Prevalence and documented causes of hyponatraemia among geriatric patients attending a primary care clinic

INTRODUCTION: Hyponatraemia is the commonest electrolyte abnormality and has major clinical implications. However, few studies of hyponatraemia in the primary care setting has been published to date.

OBJECTIVES: To determine the prevalence, potential causes and management of hyponatraemia and to identify factors associated with severity of hyponatraemia among older persons in a primary care setting.

METHODS: Electronic records were searched to identify all cases aged ≥60 years with a serum sodium <135mmol/l, attending outpatient clinic in 2014. Patients' medical records with the available blood test results of glucose, potassium, urea and creatinine were reviewed.

RESULTS: Of the 21,544 elderly, 5873 patients (27.3%) had electrolyte profile tests. 403 (6.9%) had hyponatraemia in at least one blood test. Medical records were available for 253, mean age 72.9±7.3 years, 178 (70.4%) had mild hyponatraemia, 75 (29.6%) had moderate to severe hyponatraemia. Potential causes were documented in 101 (40%). Patients with moderate to severe hyponatraemia were five times more likely to have a cause of hyponatraemia documented (p<0.01). Medications were the commonest documented cause of hyponatraemia (31.7%). Hydrochlorothiazide use was attributed in 25 (78.1%) of 32 with medication-associated hyponatraemia. Repeat renal profile (89%) was the commonest management of hypotonic hyponatraemia.

CONCLUSION: Whilst hyponatraemia was common in the clinic setting, many cases were not acknowledged and had no clear management strategies. In view of mild hyponatraemia has deleterious consequences, future studies should determine whether appropriate management of mild hyponatraemia will lead to clinical improvement.