Endocrine Abstracts

Case: A 25-year-old lady was incidentally found to have hyponatremia while she was investigated for painful left ankle and hand swelling. At the time of review in endocrine clinic, she was completely asymptomatic. Her menstrual period was normal. On examination she was found to be hypertensive with consistent blood pressure of 188/110. Rest of the systemic examination was unremarkable. Investigations revealed biochemical findings consistent with SIADH. Her serum sodium was 121 mmol/l, potassium 4.4 mmol/l, urea 1.7 mmol/l and creatinine 72 μmol/l. Her serum osmolality was 254 mosmol/kg, urine osmolality 455 mmol/kg and urine sodium 44 mmol/l. Her serum cortisol was 862 nmol/l and TSH was normal. SIADH was confirmed by serum AVP level of 0.68 pmol/l which should be undetectable at serum osmolality of 254 mosmol/kg.

Her chest X-ray was unremarkable. MRI of the brain showed complex developmental anomalies with absence of corpus callosum, dilatation of occipital horn of right lateral ventricle and anteriorly situated inter hemispheric cysts which was thought to be the cause of SIADH.

She was treated with 1.5 l of fluid restriction to maintain her serum sodium between 125 and 131 mmol/l. Her blood pressure was treated with doxazosin 2 mg daily after ruling out phaeochromocytoma and primary hyperaldosteronism.

Conclusion: This rare case highlights the importance performing thorough neurological assessment of patients presenting with asymptomatic hyponatremia.