Neuroendocrine-induced hyponatremia in patients with traumatic brain injury: a systematic review and meta-analysis of the epidemiology, factors and prognosis

Abstract Traumatic brain injury (TBI) is a common brain dysfunction due to an external force as opposed to disease-induced brain damage. TBI is a leading global cause of high morbidity and mortality rates in the neurosurgical department. It contributes to ~30% of deaths related to brain damage. A common complication of TBIs is hyponatremia secondary to neuroendocrine causes, including syndrome of inappropriate antidiuretic hormone (SIADH), cerebral salt wasting syndrome and adrenal insufficiency. Most recent studies suggest SIADH as the main cause of hyponatremia in TBI. This study aims to evaluate the effects of neuroendocrine-induced hyponatremia on the prognosis of TBI, demonstrate the epidemiology of hyponatremia in patients with TBI, assess all possible etiologies of hyponatremia in TBI, determine the prognostic outcomes of hyponatremia in TBI and determine the effect of hyponatremia on the prognosis of severe and moderate TBI. This study is in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analysis 2020 guideline. A 10-year retrospective analysis of original published studies from January 2013 to January 2023 will be performed. This study will include the adult TBI patients (age ≥ 18 years old) who developed neuroendocrine-induced hyponatremia and original studies, randomized control trials, case controls, cohort studies and studies in English language. This study excludes the pediatric population and animal studies. For information sources, several electronic databases, including EMBASE, Pubmed, SCOPUS and Cochrane, will be searched. No ethical approval is required since the study does not involve human subject participation. However, the study findings will be applied for dissemination at scientific conferences and the manuscript will be submitted for publication to a reputable peer review journal. The research protocol is registered with PROSPERO registration No. CRD42023391854 and is available from: https://www.crd.york.ac.uk/prospero/display_record.php?ID=CRD42023391854.