Endocrine Abstracts

Background: Hyponatraemia is the most common electrolyte abnormality encountered in hospitals and has been independently associated with increased morbidity and mortality¹. An appropriate work-up with guideline-based investigations and management is, therefore, crucial to allow accurate diagnosis and optimisation of patient care.

Case Presentation: A 49-year-old with no significant past medical history presented with 2 weeks of persistent nausea and lethargy, alongside worsening headaches. Sodium levels were 116 mmol/l on admission, without an apparent acute cause. Further assessment revealed secondary hypothyroidism and unrecordable cortisol levels, in keeping with hypopituitarism. Urgent MRI scanning was performed to exclude pituitary apoplexy; this ruled out haemorrhage but demonstrated a solitary pituitary lesion, likely having caused chronic pituitary failure and insidious development of hyponatraemia. Outcome Commencing glucocorticoid replacement therapy caused a rapid correction of sodium levels and the resolution of the patient’s symptoms. Growth hormone, thyroxine and testosterone replacement were initiated, and the patient reported substantially improved quality of life, feeling ‘like a new person’. Follow-up scans revealed shrinkage of the lesion, with no operative intervention necessitated.

Discussion: This case describes a rare cause of hyponatraemia and highlights the importance of maintaining open differential diagnosis for patients, given the variety of potential aetiologies. Studies have shown that misdiagnosis of chronic hypopituitarism occurs frequently; often due to poor compliance to diagnostic criteria such as those for the syndrome of inappropriate ADH hormone secretion (SIADH)². Local audit of hyponatraemia work-up revealed deficiencies in comparison to the latest ESE guidelines. A subsequent literature review of published UK audits on hyponatraemia demonstrated country-wide issues with guideline adherence. When combined with the significant benefits an accurate diagnosis provided this patient, our research gives evidence to highlight a need for further work to raise awareness of hyponatraemia investigation and management amongst clinicians, in order to ensure optimal patient outcomes.

References: 1. Dineen R, Thompson CJ, Sherlock M. Hyponatraemia – presentations and management. Clin Med (Lond). 2017 Jun;17(3):263-9.

2. Cuesta M, Garrahy A, Slattery D, Gupta S, Hannon AM, Forde H, et al. The contribution of undiagnosed adrenal insufficiency to euvolaemic hyponatraemia: results of a large prospective single-centre study. Clin Endocrinol (Oxf). 2016 Dec;85(6):836-44.