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Hypernatremia, Emergency Medicine

Basics

Description

- Most common - Loss or deficiency of water and sodium with water losses being greater than sodium losses - Examples: - Renal failure - Medications (e.g., diuretics, lactulose) - Osmotic diuresis (mannitol, glucosuria, high protein feedings) - Insensible losses (burns, sweating) - Respiratory loss - Defective thirst mechanism - Lack of access to water - Diarrhea/vomiting - Intubated patients

- Water deficiency without sodium loss; free water loss - Examples: - Fever - Hypothalamic diabetes insipidus (DI): - Head trauma - Tumor - Congenital - Infection (TB, syphilis, mycoses, toxoplasmosis, encephalitis) - Granulomatous disease (sarcoid, Wegner) - Cerebrovascular accident - Aneurysm

- Nephrogenic DI: - Congenital - Drugs (lithium, amphotericin B, foscarnet, demeclocycline) - Obstructive uropathy - Chronic tubulointerstitial disease (sickle cell nephropathy, multiple myeloma, amyloidosis, sarcoidosis, systemic lupus erythematosus, polycystic kidney) - Electrolyte disorders (hypercalcemia, potassium depletion)

- Gain of water and sodium, with sodium gain greater than water gain. - Examples: - Iatrogenic-most common cause: - Sodium bicarbonate administration - NaCl tablets - Hypertonic parenteral hyperaliment - Hypertonic IV fluid (IVF) - Hypertonic dialysis

- Hypertonic medicine preparations such as ticarcillin and carbenicillin - Cushing disease - Adrenal hyperplasia - Primary aldosteronism - Sea water drownings

- Most symptoms attributed to underlying cause (e.g., dehydration) - More marked with acute changes - Death likely to occur with sodium of ≥185 mEq/L - May see the following symptoms, usually at levels ≥160 mEq/L: - Neurologic: - Headache - Tremulousness - Irritability - Ataxia - Mental confusion - Delirium - Seizures - Coma - Hyperreflexia - Asterixis - Chorea - Subarachnoid, intracerebral, and subdural hemorrhages - Dural sinus thrombosis

- Musculoskeletal: - Spasticity - Muscle weakness - Muscle twitching

- Other: - Anorexia - Tachypnea - Poor skin turgor - Nausea/vomiting

Hypernatremia definition: Sodium >145 mEq/L:

  • Mild hypernatremia: Serum sodium 146-155 mEq/L
  • Severe hypernatremia: Serum sodium >155 mEq/L

Etiology

Divided into 3 categories

Hypovolemic Hypernatremia

  • Most common
  • Loss or deficiency of water and sodium with water losses being greater than sodium losses
  • Examples:Renal failureMedications (e.g., diuretics, lactulose)Osmotic diuresis (mannitol, glucosuria, high protein feedings)Insensible losses (burns, sweating)Respiratory lossDefective thirst mechanismLack of access to waterDiarrhea/vomitingIntubated patients

Isovolemic Hypernatremia

  • Water deficiency without sodium loss; free water loss
  • Examples:FeverHypothalamic diabetes insipidus (DI):Head traumaTumorCongenitalInfection (TB, syphilis, mycoses, toxoplasmosis, encephalitis)Granulomatous disease (sarcoid, Wegner)Cerebrovascular accidentAneurysmNephrogenic DI:CongenitalDrugs (lithium, amphotericin B, foscarnet, demeclocycline)Obstructive uropathyChronic tubulointerstitial disease (sickle cell nephropathy, multiple myeloma, amyloidosis, sarcoidosis, systemic lupus erythematosus, polycystic kidney)Electrolyte disorders (hypercalcemia, potassium depletion)

Hypervolemic Hypernatremia

  • Gain of water and sodium, with sodium gain greater than water gain.
  • Examples:Iatrogenic-most common cause:Sodium bicarbonate administrationNaCl tabletsHypertonic parenteral hyperalimentHypertonic IV fluid (IVF)Hypertonic dialysisHypertonic medicine preparations such as ticarcillin and carbenicillinCushing diseaseAdrenal hyperplasiaPrimary aldosteronismSea water drownings
  • More prone to iatrogenic causes
  • More likely to die or to have permanent neurologic sequelae
  • Morbidity ranges from 25% to 50%.
  • May present with high-pitched cry, lethargy, irritability, muscle weakness
  • Poor breast feeding and inappropriate formula preparations are a potential cause in neonates
  • If hypernatremia is due to DKA, follow pediatric DKA protocols for fluid resuscitation
  • DDAVP dose for 3 mo-12 yr is 5-30 μg/day intranasally
  • Most commonly affected group due to impaired renal concentrating ability and reduced thirst mechanism
  • Consider neglect if underlying etiology is dehydration alone
  • May encounter transient DI of pregnancy
  • Vasopressin and desmopressin are category B drugs in pregnancy
  • Hydration status much more difficult to evaluate accurately by exam

Diagnosis

Signs and Symptoms

  • Most symptoms attributed to underlying cause (e.g., dehydration)
  • More marked with acute changes
  • Death likely to occur with sodium of ≥185 mEq/L
  • May see the following symptoms, usually at levels ≥160 mEq/L:Neurologic:HeadacheTremulousnessIrritabilityAtaxiaMental confusionDeliriumSeizuresComaHyperreflexiaAsterixisChoreaSubarachnoid, intracerebral, and subdural hemorrhagesDural sinus thrombosisMusculoskeletal:SpasticityMuscle weaknessMuscle twitchingOther:AnorexiaTachypneaPoor skin turgorNausea/vomiting

