Endocrine Abstracts

Introduction: Hyponatraemia is one of the most common electrolyte abnormalities seen in clinical practice [1] and can be caused by a myriad of aetiologies.

Aim: To report two cases of severe hyponatraemia caused by different aetiologies.

Case report: A 56-year-old male patient was admitted with 2 episodes of tonic-clonic seizures at his care home. The patient had a background of small cell lung cancer and brain metastases in late 2020. Laboratory investigations revealed a sodium level of 101 mmol/l, serum osmolality of 250 mosm/kg, urine osmolality of 457 mosm/kg and urine sodium of 158.6 mmol/l. His CT head showed a left occipital lobe cystic lesion with some surrounding vasogenic oedema. The cause was multifactorial with relative glucorticoid deficiency and a degree of cerebral salt wasting. Sodium was increased by initially slow IV saline (and some fluid restriction), increased dose of dexamethasone (4 mg from 2 mg) and demeclocycline 300 mg. Similarly, a 73-year-old female patient presented to hospital with dizziness and a fall. The patient has a background of hypertension, type 2 diabetes mellitus and mild axonal neuropathy for which she took bendroflumethiazide 2.5 mg OD, omeprazole 20 mg, candesartan 10mg OD, felodipine 2.5 mg OD, gliclazide 40 mg and simvastatin 20 mg ON. Blood tests revealed sodium of 100 mmol/l with a serum osmolality of 214 mosm/kg, urine osmolality of 272 mosm/kg and urine sodium of 41.2 mmol/l. The cause was determined as drug-induced, the most likely culprits being a thiazide and omeprazole, and appropriately stopped along with fluid restriction of 1.5L/day.

Conclusion: Both cases presented with varied clinical presentations and causes but both with profound hyponatraemia of 100 mmol/l. There are profound risks associated with this yet with precision in diagnostics and selective treatment plans, both patients had excellent outcomes with restoration of sodium levels.