Can infections cause hyponatremia?

Yes, infections can cause hyponatremia and must be actively evaluated as a precipitant.

Infection is a recognized cause of hyponatremia through acute inflammation, and when hyponatremia occurs, it is essential to evaluate for infection with cultures, including diagnostic paracentesis in appropriate patients 1.

Mechanism and Clinical Context

Infections trigger hyponatremia through acute inflammatory responses that can signal underlying sepsis or localized infection. The most recent AGA guidelines (2025) explicitly state that hyponatremia may signal acute inflammation, making infection evaluation imperative 1.

When to Suspect Infection-Related Hyponatremia

• Any new or worsening hyponatremia warrants infection workup
• Hospitalized patients with symptomatic or severe hyponatremia (sodium <120 mEq/L) should be specifically evaluated for precipitating infections 1
• In cirrhotic patients with ascites, perform diagnostic paracentesis to rule out spontaneous bacterial peritonitis

Algorithmic Approach to Hyponatremia Evaluation

When encountering hyponatremia (serum sodium <130 mEq/L):

1. First, rule out non-hepatic causes including:

   • Infection (obtain cultures, consider paracentesis)
   • Thyroid dysfunction
   • Adrenal insufficiency
   • Cardiac disease
   • Renal disease
   • Medication effects (diuretics, laxatives)
   • Alcohol use

2. Document daily:

   • Sodium and fluid intake
   • Medication use
   • Stool frequency (if on laxatives)

3. If infection is identified, treat the underlying infection as the primary intervention 1

Critical Clinical Pitfall

Do not assume hyponatremia is solely due to volume overload or SIADH without excluding infection. Missing an underlying infection can lead to increased morbidity and mortality, as infection-related hyponatremia signals acute systemic inflammation requiring specific antimicrobial therapy rather than just fluid restriction.

The 2025 AGA guidelines emphasize this is particularly important in cirrhotic patients, where infection can precipitate acute decompensation and worsen outcomes beyond what the MELD score would predict 1.