Acid-Base and Electrolyte Disorders: Sodium Disorders

Sodium disorders are commonly encountered in clinical practice and are frequently misunderstood. Abnormal serum sodium levels are due to an imbalance in free water. Hyponatremia and hypernatremia can be asymptomatic if mild and chronic; however, acute and severe changes in sodium levels may cause substantial symptoms. In acute mild hyponatremia, symptoms can include confusion, vomiting, and weakness. In severe cases, seizures can occur. Determining the patient's volume status helps to determine the underlying etiology and appropriate treatment strategy. Euvolemic hyponatremia is the most common presentation due to the prevalence of syndrome of inappropriate antidiuretic hormone. Depending on severity, hyponatremia can be managed in the outpatient or inpatient setting. Management is directed at treating underlying causes and relieving severe symptoms while decreasing the risk of serious adverse effects from treatment. In patients with chronic hyponatremia without severe symptoms, rapid correction of serum sodium should be avoided to minimize the risk of osmotic demyelination syndrome. Hypernatremia is caused by a loss of free water, inadequate water intake, or salt overload. Patients with acute hypernatremia may present with fatigue, signs of dehydration, and weakness. Symptomatic acute and severe hypernatremia require inpatient admission and management of free water deficit with intravenous hypotonic fluids.