# Intraoperative Diagnosis and Management of Arginine Vasopressin Disorder During Pituitary Tumor Resection via Transsphenoidal Endoscopic Navigation

## TL;DR

A patient developed a hormone disorder during brain tumor surgery, requiring urgent treatment to manage fluid and electrolyte balance.

## Contribution

Demonstrates the importance of intraoperative monitoring for diagnosing and managing arginine vasopressin disorders during pituitary surgery.

## Key findings

- Acute polyuria and hyperosmolality indicated an arginine vasopressin disorder during surgery.
- Desmopressin and fluid therapy effectively corrected fluid and electrolyte imbalances.
- Postoperative monitoring was crucial for managing persistent symptoms and preventing complications.

## Abstract

Arginine vasopressin (AVP) disorders (previously called diabetes insipidus) lead to excessive urination due to reduced antidiuretic hormone (ADH) secretion or kidney resistance to ADH. This results in decreased water reabsorption, causing dehydration and electrolyte imbalances. Diagnosing these disorders during general anesthesia is challenging, but close monitoring of electrolytes and urine output, especially during high-risk surgeries such as intracranial procedures, is crucial.

A 64-year-old woman with a history of asthma presented with severe bifrontal headaches and left-eye medial gaze palsy. Imaging showed a large sellar mass extending into the sphenoid sinus, requiring a transsphenoidal resection. An hour and 30 minutes into surgery, the patient developed acute polyuria (1 L urine), hyperosmolality (Na: 149 mmol/L), and colorless urine with low specific gravity (1.003), indicating an arginine vasopressin disorder. Desmopressin (DDAVP) was administered, improving urine specific gravity to 1.013, and a D5W infusion corrected a 2.5 L fluid deficit. Severe hypokalemia (K: 2.6 mmol/L) and hyperglycemia (glucose: 230 mg/dL) were also treated, with electrolyte and glucose levels stabilizing postoperatively. On postoperative day (POD) 2, the patient experienced polyuria up to 23 L and excessive thirst, requiring additional desmopressin on POD 3. She was discharged on POD 9. Arginine vasopressin disorders, especially vasopressin deficiency (central diabetes insipidus), commonly result from neurohypophyseal damage during cranial surgery. Prompt diagnosis and treatment with desmopressin and fluids can effectively manage fluid and electrolyte imbalances, preventing severe complications such as hypernatremia and neurological deficits. This case highlights the importance of intraoperative urine and laboratory monitoring to ensure timely recognition and management.