Learning objectives

• Describe diabetes insipidus
• Recognize the symptoms and signs of diabetes insipidus
• Anesthetic management of a patient with diabetes insipidus

Definition and mechanisms

• Diabetes insipidus (DI) is a disorder of urinary concentration caused by a temporary or chronic deficiency of or insensitivity to antidiuretic hormone (ADH) or vasopressin
• The condition renders the kidneys unable to effectively autoregulate water balance, resulting in polyuria, polydipsia, and electrolyte abnormalities (e.g., hypernatremia, hypokalemia)

Classification

• Central DI or ADH deficiency: Reduced ADP secretion due to damage to the pituitary gland or hypothalamus or genetics
• Nephrogenic DI or ADH resistance: Normal ADP secretion, but the kidneys are unable to properly respond to ADH due to an inherited genetic disorder or chronic kidney disorder
• Gestational DI: A very rare condition that occurs during pregnancy when an enzyme made by the placenta destroys ADH
• Primary polydipsia (dipsogenic DI): Damage to the hypothalamic thirst center causes excessive fluid intake leading to polyuria

Signs and symptoms

Clinical findings

• If the thirst mechanism is intact: Hydronephrosis and distended bladder due to excessive urinary volume
• If there is no access to free water or damage to the hypothalamic thirst center: Hypernatremia, dehydration, hypertonic encephalopathy, obtundation, coma, seizure, subarachnoid hemorrhage, and intracerebral hemorrhage

Complications

Dehydration, which may cause:

• Dry mouth
• Changes in skin elasticity
• Thirst
• Fatigue

Electrolyte imbalance, resulting in:

• Weakness
• Nausea
• Vomiting
• Loss of appetite
• Muscle cramps
• Confusion

Pathophysiology

Treatment

There is no cure → treatments aim to relieve thirst, decrease urine output, and prevent dehydration

• Central and gestational DI: Desmopressin (DDAVP) 
• Nephrogenic DI: Treat the underlying cause or use a thiazide, aspirin, or ibuprofen
• Primary polydipsia: Decrease fluid intake

Management

• Hypernatremia: ↑ MAC requirements
• Treat hypernatremia by estimating water deficit and replacing it with free water: 
  • Water deficit = total body water x (Serum Na [   ]/140-1)
• Volume depletion: Resuscitate with normal saline initially
• Central DI: DDAVP 1-2 mcg i.v. BID
• Nephrogenic DI: Hydrochlorothiazide/amiloride

Keep in mind

• Avoid rapid overcorrection if chronic hypernatremia (goal = <10 mEq/day)
• Be careful of cerebral edema, water intoxication, and volume overload

Suggested reading

• Mutter CM, Smith T, Menze O, Zakharia M, Nguyen H. Diabetes Insipidus: Pathogenesis, Diagnosis, and Clinical Management. Cureus. 2021;13(2):e13523. 
• Dharshan AC, Kohli-Seth R. Chapter 117. Diabetes Insipidus. In: Atchabahian A, Gupta R. eds. The Anesthesia Guide. McGraw Hill; 2013. Accessed January 17, 2023.