MRCP2-3686

MRCP2-3686

A 50-year-old woman with recurrent breast cancer presents with confusion, abdominal pain and constipation. A recent bone scan did not reveal any ‘hot spots’.

Investigations reveal the following:

Sodium (Na+): 135 mmol/l (normal value: 135–145 mmol/l)

Potassium (K+): 3.4 mmol/l (normal value: 3.5–5.0 mmol/l)

Creatinine (Cr): 120 µmol/l (normal value: 50–120 µmol/l)

Urea: 10.0 mmol/l (normal value: 2.5–6.5 mmol/l)

Corrected calcium (Ca2+): 3.5 mmol/l (normal value: 2.20–2.60 mmol/l)

What is the most likely cause of her presentation?