement on the diagnosis and management of congenital nephrogenic diabetes insipidus 1.
• D5W is appropriate for treating hypernatremia once the patient is hemodynamically stable, as it provides free water to help lower serum sodium levels gradually.

Diabetes Insipidus Management

• For the DI itself, administer desmopressin (DDAVP) at an initial dose of 1-2 mcg IV or 10-20 mcg intranasally.
• Monitor urine output, serum sodium, and urine osmolality closely, adjusting fluid therapy and desmopressin dosing accordingly.
• The goal is to reduce sodium by no more than 8-10 mEq/L per 24 hours to avoid cerebral edema from rapid osmotic shifts, as careful fluid management is essential in these patients who can quickly shift between DI and syndrome of inappropriate antidiuretic hormone secretion (SIADH) following TBI 1.

Key Considerations

• Avoid the use of albumin in patients with traumatic brain injury, as recommended by the international multidisciplinary perioperative quality initiative 1.
• Avoid the use of synthetic colloids, as they have been associated with adverse effects in critically ill patients 1.
• Maintain normal blood volume, optimize cerebral blood flow, and avoid reduction in plasma osmolarity, as the primary goal for fluid therapy during neurosurgery 1.

From the FDA Drug Label

Desmopressin Acetate Injection is indicated as antidiuretic replacement therapy in the management of central (cranial) diabetes insipidus and for the management of the temporary polyuria and polydipsia following head trauma or surgery in the pituitary region Prior to treatment with desmopressin acetate injection, assess serum sodium, urine volume and osmolality. Ensure that serum sodium is normal prior to initiating or resuming treatment with desmopressin acetate injection. Limit fluid intake to a minimum from 1 hour before administration until 8 hours after administration.

To treat a patient with suspected diabetes insipidus (DI) due to traumatic brain injury (TBI) presenting with polyuria, hypernatremia, and hypotension, desmopressin acetate injection can be used as antidiuretic replacement therapy.

• Assess serum sodium, urine volume, and osmolality before starting treatment.
• Ensure normal serum sodium levels before initiating treatment.
• Restrict fluid intake to a minimum from 1 hour before administration until 8 hours after administration.
• Monitor serum sodium within 1 week and approximately 1 month of initiating desmopressin acetate, and periodically thereafter. For managing hypernatremia, isotonic fluids such as 0.9% Sodium Chloride Injection, USP can be used.
• The volume of diluent is weight-based, with 10 mL for patients weighing 10 kg or less and 50 mL for patients weighing more than 10 kg.
• Monitor blood pressure and pulse during infusion 2.

From the Research

Treatment of Diabetes Insipidus (DI) due to Traumatic Brain Injury (TBI)

• The treatment of DI due to TBI involves careful monitoring of fluid balance and hormonal replacement 3.
• Desmopressin, an arginine-vasopressin (AVP) analog, is the primary treatment for central DI 4.
• In the absence of desmopressin, alternative options such as thiazides, carbamazepine, and chlorpropazine can be used to manage central DI 4.
• Vasopressin can also be used to treat central DI, but it has a shorter duration of action compared to desmopressin 5.

Management of Hypernatremia

• Hypernatremia in patients with DI due to TBI can be managed with isotonic fluids such as sodium chloride solution 6.
• The goal of fluid management is to correct hypernatremia and prevent dehydration 3.
• Isotonic fluids can help to replace lost sodium and water, and to maintain fluid balance 6.
• In some cases, cortisone acetate may be administered in combination with vasopressin to manage hypernatremia and polyuria 6.

Monitoring and Complications

• Patients with DI due to TBI require close monitoring of fluid balance, electrolyte levels, and urine output 3.
• Complications such as water intoxication and hyponatremia can occur with desmopressin therapy, and careful dose titration and monitoring of serum osmolality are necessary to minimize these risks 5.
• Early recognition and management of hypernatremia and dehydration are critical to prevent life-threatening complications 4, 6.