Diabetes Insipidus

Description

Diabetes insipidus (DI) describes a disease process defined by polyuria and polydipsia resulting from either:
- Decreased or absent secretion of antidiuretic hormone (ADH)
- Resistance to the action of ADH at the level of the kidneys
There are multiple etiologies:
- Neurogenic
- Nephrogenic
- Dipsogenic
- Gestational

Epidemiology

Incidence

Occurs during the postoperative course in ~30% of pituitary surgeries, although the course is usually transient
Overall incidence is difficult to obtain due to the various etiologies of DI.

Prevalence

1 in 25,000
Equal prevalence in males and females

Morbidity

Severe dehydration resulting in hypernatremia
Fever and cardiovascular collapse can occur in patients with coexisting illnesses, the elderly, or children.

Mortality

Rare, especially in adults without coexisting illness. However, may occur if treatment is delayed in children or the elderly in which the disease progresses to complete cardiovascular collapse.

Etiology/Risk Factors

Neurogenic: Decreased production of ADH by the hypothalamus in the brain. Risk factors include:
- Trauma
- Tumor in the region of the pituitary or hypothalamus
- Surgery in the region of the pituitary or hypothalamus
Nephrogenic: Decreased sensitivity to ADH by the kidneys. The most common cause in children is hereditary; 90% are associated with mutations in the AVPR2 gene that encodes for a dysfunctional vasopressin receptor (V2R). In adults, acquired nephrogenic DI is usually secondary to medications such as lithium, foscarnet, cidofovir, amphotericin B, demeclocycline, as well as a result of chronic hypercalcemia and hyperkalemia.
Dipsogenic: Defect in the thirst trigger (located in the hypothalamus) which causes increased thirst and fluid intake that subsequently suppresses vasopressin secretion and increases urine output.
Gestational: During pregnancy, all women produce vasopressinase by the placenta, which breaks down ADH. When excess vasopressinase is produced, gestational DI will occur. This etiology is the most common and can be treated by desmopressin.
- In a small subset of patients, the thirst mechanism is disrupted, causing DI; it is not improved with desmopressin.
- DI is also associated with other diseases of pregnancy, such as preeclampsia and HELLP syndrome. In these disease processes, hepatic vasopressinase is activated, and the only treatment is delivery of the fetus.

Physiology/Pathophysiology

Hypothalamus: Produces ADH in the supraoptic and paraventricular nuclei. ADH is then transported to the posterior lobe of the pituitary gland where it is stored for later use. It is released when the body senses that electrolyte and/or fluid status are unbalanced.
Kidney: The primary target for ADH and water retention; the hormone acts on the collecting ducts and distal convoluted tubules (DCT) to allow more water to be reabsorbed into the systemic circulation and therefore create a more concentrated urine.
Thirst sensation: Also regulated by the hypothalamus when it senses decreases in serum osmolarity.
In DI, either ADH secretion is deficient or the renal response to ADH is abnormal. This results in the following pathology:
- Increased urine output; water remains in the urine (polyuria)
- Decreased body water (dehydration)
- Increased serum [Na⁺]
- Increased serum osmolality
- Decreased urine osmolality or specific gravity
- Decreased urine [Na⁺]
- No change in total body sodium
- No change in urine sodium excretion

Anesthetic GOALS/GUIDING Principles

The possibility of DI should be evaluated in patients who present perioperatively with hypernatremia or excessive urine output; in particular, those who have had traumatic injury, tumor, status post surgery in the region of the pituitary or hypothalamus, or are pregnant.
In patients with known DI, electrolyte abnormalities may be present perioperatively. It is important to have recent chemistry labs done prior to anesthesia. Treatment may need to be administered perioperatively by the anesthetist.

Symptoms

Polyuria (4–18 L/day) with acute onset, usually within 24–48 hours of neurosurgery
Polydipsia, often with a craving for cold fluids
Hypovolemia: Depending on whether thirst mechanism is intact
Nocturia, enuresis in children, anorexia, fatigue

History

Central DI usually presents abruptly in patients with pituitary/hypothalamic surgery, head trauma, or malignancy.
Familial nephrogenic DI presents in early childhood.
Psychogenic polydipsia may have a long history.

Signs/Physical Exam

Minimal typically
Dehydration
In rare cases, there may be bladder enlargement

Treatment History

When patients are awake, they can usually drink enough fluids to replace their urine losses. Patients with inadequate thirst, however, may be treated with dextrose and water or IV fluid that is hypoosmolar with respect to the patient's serum. Serum sodium should not be reduced too quickly, ideally only 0.5 mEq/L/hr.

Medications

ADH therapy: Desmopressin (DDAVP) is a synthetic analog to endogenous vasopressin but with greater platelet and antidiuretic effects and decreased blood pressure effects. It binds to V₂ receptors in the renal collecting duct, causing increased water reabsorption in the kidney (increased urine osmolality, decreased urine output, and no effect on sodium, potassium, or creatinine reabsorption.
- Intravenous: 1–2 mcg BID, onset 15–50 minutes
- Oral: 0.05 mg BID, onset 60 minutes
- Nasal: 5–40 mcg BID
- The duration of action is highly variable and lasts from 5 to 21 hours. Additionally, it is renally excreted; thus, renal failure will prolong its action and dosage adjustments should be considered.

