AKT-5521

A 72-year-old man is admitted to hospital with shortness of breath. He is diagnosed with atrial fibrillation and heart failure.

Whilst in hospital he is started on:
Aspirin 75 mg OD
Simvastatin 40 mg ON
Bisoprolol 5 mg OD
Digoxin 125 mcg OD
Ramipril 10 mg OD and
Furosemide 40 mg OD.

He comes to see you a few days after discharge complaining of feeling generally unwell. His wife tells you that he has been a bit confused and that he has vomited on several occasions. The patient also reports that his vision is blurred and has a yellow tinge to it.

On examination, he is in atrial fibrillation at a rate of 60 beats per minute, his chest is clear and he has minimal pedal oedema.

He was seen two days ago by the practice nurse for blood tests.
The results showed
Sodium 136 mmol/L (137 – 144)
Potassium 2.8 mmol/L (3.5 – 4.9)
Urea 6.4 mmol/L (2.5 – 7.5)
Creatinine 124 μmol/L (60 – 110)

What is the underlying cause of his unwellness?