Endocrine Abstracts

Hyponatremia generally defined as a serum sodium of less than 135 mmol/l is the most common type of electrolyte imbalance found in older adults. Its mild to moderate forms can predispose patients to falls, fatigue and a general decline. Severe hyponatremia can contribute to seizures, confusion and death. We present a case of a 70-year-old lady with severe symptomatic chronic hyponatremia secondary to SIADH. She also had progressive Alzheimer’s dementia, anxiety, T1DM, hypertension, a stable meningioma, rheumatoid arthritis and hypercholesterolaemia. Her medication profile did not indicate any offending drugs and she was extensively investigated with no clear cause found for her SIADH. She was being managed with modified release slow sodium chloride tablets 1200 mg QDS in community and in the past been given short courses of demeclocycline and tolvaptan. Over the year previous to the endocrine clinic consultation, it was identified that she had multiple prolonged hospital presentations and inpatient admissions with increased confusion, absence seizures and agitation which then also destabilised her type 1 diabetes management. Sodium levels ranged between 114 -120 mmol/l. Due to her low sodium levels the memory clinic was hesitant to increase her memantine dose or prescribe anxiolytics for her Alzheimer’s dementia and anxiety and her mental health team suspected the hyponatraemia was contributing to her general decline. She had also begun to not tolerate the sodium chloride tablets. This resulted in a significant deterioration in her quality of life. She experienced heightened anxiety, confusion and agitation exacerbated by repeated hospital admissions. Aiming to reduce the frequency of hospital admissions the patient was trialled on Tolvaptan 7.5 mg twice a month commenced in January 2023. Tolvaptan functions as a selective vasopressin receptor antagonist at the renal collecting ducts which increases free water clearance and in turn raises serum sodium concentrations. Safety netting advise was given to the family to not administer at times of obvious dehydration. The trial proved to be a success whereby the patients’ sodium levels have largely been 125 mmol/l and above, thus also allowing her memantine doses to be increased. The patient has had no further hospital admissions in over a year and her grateful family reports that the patient is much happier, and her wider health has seen an improvement.