Prevalence, risk factors, and short-term consequences of traumatic brain injury-associated hyponatremia

Hyponatremia, a common electrolyte disorder associated with traumatic brain injuries (TBIs), has high mortality and morbidity rates. The aim of this study was to identify the risk factors for hyponatremia associated with TBI. We retrospectively analyzed the cases of TBI patients who were admitted to the emergency intensive care unit at Okayama University Hospital between October 2011 and September 2014. A total of 82 TBI patients were enrolled. The incidences of hyponatremia (serum sodium level of＜135mEq/L) and severe hyponatremia (serum sodium level of＜130mEq/L) within the first 14 days after admission were 51% (n＝42) and 20% (n＝16), respectively. After admission, hyponatremia took a median period of 7 days to develop and lasted for a median of 3 days. Multivariate analysis demonstrated that higher fluid intake from days 1 to 3 and the presence of cranial fractures were risk factors for hyponatremia. The 58 patients with hyponatremia experienced fewer ventilator-free days, longer intensive care unit stays, and less favorable outcomes compared to the 24 patients without hyponatremia;however, these differences were not significant. Further studies are needed to determine the optimal management strategy for TBI-associated hyponatremia in the intensive care unit setting.