Risk factors and causes of hyponatremia in patients after radiotherapy for head and neck cancer:A retrospective study

Background:Hyponatremia is the most frequently encountered electrolyte abnormality which is caused by kinds of reasons including kidney,metabolic and central nervous system diseases.The adverse effects of hyponatremia include but not limit to cerebral edema and seizures,which often aggravate neurological damage.Therefore,early diagnosis and intervention would reduce the risk of adverse effects of hyponatremia.Objective:To investigate the differences between patients with or without hyponatremia after radiotherapy for head and neck cancer,and to explore the risk factors and causes of hyponatremia.Methods:Patients who aged over 18 years old and underwent radiotherapy for head and neck cancer were collected from Department of Neurology,Sun Yat-Sen Memorial Hospital from January 2012 to July 2018.The comorbidities of patients and demographic and serological data were retrospectively collected to investigate the causes and risk factors of hyponatremia in these patients.Differences of the length of hospital stay and the cognitive function between patients with and without hyponatremia were analyzed.Results:In this study,798 patients were reviewed.The incidence of hyponatremia was 17.9%.Risk factors of hyponatremia included age(OR 1.05,95%CI 1.03–1.07,P<0.001),gender(OR 0.62,95%CI 0.39–0.99,P=0.046),medical history of hypothyroidism(OR 2.42,95%CI 1.26–4.09,P紏0.006),adrenal insufficiency(OR 15.61,95%CI 2.73–89.07,P=0.002)or dysphagia(OR 1.81,95%CI 1.24–2.65,P=0.002).The most common cause of hyponatremia was cerebral salt-wasting syndrome(CSWS)(32.9%).The insufficient intake due to dysphagia(29.4%),and hypothyroidism(13.3%)were also common in these patients.Clinically,hyponatremia resulted in the prolonged hospitalization time.Conclusion:Hyponatremia would be common in patients who underwent radiotherapy for head and neck cancer.The importance of distinguishing the etiology of hyponatremia is addressed.