Life-threatening hyponatraemia.

Area of Science:

• Nephrology
• Cardiology
• Pharmacology

Background:

• Hypertension management often involves diuretics like bendroflumethiazide.
• Thiazide diuretics can cause electrolyte imbalances, including hyponatremia and hypokalemia.
• Concurrent use of ACE inhibitors like ramipril may influence these effects.

Observation:

• A 31-year-old woman presented with palpitations and was treated with bendroflumethiazide and ramipril.
• Telemetry revealed ventricular bigeminy, and initial labs showed mild hyponatremia (132 mmol/l) and hypokalemia (3.4 mmol/l).
• The patient subsequently experienced neurological symptoms (paresthesiae, weakness, confusion, seizures) and asystole.

Findings:

• A critical drop in serum sodium to 120 mmol/l and potassium to 2.3 mmol/l was observed preceding the neurological and cardiac events.
• These severe electrolyte disturbances were temporally associated with high-dose thiazide diuretic therapy.
• Discontinuation of bendroflumethiazide and ramipril, fluid restriction, and potassium supplementation led to normalization of electrolytes and patient recovery.

Implications:

• This case highlights the potential for severe, life-threatening hyponatremia and hypokalemia induced by thiazide diuretics, even in younger patients.
• It underscores the importance of vigilant electrolyte monitoring in patients on diuretic therapy, especially with dose increases or combination therapy.
• Awareness of these risks is crucial for preventing severe adverse events and guiding appropriate management strategies in clinical practice.