Diabetes Insipidus, Emergency Medicine

Basics

Description

Disorder in which large volumes of dilute urine are excreted (polyuria) as an inappropriate response to argininevasopressin (AVP)
Polyuria defined as >3 L in 24 hr
Often characterized by excessive fluid intake (polydipsia)
2 types:
- Central diabetes insipidus (DI, CDI; failure or deficiency of AVP release):
  - 4 types:
    - No AVP to release (loss or malfunction of posterior pituitary neurons)
    - Defective osmoreceptors-release AVP only in response to severe dehydration
    - Elevated threshold for AVP release
    - Subnormal amount of AVP released
  - Familial cases have been reported (autosomal dominant).
- Nephrogenic DI (lack of renal response to AVP):
  - Differentiate from primary polydipsia.
  - Some cases are X-linked recessive in males.

Etiology

Central DI:
- Any condition that disrupts the osmoreceptor-hypothalamus-hypophyseal axis:
- Highest incident in ages 10-20 yr
  - Trauma (skull fractures, hemorrhage)
  - Pituitary or hypothalamic surgery
  - CNS neoplasm: DI can be considered a tumor marker:
    - Pituitary adenomas
    - Craniopharyngiomas
    - Germinomas
    - Pinealomas
    - Meningiomas
  - Metastatic tumors:
    - Leukemia/lymphoma
  - Granulomatous:
    - Histiocytosis
    - Sarcoidosis
  - Congenital CNS defects
  - CNS infections (e.g., meningitis, encephalitis)
  - Pregnancy (Sheehan syndrome)
  - Idiopathic (autoantibodies, occult tumor)
  - Wolfram syndrome (DI, DM, optic atrophy, deafness)
  - Ethanol
Nephrogenic DI:
- Any condition that disrupts the kidney:
  - Congenital renal disorders
  - Obstructive uropathy
  - Renal dysplasia
  - Polycystic kidney disease
  - Systemic disease with renal involvement
  - Sickle cell disease
  - Sarcoidosis
  - Amyloidosis
  - Drugs:
    - Amphotericin
    - Phenytoin
    - Lithium (most common and persists past discontinuation of drug)
    - Aminoglycosides
    - Methoxyflurance
    - Demeclocycline
  - Electrolyte disorders:
    - Hypercalcemia
    - Hypokalemia

Transient in the 2nd trimester:
- Unclear etiology, but there is an increase of circulating vasopressinase.
- Leads to a decrease in AVP and transient DI
- Watch patient closely during anesthesia and periods of water restriction.
- Typically clears after 2-6 wk after delivery
- Desmopressin (DDAVP) resists this vasopressinase.
Sheehan syndrome may cause DI.

Diagnosis

Signs and Symptoms

History

Polyuria (up to 16-24 L/d of urine):
- Note the voiding frequency.
Polydipsia (often craves cold fluids):
- Note the amount of PO fluid intake per day.
Drug ingestion
Signs and symptoms of hypothalamic tumors:
- Headache
- Visual disturbances
- Growth disturbances
- Obesity
- Hyperpyrexia
- Sleep disturbances
- Sexual precocity
- Emotional disturbances

Physical Exam

Dehydration
Cachexia
Head trauma
Visual field defects
Seizures

Polyuria and polydipsia may not be recognized by caregivers until symptoms of dehydration develop.
In neonates:
- Often present at birth
- If unrecognized, dehydration and hypernatremia may cause permanent CNS damage.
In infants:
- Irritability
- Poor feeding/weight loss
- Constipation
- Growth failure
- Intermittent high fever
- Abnormal behavior (hyperactivity, restlessness, excessive crying)
In children:
- Enuresis
- Difficulty with toilet training

Essential Workup

Clinical diagnosis in the ED:
- Elevated serum sodium concentration
- Copious amounts of dilute urine
History:
- Usually an increased amount of PO fluid intake per day
- Voiding frequency
- Medication use history
Physical exam
Labs below

Diagnosis Tests & Interpretation

Lab

Urinalysis:
- Specific gravity will be low.
Serum and urine osmolality:
- High serum osmolality
- Low urine osmolality
Electrolytes, BUN, creatinine, and glucose:
- Hypernatremia
- Hypercalcemia
- Hypokalemia
CBC:
- Anemia may be a sign of a neoplasm.
Serum and urine AVP tests are expensive and unnecessary in the ED.

Imaging

As needed to evaluate for trauma or search for neoplasm
CXR
CT of brain
MRI of pituitary axis is usually outpatient.

