Endocrine Abstracts

Introduction: Management of severe hyponatremia is challenging because of the need to balance the risk of overcorrection leading to osmotic demyelination syndrome (ODS) as well as under-correction causing complications, particularly in a patient with hypocortisolism and hypothyroidism. Case reports of patients with Noonan syndrome with hypopituitarism are rarely reported in literature. We report a case of a patient with Noonan syndrome and untreated anterior hypopituitarism who presented with symptomatic hyponatremia and developed transient episode of ODS.

Case presentation: A 50-year-old male presented with a two-day history of insomnia, severe nausea and dizziness. He was found to have hyponatremia (109 mmol/l). A thorough history taking revealed that he was found to have chronic anterior hypopituitarism with hypocortisolism, hypothyroidism and hypogonadism with 2 previous hospital admissions of severe hyponatremia in the last 15 years. However, each time, he would stop his hormonal treatment after a year and currently has stopped allmedications for 8 years. On examination, he had typical features of Noonan syndrome. He also had clinical features of hypogonadism which were bilateral gynecomastia, very small testes, and absent facial, pubic, and axillary hair. Initially, the sodium level risen from 109 mmol/l to 113 mmol/l over 22 hours. Despite careful administration of small volume of fluid (only 150 mls normal saline), hydrocortisone and levothyroxine replacement, his sodium level risen to 123 mmol/l over the next 15 hours. He developed a transient acute episode of hypertonia and aphasia due to ODS. Intravenous dextrose 5% fluid and desmopressin were used to lower his sodium level and his symptoms resolved. He made full recovery on discharge. Compared to his magnetic resonance imaging (MRI) pituitary fossa scanperformed 8 years ago which showed a non-enhancing 2 mm lesion in the left pituitary gland likely a non-functioning micro-adenoma, his repeat MRI pituitary scan was normal currently.

Conclusion: Patients with hyponatremia from chronic anterior hypocortisolism and hypothyroidism are a high risk of ODS. Careshould be taken to avoid a rise of >4–6 mmol/l per 24 hours. Early recognition, rescue desmopressin and dextrose 5% fluid to reduce serum sodium concentration were helpful to treat acute ODS.