Hypovolemic Hypernatremia

  • Tachycardia
  • Orthostasis
  • Dry mucous membranes
  • Oliguria
  • Azotemia

Hypervolemic Hypernatremia

  • Pulmonary edema
  • Peripheral edema

Physical Exam

  • Evaluate for hydration status
  • Look at mucous membranes, neck veins, and skin turgor
  • Perform a complete neurologic exam and repeat throughout ED stay
  • Obtain orthostatic vital signs

Essential Workup

Serum Na+ level

Diagnosis Tests & Interpretation

Lab

  • Electrolytes, BUN/creatinine, glucose
  • CBC
  • Urinalysis:Specific gravityUrine/serum osmolalityUrine Na+

Imaging

  • CXR:For infection/aspirationPulmonary edema with hypervolemic hypernatremia
  • CT brain:For altered mental statusVenous sinus thrombosisSubarachnoid hemorrhagesSubdural hematoma

Diagnostic Procedures/Surgery

Consider Foley catheter to accurately monitor input and output

Differential Diagnosis

  • Diabetic ketoacidosis
  • Hyperosmolar coma
  • Primary CNS lesions

Treatment

Pre-Hospital

Volume resuscitation if hypovolemic or evidence of hemodynamic compromise

Initial Stabilization/Therapy

  • ABCs
  • 0.9% NS IV bolus for severe hypotension
  • Naloxone, thiamine, D50W (or Accu-Chek) for altered mental status

Ed Treatment/Procedures

General:

  • Calculate water deficit:Water deficit = 0.6 (weight in kg) — (1 - desired sodium/actual sodium)
  • Do not rapidly correct hypertonicity to normal serum osmolality:Rapid correction may cause seizures.Reduce serum sodium level by <0.5-0.7 mEq/L/hr.

Hypovolemic Hypernatremia

  • Replace volume contraction with 0.9% NS IV bolus.
  • Change to D5W or hypotonic saline once volume replenished and hemodynamically stable.

Isovolemic Hypernatremia

  • Calculate water deficit.
  • Correct water deficit with D5W or hypotonic saline:Replace half of deficit in 1st 24 hr, then remainder over 1-2 days.

Hypervolemic Hypernatremia

  • Remove excess water with diuretics or dialysis.
  • When euvolemic, replace water deficit with D5W.
  • Avoid hypertonic saline solutions because patient already has excess of total body sodium.

Diabetes Insipidus Hypernatremia

  • Sodium restriction
  • Desmopressin:Aqueous vasopressin (DDAVP)Best therapeutic agent
  • Chlorpropamide (Diabinese) enhances effect of vasopressin at renal tubule.
  • Carbamazepine causes release of vasopressin.
  • Hydrochlorothiazide enhances sodium excretion.
  • Discontinue DI-inducing drugs.

Medication

  • Chlorpropamide (Diabinese): 100-500 mg/d
  • Vasopressin (DDAVP): 1-2 μg IV/SC q12h or 5-20 μg intranasally

First Line

Volume correction starting initially with NS

Second Line

Correct the underlying cause.

Follow-Up

Disposition

Admission Criteria

  • Newly diagnosed sodium >150 mEq/L for monitoring and treatment
  • Admit sodium >160 mEq/L or symptomatic patients to ICU.

Discharge Criteria

  • Sodium <150 mEq/L in asymptomatic patient
  • Sodium >150 mEq/L in patients with history of chronically elevated sodium who are at their baseline and asymptomatic

Followup Recommendations

Repeat serum sodium levels within a week.

Pearls and Pitfalls

  • Up to 30% of acute hypernatremia patients will have permanent neurologic sequelae, a complete and well-documented neurologic exam is a must.
  • Patients at extreme ages and with chronic conditions are most susceptible to neurologic complications:On going fluid losses may require recalculation of fluid needsRepeat lab work to confirm controlled correction of sodium

Additional Reading

  • Ellison D. Disorders of sodium and water. Am J Kidney Dis. 2005;46(2):356-361.
  • Fall P. Hyponatremia and hypernatremia. A systematic approach to causes and their correction. Postgrad Med. 2000;107(5):75-82.
  • Lin M, Lu S, Lim I. Disorders of water imbalance. Emerg Med Clin North Am. 2005;23:749-770, ix.
  • Pfennig CL, Slovis CM. Sodium disorders in the emergency department: A review of hyponatremia and hypernatremia. Emerg Med Pract. 2012;14(10):1-20.
  • Ranadive SA, Rosenthal SM. Pediatric disorders of water balance. Endocrinol Metabol Clin North Am. 2009;38(4):663-672.

See Also (Topic, Algorithm, Electronic Media Element)

  • Diabetic Ketoacidosis
  • Hyperosmolar Coma
  • Hyponatremia

Codes

ICD9

  • 276.0 Hyperosmolality and/or hypernatremia
  • 775.5 Other transitory neonatal electrolyte disturbances

ICD10

  • E87.0 Hyperosmolality and hypernatremia
  • P74.2 Disturbances of sodium balance of newborn

SNOMED

  • 39355002 Hypernatremia (disorder)
  • 7405009 Acute hypernatremia
  • 12403008 Chronic hypernatremia (disorder)
  • 206489003 Transitory neonatal hypernatremia (disorder)