Endocrine Abstracts (2013) 32 P708 | DOI: 10.1530/endoabs.32.P708

Hyponatremia in the emergency room: characteristics, and initial diagnostic approach

Martin Cuesta Hernandez, Emilia Gomez Hoyos, Francisco Fernandez Capel, Teresa Ruiz Gracia, Alfonso Calle Pascual, Javier Martin Sanchez & Isabelle Runkle De La Vega


Hospital Clinico San Carlos, Madrid, Spain.


Introduction: Hyponatremia is common in the emergency room, albeit frequently overlooked. Our objective was to describe the characteristics of hyponatremia in a cohort of emergency room patients, and evaluate how hyponatremia was studied and followed up.

Material and methods: We studied all 211 patients under 70 years-of-age who presented/developed non-translocational hyponatremia (serum sodium (SNa) <135 mmol/l) during the first 48 h of their stay at the emergency room of our general hospital in August 2012. Patients are classified by physical examination and the presence of hemodilution or hemoconcentration (urea/creatinine, hematocrit).

Results: Average age was 47 (S.D. 16), 54.5% (115) were women. 31% (66) had presented hyponatremia previously. 8.5% (18) were hypovolemic, 3.3% (7) hypervolemic, 62.6% (132) euvolemic (64.8% of whom experienced pain, 40.8% nausea, 29% both). 25.6% (54) lacked sufficient data for classification. Mean initial SNa: 132.3 mmol/l (S.D. 3.35), Mean nadir SNa: 131.6 mmol/l (S.D. 3). 5.6% (12) presented polydipsia. 31.8% (67) were medicated with selective serotonin reuptake inhibitors, 6.6% (14) thiazides, 6.6% (14) opiates, 7.6% (16) benzodiazepines, 6.6% (14) antiepileptics, 2.8% (6) antipsychotics. Only 7 (3.3%) patients had osmolality (plasma/urine) determined, 13 (6.2%) urine electrolytes. 21% had TSH levels. Only two patients had cortisolemia measured. A comprehensive diagnostic study of hyponatremia (physical exploration and laboratory tests) was undertaken only by Endocrinologists. In 34% (72) SNa levels improved within 24 h, in 17.5% (37) they dropped. In the rest SNa remained stable or was not repeated. 2.8% (6) developed overcorrection of SNa. None were relowered. The most common principal diagnoses were urinary tract infection: 10.5% (22), neoplasia: 8.5% (18) – a third of whom had ENT cancer – and gastroenteritis: 7.6% (16). In 1.4% (3) hyponatremia was the principal diagnosis and in 15.2% (32) a codified diagnosis. After discharge, 36% (27) of the 75 patients with follow-up data remained hyponatremic.

Conclusions: In a majority of cases, hyponatremia was inadequately studied in the emergency room of our hospital, hindering a correct diagnosis and treatment of this important disorder.

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