21st May 2025

You are asked to review a 76-year-old lady by the F1 as her bloods have shown a hyponatraemia of 120 mmol/L.

You are asked to review a 76-year-old lady by the F1 as her bloods have shown a hyponatraemia of 120 mmol/L.  Her serum osmolality is reduced at 250 mOsmol/Kg and she is noted to have a negative fluid balance of -1L. You decide to give this lady fluid replacement in the form of 0.9% saline to manage the dehydration. 

Which of the following is not a cause of hypovolaemic hyponatraemia? Please select only ONE answer.