Diagnostic Procedures/Surgery
Water deprivation test (dehydration test): �

Unnecessary in the emergency setting
Can be dangerous in cases of hypotension or small children
Performed as a confirmatory test for those receiving treatment
Measures urine and plasma osmolality after fluid restriction
- Urine osmo <300 is significant for DI
  - Desmopressin is administered
    - Central DI-urine osmo increased by >50%
    - Nephrogenic DI-urine osmo increased by <50%
- Further testing is needed if urine osmo 300-800
- Primary polydipsia if urine osmo >800

Differential Diagnosis

Primary water deficit:
- Inadequate access to free water
- Increased insensible water loss (e.g., premature infants)
- Inadequate breast-feeding
Primary sodium excess:
- Excessive sodium bicarbonate during resuscitation
- Hypernatremic enemas
- Ingestion of seawater
- Hypertonic saline administration
- Accidental substitution of salt (sodium chloride) for glucose in infant formulas
- Intentional salt poisoning
- High breast milk sodium
Primary polydipsia (psychogenic polydipsia):
- Solute-induced polyuria
- Diuretic use
- Resolving acute renal failure
- Osmotic diuresis
- Uncontrolled DM

Treatment

Pre-Hospital

ABCs
Immobilize if trauma is suspected.
Serum blood glucose
IV access and fluids if signs of dehydration exist
Control seizures according to medical direction guidelines.

Initial Stabilization/Therapy

Manage ABCs.
Manage traumatic injuries accordingly.
High index of suspicion for head trauma

Ed Treatment/Procedures

Correction of hypotension:
- Use of 0.9% NaCl is indicated for shock.
- Intravascular losses represent only about 1/12 of total water losses.
Central DI (vasopressin deficient):
- AVP (aqueous vasopressin):
  - Half-life is too short.
  - May induce coronary vasospasm
  - Used only for dehydration test
- Lysine vasopressin (lypressin):
  - Can be given intranasally
  - Frequent instillation needed
- Desmopressin:
  - Drug of choice to control symptoms
  - Administer intranasally, SC, IV, or PO in 2 divided doses as necessary to control polyuria or polydipsia.
  - Caution in postoperative patients as cerebral edema may develop
- Chlorpropamide (Diabinese):
  - Enhances effect of vasopressin at renal tubule
  - May stimulate AVP release
  - Useful only in partial CDI
  - Clofibrate stimulates the release of endogenous vasopressin.
Nephrogenic DI:
- Diuretics:
  - Induce natriuresis
  - Thiazides 1st line
  - Amiloride often used in combination with thiazides
- Dietary sodium restriction
- Restrict solutes and avoid excessive drinking to prevent water intoxication.
- Avoid alcohol (especially beer) intake.
- Check daily weights.
- NSAIDs (indomethacin)
Parenteral correction of initial water deficit in cases where PO is not an option:
- Usually only in symptomatic hypernatremic cases
- For fluid replacement, refer to "Hypernatremia."�

Medication

Aqueous AVP: 5-10 U SC in the unconscious patient from head trauma or postoperative
Amiloride: 2.5-10 mg PO BID
Chlorpropamide (Diabinese): 200-500 mg PO daily
Clofibrate (Atromid-S): 500 mg PO q6h
Desmopressin: 10-20 μg/d intranasally; 1-3 μg/d SC or IV; 0.1-1.2 μg/d PO
Hydrochlorothiazide (HCTZ): 50 mg PO daily (peds: 2-4 mg/kg QD-BID)
Lypressin nasal spray: 1-2 nasal spray TID-QID as needed

Follow-Up

Disposition

Admission Criteria

AMS
Seizure
Severe dehydration
Electrolyte abnormalities
Associated trauma
Patients requiring DDAVP testing or a trial of water restriction

Discharge Criteria

Known diagnosis of DI
Stable electrolytes
Adequately hydrated

Followup Recommendations

Referral to specialist depends on underlying etiology of DI. �

Pearls and Pitfalls

Check urine osmolality and consider DI in polyuria.
Central DI will typically respond to desmopressin.
Nephrogenic DI will not respond to ADH:
- Treat the underlying electrolyte abnormality, discontinue concerning drugs, and consult nephrology for further management.

Additional Reading

Di lorgi �N, Napoli �F, Allegri �AE, et al. Diabetes insipidus - diagnosis and management. Horm Res Paediatr. 2012;77:69-84.
Fenske �W, Allolio �B. Current state and future perspectives in the diagnosis of diabetes insipidus: A clinical review. J Clin Endocrinol Metab. 2012;97(10):3426-3437.
Gardner �DG, Shoback
�D, eds. Endocrine emergencies. In: Greenspans Basic & Clinical
Endocrinology. 9th ed. McGraw-Hill Professional; 2011.
Kliegman �RM. ed. Diabetes insipidus. In:
Nelson Textbook of Pediatrics. 19th ed. Philadelphia,
PA: Elsevier Saunders; 2011.
Makaryus �AN, McFarlane �SI. Diabetes insipidus: Diagnosis and treatment of a complex disease. Cleve Clin J Med. 2006;73:65-71.

Codes

ICD9

253.5 Diabetes insipidus
588.1 Nephrogenic diabetes insipidus

ICD10

E23.2 Diabetes insipidus
N25.1 Nephrogenic diabetes insipidus

SNOMED

15771004 Diabetes insipidus (disorder)
111395007 Nephrogenic diabetes insipidus (disorder)
42021008 Familial diabetes insipidus
45369008 Neurohypophyseal diabetes insipidus (disorder)
77274005 Idiopathic diabetes insipidus (disorder)

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