What are the symptoms and treatment of hyponatremia?

Symptoms of Hyponatremia

Clinical Manifestations by Severity

Hyponatremia presents with symptoms ranging from subtle cognitive changes in mild cases to life-threatening neurological emergencies in severe cases, with symptom severity depending on both the absolute sodium level and the rapidity of onset. 1

Mild to Moderate Hyponatremia (125-134 mEq/L)

• Nausea and vomiting are common early symptoms 1, 2
• Muscle cramps and generalized weakness occur frequently 1
• Gait instability and balance disturbances increase fall risk significantly 1
• Headaches and dizziness are typical presenting complaints 1, 2
• Lethargy and reduced energy levels 1
• Mild neurocognitive deficits, including altered memory and impaired complex information processing 1, 2

Severe Hyponatremia (<120 mEq/L)

Severe hyponatremia constitutes a medical emergency requiring immediate intervention. 1

• Confusion and delirium represent serious neurological involvement 1, 2
• Altered consciousness progressing to obtundation 1, 3
• Seizures indicate severe cerebral edema 1, 3, 2
• Coma in advanced cases 1, 3
• Respiratory distress may occur with severe encephalopathy 3
• Ataxia and impaired coordination 2
• Brain herniation and death in untreated cases 1, 2

Consequences of Chronic Hyponatremia

Even mild chronic hyponatremia (130-135 mEq/L) is not benign and should never be dismissed as clinically insignificant. 1

Cognitive and Neurological Impact

• Cognitive impairment with altered memory and complex information processing 1
• Increased fall risk: 23.8% of hyponatremic patients report falls versus 16.4% with normal sodium (p<0.01) 3
• Gait disturbances contributing to mobility problems 3

Musculoskeletal Complications

• Increased fracture risk: 23.3% versus 17.3% over 7.4 years follow-up (p<0.004) 3
• Secondary osteoporosis develops with chronic hyponatremia 3

Mortality Risk

• 60-fold increased hospital mortality risk for sodium <130 mEq/L (11.2% versus 0.19%) 1
• Increased hospital length of stay even with mild hyponatremia 3

Special Population Risks

In cirrhotic patients, hyponatremia significantly increases risk of:

• Spontaneous bacterial peritonitis (OR 3.40) 4
• Hepatorenal syndrome (OR 3.45) 4
• Hepatic encephalopathy (OR 2.36) 4

Symptom Onset and Acuity

The rapidity of sodium decline determines symptom severity more than the absolute sodium level. 3, 5

• Acute hyponatremia (<48 hours): More likely to cause severe symptoms even at higher sodium levels 5
• Chronic hyponatremia (>48 hours): May be better tolerated but still causes significant morbidity 5

Clinical Significance of Symptom Recognition

Correction of hyponatremia significantly improves cognitive functions, quality of life, and complex information processing. 1

• Early recognition prevents progression to severe complications 1
• Even mild symptoms warrant investigation and treatment 1
• Symptom severity guides urgency and aggressiveness of treatment 3, 2

Common Pitfall

Never ignore mild hyponatremia (130-135 mEq/L) as clinically insignificant, as it increases risk of falls, fractures, cognitive impairment, and mortality. 1