The pattern of plasma sodium abnormalities in an acute elderly care ward: a cross-sectional study.

Abstract

INTRODUCTION: The combination of ageing, illness, and medications can lead to hyponatraemia or hypernatraemia. AIMS: To describe the distribution of plasma sodium levels in older patients admitted to hospital. METHODS: We carried out a hospital based cross-sectional study examining 1,511 serum sodium concentrations ([Na+]) among 336 elderly patients and attempted to elucidate the cause(s) of the abnormal serum [Na+]. RESULTS: The study population had a mean age of 81.4. Ninety-two (27.4%) patients had hyponatraemia and seven patients (2.1%) had hypernatraemia during their hospitalisation. The distribution of [Na+] results was towards the lower end of the normal range. The mortality rate of patients with hyponatraemia was 14.1% and that of patients with normal serum [Na+] was 8.9%. Six patients with hypernatraemia died in hospital. Lower respiratory tract infection and medication accounted for the majority of cases. CONCLUSIONS: Deranged [Na+] is common among elderly patients admitted to hospital.