8th February 2024

A 63-year-old female was admitted with decompensated heart failure.

A 63-year-old female was admitted with decompensated heart failure. She has a history of back pain for which she uses NSAIDs. Other medications include ramipril and bisoprolol. She is treated with high-dose diuretics to good effect. However, her urine output trails off a few days after her admission. Serum creatinine rises to 232 micromol/l (60-110) from a baseline of 160 micromol/l, and urea rises to 13 mmol/l (2.5-7.5). Urine osmolality is 980 mosmol/kg (350-1000 mosmol/kg), and urine electrolytes show a low sodium of 16 mmol/l.

Which of the following is the most likely diagnosis?