“Hyponatremia and hypernatremia are common findings in the inpatient and outpatient settings. Sodium disorders are associated with an increased risk of morbidity and mortality. Plasma osmolality plays a critical role in the pathophysiology and treatment of sodium disorders. Hyponatremia and hypernatremia are classified based on volume status (hypovolemia, euvolemia, and hypervolemia). Sodium disorders are diagnosed by findings from the history, physical examination, laboratory studies, and evaluation of volume status. Treatment is based on symptoms and underlying causes. In general, hyponatremia is treated with fluid restriction (in the setting of euvolemia), isotonic saline (in hypovolemia), and diuresis (in hypervolemia).”

Diagnostic Approach to Hyponatremia
“Symptoms of hyponatremia depend on its severity and on the rate of sodium decline. Gradual decreases in sodium usually result in minimal symptoms, whereas rapid decreases can result in severe symptoms. Polydipsia, muscle cramps, headaches, falls, confusion, altered mental status, obtundation, coma, and status epilepticus may indicate the need for acute intervention.”

Hypernatremia
“Hypernatremia is defined as a serum sodium level greaterthan 145 mEq per L. It is associated with increased morbid–ity and mortality in the inpatient setting.31,32 Hypernatre–mia is caused by net water loss (increased loss or decreasedintake) or, rarely, sodium gain. Patients at increased riskinclude those with an impaired thirst mechanism orrestricted access to water“

Braun MM, et al Diagnosis and management of sodium disorders: hyponatremia and hypernatremia. Am Fam Physician. 2015 Mar 1;91(5):299-307. Free Full Text