Endocrine Abstracts

Introduction: Hyponatraemia is a common electrolyte disturbance in hospital inpatients and a frequent reason for referral to Endocrinology. Hyponatraemia is a marker for an underlying pathology and fluid status rather than a diagnosis per se. Syndrome of inappropriate antidiuretic hormone secretion (SIADH) occurs as a complication of several medical presentations. The aim of this retrospective audit was to assess inpatient referrals of hyponatraemia to the Endocrinology team and identify ways to reduce workload using the RCP Referring wisely document.

Methods: Hyponatraemia referrals received via the electronic referral system over a 6-month period (January-June 2024) were analysed. Clinical judgement on aetiology of hyponatraemia was derived based on a comprehensive review of these referrals.

Results: n =76 (18% of total referrals received) Sodium at referral: Mild: 130-135mmol/L (2.6%) Moderate: 125-129mmol/L (40.8%) Severe: <125mmol/L (56.6%). Mean time of referral following onset of hyponatraemia: Day 6 (between day 1 to day 25). Referring departments: Medical wards (73%), surgical wards (26%), intensive care (1%). Hyponatraemia blood screening panel prior to referrals: 59% were performed. Likely cause of hyponatraemia: Drug induced (27.6%) SIADH (26.3%) Fluid overload (13.2%) Dehydration (13.2%) Unclear cause (10.5%) Multifactorial (7.9%) Primary endocrine pathology (1.3%).

Conclusion: This audit demonstrates that over half of inpatient referrals for hyponatraemia to Endocrinology had a drug/fluid balance precipitant. These could have been avoided by use of the comprehensive Trust guidelines. A systematic diagnostic approach, by the primary team (majority from physician sub-specialties), is warranted to determine the aetiology of hyponatraemia. In view of the various non-endocrine causes of hyponatremia and the higher prevalence during inpatient stay, there is a need to follow Referring wisely RCP guidance stating referral to Endocrinology for ‘Symptomatic or severe hyponatraemia or where diagnostic doubt exists’. This is pertinent when majority of the causes for hyponatraemia is not due to a primary endocrinopathy.