Classifying Hyponatremia by symptoms
No symptoms – Patients with hyponatremia are frequently asymptomatic, especially if the hyponatremia is chronic and of mild or moderate severity (ie, serum sodium >120 meq/L). However, such patients may have subclinical impairments in mentation and gait.
Mild to moderate symptoms – Mild to moderate symptoms of hyponatremia are relatively nonspecific and include headaches, nausea, vomiting, fatigue, gait disturbances, and confusion. In patients with chronic hyponatremia (ie, >48 hours duration), these findings are not associated with impending herniation; however, in patients with more acute hyponatremia, such symptoms should be considered ominous and may evolve without warning to seizures, respiratory arrest, and herniation.
Severe symptoms – Severe symptoms of hyponatremia include seizures, obtundation, coma, and respiratory arrest.
Classifying Hyponatremia by Sodium Concentration
Mild hyponatremia = a serum sodium concentration between 130 and 135 meq/L.
Moderate hyponatremia = A serum sodium concentration between 121 and 129 meq/L.
Severe hyponatremia = A serum sodium of 120 meq/L or less.