MRCP2-1948

MRCP2-1948

A 42-year old teacher is brought to the Emergency Department after having taken 30 paracetamol tablets with a bottle of wine 6 hours prior to admission, following a stressful day at work. She feels dizzy and complains of stomach pain. There is no past medical history of note and she takes occasional aspirin tablets. She drinks about 10 units of alcohol per week. Physical examination is normal.

Investigations:
Sodium (Na+) 138 mmol/l 135 – 145 mmol/l
Potassium (K+) 4.2 mmol/l 3.5 – 5.0 mmol/l
Urea 4.5 mmol/l 2.5 – 6.5 mmol/l
Creatinine (Cr) 70 µmol/l 50 – 120 µmol/l
Bicarbonate (HCO3-) 22 mmol/l 22 – 29 mmol/l
International normalized ratio (INR) 1.0 < 1.1
Serum ibuprofen level 300 mg/l 100 – 200 mg/l

Which of the following is the most useful prognostic indicator when tested the next day?