Plasma sodium concentration in older patients as an indicator of severity in emergencies: Results from the Emergency Department and Elder Needs-16 study

Pere Llorens1, Òscar Miró2, Mónica Veguillas Benito1, Cesáreo Fernández3, Javier Jacob4, Guillermo Burillo-Putze5, Aitor Alquézar6, Sira Aguiló2, Margarita Puiggali Ballard7, Sierra Bretones Baena8, Jeong-Uh Hong Cho9, Melisa San Julián Romero10, María Eugenia Rodríguez Palma11, Alberto Álvarez Madrigal12, María Rodríguez Romero13, María Isabel Lozano López14, Rebeca González González15, Marina Carrión Fernández16, Belén Morales Franco17, Eduard Antón Poch Ferrer18, Violeta González Guillén19, Sara Gayoso Martín20, Goretti Sánchez Sindín21, Azucena Prieto Zapico22, Paola Ponte Márquez6, Begoña Espinosa1, Juan González del Castillo3 (en representación de la red SIESTA)

Affiliation of the authors

1Emergency Department, Short-Stay and Short Stay and Home Hospitalization Unit, Hospital Doctor Balmis Hospital, Alicante, Institute of Health and Biomedical Research Institute of Alicante (ISABIAL), Miguel Hernández University, Alicante, Spain. 2Emergency Department, Hospital Clínic, IDIBAPS, University of Barcelona Barcelona, Barcelona, Spain. 3Emergency Department, Hospital Clínico San Carlos, IDISSC, Complutense University, Madrid, Spain. 4Emergency department, Hospital Universitari de Bellvitge, l’Hospitalet de Llobregat, Barcelona, Spain. 5Emergency department, Hospital Universitario de Canarias, Tenerife, Spain. Facultad de Ciencias de la Salud, Universidad Europea de Canarias, Tenerife, Spain. 6Emergency department, Hospital de la Santa Creu i Sant Pau, Barcelona, Spain. 7Emergency department, Hospital del Mar, Barcelona, Spain. 8Emergency department, Hospital Reina Sofía, Córdoba, Spain. 9Emergency department, Hospital de Mendaro, Guipuzcoa, Spain. 10Emergency department, Hospital Universitario Gregorio Marañón, Madrid, Spain. 11Emergency department, Hospital Universitario de Burgos, Spain. 12Emergency department, Complejo Asistencial Universitario de León, Spain. 13Emergency department, Hospital Universitario Morales Meseguer, Murcia, Spain. 14Emergency department, Hospital Francecs de Borja de Gandía, Spain. 15Emergency department, Hospital Universitario Severo Ochoa, Leganés, Spain. 16Emergency department, Hospital Universitario Virgen Arrixaca, Murcia, Spain. 17Emergency department, Hospital Universitario Lorenzo Guirao, Cieza, Spain. 18Emergency department, Hospital Josep Trueta, Girona, Spain. 19Emergency department, Hospital Miguel Servet, Zaragoza, Spain. 20Emergency department, Hospital Comarcal El Escorial, Madrid, Spain. 21Emergency department, Hospital Do Salnes, Villagarcía de Arosa, Spain. 22Emergency department, Hospital de Barbanza, Ribeira, A Coruña, Spain.



Llorens P, Miró O, Veguillas Benito M, Fernández C, Jacob J, Burillo-Putze G, et al. Plasma sodium concentration in older patients as an indicator of severity in emergencies: Results from the Emergency Department and Elder Needs-16 study. Emergencias. 2023;35:279-87



To study baseline factors associated with hypo- and hypernatremia in older patients attended in emergency departments (EDs) and explore the association between these dysnatremias and indicators of severity in an emergency.


We included patients attended in 52 Spanish hospital EDs aged 65 years or older during a designated week. All included patients had to have a plasma sodium concentration on record. Patients were distributed in 3 groups according to sodium levels: normal, 135-145 mmol/L; hyponatremia, < 135 mmol/L; or hypernatremia > 145 mmol/L. We analyzed associations between sodium concentration and 24 variables (sociodemographic information, measures of comorbidity and baseline functional status, and ongoing treatment for hypo- or hypernatremia). Indicators of the severity in emergencies were need for hospitalization, in-hospital mortality, prolonged ED stay (> 12 hours) in discharged patients, and prolonged hospital stay (> 7 days) in admitted patients. We used restricted cubic spline curves to analyze the associations between sodium concentration and severity indicators, using 140 mmol/L as the reference.


A total of 13 368 patients were included. Hyponatremia was diagnosed in 13.5% and hypernatremia in 2.9%. Hyponatremia was associated with age ($ 80 years), hypertension, diabetes mellitus, an active neoplasm, chronic liver disease, dementia, chemotherapy, and needing help to walk. Hypernatremia was associated with needing help to walk and dementia. The percentages of cases with severity indicators were as follows: hospital admission, 40.8%; in-hospital mortality, 4.3%; prolonged ED stay, 15.9%; and prolonged hospital stay, 49.8%. Odds ratios revealed associations between lower sodium concentration cut points in patients with hyponatremia and increasing need for hospitalization (130 mmol/L, 2.24 [IC 95%, 2.00-2.52]; 120 mmol/L, 4.13 [3.08-5.56]; and 110 mmol/L, 7.61 [4.53-12.8]); risk for in-hospital death (130 mmol/L, 3.07 [2.40-3.92]; 120 mmol/L, 6.34 [4.22-9.53]; and 110 mmol/L, 13.1 [6.53-26.3]); and risk for prolonged ED stay (130 mmol/L, 1.59 [1.30-1.95]; 120 mmol/L, 2.77 [1.69-4.56]; and 110 mmol/L, 4.83 [2.03-11.5]). Higher sodium levels in patients with hypernatremia were associated with increasing need for hospitalization (150 mmol/L, 1.94 [1.61-2.34]; 160 mmol/L, 4.45 [2.88-6.87]; 170 mmol/L, 10.2 [5.1-20.3]; and 180 mmol/L, 23.3 [9.03-60.3]); risk for in-hospital death (150 mmol/L, 2.77 [2.16-3.55]; 160 mmol/L, 6.33 [4.11-9.75]; 170 mmol/L, 14.5 [7.45-28.1]; and 180 mmol/L, 33.1 [13.3-82.3]); and risk for prolonged ED stay (150 mmol/L, 2.03 [1.48-2.79]; 160 mmol/L, 4.23 [2.03-8.84]; 170 mmol/L, 8.83 [2.74-28.4]; and 180 mmol/L, 18.4 [3.69-91.7]). We found no association between either type of dysnatremia and prolonged hospital stay.
Conclusion. Measurement of sodium plasma concentration in older patients in the ED can identify hypo- and hypernatremia, which are associated with higher risk for hospitalization, death, and prolonged ED stays regardless of the condition that gave rise to the dysnatremia.


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