How should I manage a patient with mild hypernatraemia (sodium levels 145-150 mmol/L) without significant symptoms?

Management of a patient with mild hypernatremia (sodium 145-150 mmol/L) who is asymptomatic:

• Assess the patient's hydration status and clinical context to identify any underlying causes or contributing factors.
• If the patient is clinically euvolemic and asymptomatic, close monitoring with repeat serum sodium measurements is appropriate to ensure sodium levels do not rise further or cause symptoms.
• If dehydration is present, calculate the water deficit and replace it cautiously over 48 hours, initially using isotonic saline (0.9% sodium chloride), then consider hypotonic fluids if hypernatremia persists or worsens.
• Ensure the rate of correction of hypernatremia does not exceed a fall of 12 mmol/L in 24 hours to avoid cerebral edema.
• Monitor plasma electrolytes every 4 to 6 hours during initial treatment, adjusting fluid therapy based on response.
• Treat any underlying acute illness or discontinue medications that may contribute to hypernatremia if appropriate.
• Referral to specialist care is generally not required if the patient remains asymptomatic and stable, but consider it if hypernatremia worsens or if there is uncertainty about the cause or management.

This approach balances cautious correction of sodium with prevention of complications and is based on expert consensus and NICE guidelines on intravenous fluid therapy and electrolyte management in adults and children NICE NG29,NICE CG174.