18th February 2025

A 62-year-old gentleman is seen in the oncology clinic. He has a background of metastatic squamous cell lung cancer, for which he is being treated

A 62-year-old gentleman is seen in the oncology clinic. He has a background of metastatic squamous cell lung cancer, for which he is being treated with paclitaxel chemotherapy with palliative intent. He has recently started complaining of generalised fatigue and constipation, which he had thought were side effects of his treatment. Routine pre-treatment bloods reveal: Na 135 mmol/L (133-146 mmol/L), K 3.9 mmol/L (3.5-5.3 mmol/L), Creatinine 101 µmol/L (45-104 µmol/L), Urea 4.8 mmol/L (2.5-7.8 mmol/L),  Phosphate 1.25 mmol/L (0.80-1.50 mmol/L), Magnesium 0.69 mmol/L (0.70-1.0 mmol/L), Calcium 3.62 mmol/L (2.20-2.60 mmol/L), CRP 23 mg/L (< 5mg/L).

What is the most likely underlying pathophysiology?

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