20th July 2023

A 74-year-old woman with mild depression presents with a 3-day history of confusion, which seems to be getting worse.

A 74-year-old woman with mild depression presents with a 3-day history of confusion, which seems to be getting worse. She has also been complaining of nausea and a headache.

She has a past medical history of gastro-oesophageal reflux disease, previous ischaemic stroke, and hypertension.

Drug history: lercanidipine 10mg, clopidogrel 75mg and omeprazole 20mg.

Her observations are all within normal limits. She is not orientated to time, person or place and appears quite agitated at times. Physical examination is normal.

Blood results:

• Haemoglobin 122 g/l (115-165g/l)
  White cell count 8.3 x 10⁹/l (3.6-11.0 x 10⁹/l)
  CRP 2 mg/l (<5mg/l)
  Sodium 121 mmol/l (133-146 mmol/l)
  Potassium 4.3 mmol/l (3.5-5.3 mmol/l)
  Urea 4.5 mmol/l (2.5 – 7.8 mmol/l)
  Creatinine 66 μmol/l (59-104 μmol/l)

What is the most likely cause of her symptoms?

Select the SINGLE most appropriate option from the list below. Select ONE option only.