Hypernatremia
Basics
Description
Hypernatremia definition: Sodium >145 mEq/L:Description
- Mild hypernatremia: Serum sodium 146–155 mEq/L
- Severe hypernatremia: Serum sodium >155 mEq/L
Etiology
Divided into 3 categoriesEtiology
Hypovolemic Hypernatremia
- 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
Isovolemic Hypernatremia
- 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)
Hypervolemic Hypernatremia
- 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
- Iatrogenic – most common cause:
Pediatric Considerations
- More prone to iatrogenic causes
- More likely to die or to have permanent neurologic sequelae
- Morbidity ranges from 25–50% with mortality of 15%
- May present with high-pitched cry, lethargy, irritability, muscle weakness
- Poor breastfeeding and inappropriate formula preparations are a potential cause in neonates
- Breastfed infants among the highest risk groups to develop hypernatremia
- If hypernatremia is due to DKA, follow pediatric DKA protocols for fluid resuscitation
- DDAVP dose for 3 mo–12 yr is 5–30 mcg/d intranasally
- Consider NG hydration
Geriatric Considerations
- Most commonly affected group due to impaired renal concentrating ability and reduced thirst mechanism
- Consider neglect if underlying etiology is dehydration alone
Pregnancy Considerations
- 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
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Citation
Schaider, Jeffrey J., et al., editors. "Hypernatremia." 5-Minute Emergency Consult, 6th ed., Lippincott Williams & Wilkins, 2020. Emergency Central, emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307047/2.2/Hypernatremia.
Hypernatremia. In: Schaider JJJ, Barkin RMR, Hayden SRS, et al, eds. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307047/2.2/Hypernatremia. Accessed December 1, 2024.
Hypernatremia. (2020). In Schaider, J. J., Barkin, R. M., Hayden, S. R., Wolfe, R. E., Barkin, A. Z., Shayne, P., & Rosen, P. (Eds.), 5-Minute Emergency Consult (6th ed.). Lippincott Williams & Wilkins. https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307047/2.2/Hypernatremia
Hypernatremia [Internet]. In: Schaider JJJ, Barkin RMR, Hayden SRS, Wolfe RER, Barkin AZA, Shayne PP, Rosen PP, editors. 5-Minute Emergency Consult. Lippincott Williams & Wilkins; 2020. [cited 2024 December 01]. Available from: https://emergency.unboundmedicine.com/emergency/view/5-Minute_Emergency_Consult/307047/2.2/Hypernatremia.
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