Diagnostic Tests & Interpretation

Labs/Studies

Urine specific gravity <1.005
Urine osmolality <200 mOsm/L
Serum [Na⁺] >145 mEq/L
A trial with desmopressin is used to distinguish between neurogenic and nephrogenic causes. If desmopressin reduces urine output and increases osmolarity, the pituitary production of ADH is deficient, and the kidney is normal. If the DI is due to renal pathology, desmopressin does not change either urine output or osmolarity.
MRI technology is being explored as a diagnostic tool.

Circumstances to delay/Conditions

Electrolyte abnormalities and dehydration may require optimization prior to surgery.

Classifications

Neurogenic
Nephrogenic
Dipsogenic
Gestational

PREOPERATIVE PREPARATION

Premedications

Consider administration of DDAVP either nasally or intravenously, if the clinical condition dictates.

INTRAOPERATIVE CARE

Choice of Anesthesia

No specific anesthetic choices are indicated aside from usual neuroanesthesia care and concerns.

Monitors

ASA monitors
Additional monitoring should be based upon the patient disease and procedure requirements. An arterial line (or central line) allows for serial monitoring of serum sodium and osmolality.
Foley catheter allows for accurate recording of fluid intake and output, and avoids overdistension of the bladder. Also allows for serial monitoring of urine sodium and specific gravity.

Induction/Airway Management

Usual neuroanesthesia induction

Maintenance

Usual neuroanesthesia maintenance and concerns
Fluids:
- Monitor ins and outs.
- Hypotonic IV fluids (hypoosmolar relative to the patient's serum) should be used to match the urine output.
- If using dextrose and water as fluid replacement, care must be taken to avoid hyperglycemia; generally, administration should be limited to 500–750 mL/hr and glucose levels should be monitored.
- When mannitol or furosemide must be administered to facilitate surgical conditions, it may confuse the picture with respect to fluid losses and replacement. Close monitoring of electrolytes, glucose, and serum osmolality as well as hemodynamic values should be used to aid in fluid replacement, as urine specific gravity may be misleading.
ADH therapy:
- Desmopressin 1–2 mcg/kg IV or SQ may be started or continued perioperatively.
- Re-dose if urine output remains >200–250 mL/hr for 2 hours with a urine specific gravity <1.005 or urine osmolality <200 mOsm/L.
Consider concomitant anterior pituitary insufficiency and the need for stress dose corticosteroids.

Extubation/Emergence

Usual neuroanesthesia concerns

Bed Acuity

The patient will need a monitored setting to allow for frequent lab checks and possible administration of DDAVP.

Medications/Lab Studies/Consults

DDAVP
Careful measurement of I/Os, monitor for hypovolemia, especially if the patient is unable to drink fluids freely
Serial serum/urine sodium levels and serum/urine osmolality levels
Endocrinology and neurology consults

Complications

If left untreated, may cause severe hypernatremia and the sequelae associated with this derangement

Nemergut EC , Dumond AS , Barry UT , et al. Perioperative management of patients undergoing transsphenoidal pituitary surgery. Anesth Analg. 2005;101:1170–1181.
NIH. Diabetes insipidus. Publication No. 01-4620, December 2000.
Saborio P , Tipton GA , Chan JCM. Diabetes insipidus. Peds Rev. 2000;21(4):122–129.
Ozier Y , Bellamy L. Pharmacological agents: Antifibrinolytics and desmopressin. Best Pract Res Clin Anaesthesiol. 2010;24:107–110.

http://www.diabetesinsipidus.org/whatisdi.htm

See Also (Topic, Algorithm, Electronic Media Element)

Hypernatremia
Syndrome of Inappropriate Antidiuretic Hormone (SIADH) Release
Serum Osmolality
Urine Osmolality

ICD9

253.5 Diabetes insipidus

ICD10

E23.2 Diabetes insipidus

Diabetes insipidus results from a deficiency in ADH secretion or abnormal renal response to ADH.
It manifests as polyuria/polydipsia with low urine osmolarity and hypernatremia.
May present following neurosurgery, especially surgery of the pituitary or hypothalamus
Usually presents within the first 24–48 hours postoperatively and is transient

Keren Ziv , MD

Linzy Fitzsimons , MD

section name header

Basics ⬇

Incidence

Prevalence

Morbidity

Mortality

Diagnosis ⬆ ⬇

History

Signs/Physical Exam

Labs/Studies

Treatment ⬆ ⬇

Premedications

Choice of Anesthesia

Monitors

Induction/Airway Management

Maintenance

Extubation/Emergence

Follow-Up ⬆ ⬇

References ⬆ ⬇

Additional Reading ⬆ ⬇

Codes ⬆ ⬇

Clinical Pearls ⬆ ⬇

Author(s) ⬆