Skip to main content


You are about to leave

You are now leaving and are going to a website that is not owned or operated by OAPI.



It may not be what you think.

Find out what’s behind your patient's hyponatremia by learning about the types of hyponatremia and the etiologies and pathogenesis of all the different types.

About Hyponatremia

Hyponatremia is a common electrolyte disorder1

Hyponatremia is a common electrolyte disorder that occurs in up to 30% of all hospitalized patients.1,2 The disorder is important to recognize because it can have serious clinical consequences.3

Hyponatremia can be defined by:

  • Serum sodium concentration4 <135 mEq/L
  • Disorder of water balance
    • Body water is in excess relative to total body sodium5

Types of Hyponatremia

Hyponatremia can be classified by several clinical parameters, and treatment strategies are often based on a combination of these parameters.5

Incidence of hyponatremia is high
in hospitalized patients6

Using the definition of serum sodium <135 mEq/L, reported incidences of hyponatremia in both acutely and chronically hospitalized patients have been as high as 15 to 30%.6

Etiology & Pathogenesis

Hypotonic hyponatremia has multiple etiologies5,7,8

Etiologies can be categorized under the 3 main volume statuses: hypovolemic hyponatremia, euvolemic hyponatremia, and hypervolemic hyponatremia. Laboratory data and a physical exam will help assess patients’ volume status. The volume status will help determine the etiology of the hyponatremia.5,7,8

Hypotonic hyponatremia typically results from a
disruption in the excretion of water from the kidneys

This disruption in the excretion of water from the kidneys results in water retention, and is usually due to vasopressin release or renal failure.9

Symptoms & Risks

Hyponatremia can result in poor patient outcomes due to the following complications and risks:

Adverse effects on the brain3,6,10,11
Increased mortality risk12
Increased falls and fractures13-16

Hyponatremia signs and symptoms can range from
mild or nonspecific to severe

Nonspecific or mild symptoms of hyponatremia can progress quickly to severe symptoms. The more severe symptoms are often neurologic complications due to brain edema and increased intracranial pressure from severe and rapidly evolving hyponatremia3,6,10

Impact on Hospitals

Hyponatremia results in longer, more costly
hospital stays10,17-19

  • Hospital-acquired hyponatremia

    results in an increased length of hospital stay that is strongly associated with the severity of hospital-acquired hyponatremia10

  • Hyponatremia on admission

    results in longer,17 more costly hospital stays, with the costliest stays occurring in the more severe cases of hyponatremia17

  • Both hyponatremia on admission and
    hospital-acquired hyponatremia

    result in greater utilization of health care resources, and an increase in ICU admissions and hospital readmissions.18

Treatment Options

There are several different methods that physicians use to treat hyponatremia

These methods include the use of treatments such as:

Fluid Restriction5,19
Hypertonic Saline6,19
Isotonic Saline6
Loop Diuretics*5,6,19
Vasopressin Receptor Antagonists (Vaptans)5,19
*Not FDA-approved to treat hyponatremia.

Hyponatremia treatment approach depends on
several criteria

Criteria used in the treatment approach for hyponatremia depends on the rate of onset (acute or chronic) of hyponatremia,
the symptom status, and the volume status.6,10

Hyponatremia Resources

View resources covering several topics in hyponatremia

Watch educational videos.