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5th April 2024
A 68-year-old pensioner with small cell lung cancer and type two diabetes is found confused by her carer, who came to administer morning medications.
A 68-year-old pensioner with small cell lung cancer and type two diabetes is found confused by her carer, who came to administer morning medications. In addition to her metformin and sitagliptin, her prescription chart shows a new prescription for duloxetine, which started last week. Admission bloods show:
| Sodium (135-145 mmol/L) | 114 mmol/L |
| Potassium (3.5-4.5 mmol/L) | 3.9 mmol/L |
| Urea (4-8.4 mmol/L) | 8.5 mmol/L |
| Glucose (below 7 mmol/L) | 18 mmol/L (negative ketones) |
| 9 am Cortisol (> 420 nmol/L) | 530 nmol/L |
On examination, she is euvolemic with a urine osmolality of 1300 mOsm/kg, urine sodium of 31 mmol/L and serum osmolality of 260 mOsmol/kg (reference range 280 – 295 mOsm/kg). What is the likely cause of her hyponatremia?
Select the SINGLE most appropriate option from the list below. Select ONE option only.
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