Hyponatremia is a potential predictor of progression in radiation-induced brain necrosis: a retrospective study

BACKGROUND: To investigate the prognostic value of hyponatremia, defined as serum sodium level < 135 mEq/L, in radiation-induced brain necrosis (RN) patients. METHODS: We performed a retrospective analysis of the RN patients (The patients included in our study had a history of primary cancers including nasopharyngeal carcinoma/glioma/oral cancer and received radiotherapy previously and then were diagnosed with RN) treated in Sun yat-sen Memorial Hospital from January 2013 to August 2015. Patients without cranial magnetic resonance imaging (MRI) scan and serum sodium data were excluded. Progression was identified when the increase of edema area ≥ 25% on the MRI taken in six months comparing with those taken at the baseline. Factors that might associate with prognosis of RN were collected. Multivariable logistic regression analyses were used to identify potential predictors. RESULTS: We total included 135 patients, 32 (23.7%) of them with hyponatremia and 36 (26.7%) with RN progression. Percentage of progression was roughly three fold in hyponatremia patients compared with nonhyponatremia patients (53.1% versus 18.4%), translating into a 5-fold increased odds ratio (P < 0.001). Multivariable analyses identified hyponatremia as a potential predictor of progression (OR, 4.82; 95% CI [1.94–11.94]; P = 0.001). CONCLUSIONS: Hyponatremia was identified as a potential predictor for the progression of patients with RN. Hyponatremia management in patients with RN should be paid much more concern in clinical practice.