MSFinals-5862

MSFinals-5862

A 36-year-old woman of African origin presented to the Emergency Department with sudden-onset dyspnoea. She was a known case of systemic lupus erythematosus (SLE), previously treated for nephropathy and presently on mycophenolate mofetil and hydroxychloroquine sulfate. She had no fever. On examination, her respiratory rate was 45 breaths per minute, with coarse crepitations in the right lung base. After admission, blood test results revealed:
Investigation Value Normal range
Haemoglobin 100g/l 115–155 g/l
Sodium (Na+) 136 mmol/l 135–145 mmol/l
Potassium (K+) 4.7 mmol/l 3.5–5.0 mmol/l
PaO2on room air 85 mmHg 95–100 mmHg
C-reactive protein (CRP) 6.6mg/l 0-10 mg/l
C3 level 41 mg/dl 83–180 mg/dl
Which of the following is most likely to be found in this patient as the cause for her dyspnoea?