Hyponatremia associated with tolterodine therapy

Area of Science:

• Geriatric Medicine
• Clinical Pharmacology
• Nephrology

Background:

• Hyponatremia, a common electrolyte imbalance, can result from various factors, including medication side effects.
• Tolterodine is a medication commonly prescribed for overactive bladder symptoms.

Observation:

• An 86-year-old female presented with altered mental status, found to have severe hyponatremia (serum sodium 125 mmol/L).
• Initial management including fluid restriction and intravenous saline failed to correct the hyponatremia.
• Other potential causes and medications, including hydrochlorothiazide, were ruled out.

Findings:

• Tolterodine, recently initiated, was identified as the likely cause of the patient's hyponatremia.
• Discontinuation of tolterodine on hospital day 5 led to rapid correction of serum sodium levels by the following day.

Implications:

• This case highlights the potential for tolterodine to cause hyponatremia, even in the absence of other risk factors.
• Clinicians should consider tolterodine as a potential cause of hyponatremia in elderly patients, particularly after recent initiation of therapy.
• Early recognition and discontinuation of the offending agent are crucial for effective management of drug-induced hyponatremia.