The Relationship Of BNP And The Diameter Of Inferior Vena Cava And The Disorder Of Water And Sodium Metabolism After Operation Of Tumors In The Hypothalamus Region

Background: Hypothalamus is an important part of human diencephalon,which is involved in the regulation of water and sodium metabolism,sleep-wake cycle,pituitary-endocrine function,feeding,body temperature and other important functions.Saleem SN et al.point out that the anterior boundary of the hypothalamus region extends from the anterior commissure to the optic chiasm and the lamina terminalis,the upper boundary is an imaginary line between the anterior commissure and the posterior commissure,the posterior boundary extends from the mamillary bodies to the posterior commissure,the lateral boundary of the hypothalamus region is the medial thalamus.The tumors that invade these areas are collectively referred to as tumors in the hypothalamus region regardless of their origin or pathological type.Because of its important location,the patients with tumors in the hypothalamus region will mostly have the symptoms of water and sodium metabolism disorders after surgery,such as diabetes insipidus,the syndrome of inappropriate secretion of antidiuretic hormone(SIADH),cerebral salt-wasting syndrome(CSWS),hypernatremia and hyponatremia.The specific causes of water and sodium metabolism disorders are not fully understood.There are mainly related to the secretion of antidiuretic hormone,natriuretic peptides and the effect of sympathetic nerve on kidney.Many studies have shown that brain natriuretic peptide(BNP),one of the natriuretic peptides,plays an important role in the disorder of water and sodium metabolism after brain injury.There is no effective and reliable laboratory testing method for differentiating SIADH and CSWS which causes hyponatremia.Although it can be distinguished in clinical work,it is easy to misdiagnose.The main difference between the two syndromes is blood volume,so assessing blood volume through the diameter of the inferior vena cava may be helpful for identifying the two syndromes.Objective: This study plans to investigate the changes of BNP,blood sodium,24h urine sodium,24 urine volume,blood volume and other factors before and after operation of patients with tumors in the hypothalamus region,analyze the relationship of BNP and the diameter of inferior vena cava and the disorders of water and sodium metabolism after operation of tumors in the hypothalamus region,find a reliable and effective laboratory testing method to distinguish CSWS and SIADH,so as to provide help for the diagnosis and treatment of the disorders of water and sodium metabolism after operation of tumors in the hypothalamus region.Methods:From December 2018 to May 2020,31 patients with tumors in the hypothalamus region(including 12 cases of craniopharyngioma,13 cases of upper sellar pituitary adenoma,5 cases of hypothalamic glioma,1 case of hypothalamic hamartoma)were selected fromNeurosurgery Department of Affiliated Hospital of Qingdao University.Blood BNP,blood electrolyte,24h urine electrolyte,24 urine volume and blood volume were measured on them before and after operation.The changes after and before operation of blood BNP,24h urine sodium,24h urine volume and the diameter of inferior vena cava were compared by means of Repeated Measures ANOVA.The differences of blood BNP,24h urine sodium,24h urine volume and the diameter of inferior vena cava among different groups were compared by t test or rank sum test according to the types of water and sodium metabolism disorders after operation of tumors in the hypothalamus region.The differences between CSWS and SIADH in blood BNP,24h urine sodium,24h urine volume and inferior vena cava diameter were statistically analyzed by t test or rank sum test.The correlations between 24h urine sodium,24h urine volume and BNP were analyzed by the Pearson Correlation Analysis.Results:In 31 patients with tumors in the hypothalamus region,10 patients developed hypernatremia,the incidence of hypernatremia was 32%.The mean occurrence time was2.50(2.00?3.75)days after operation.15 patients with hyponatremia,the incidence of hyponatremia was 48%,and the mean occurrence time was 6.00(5.00?6.75)days after operation.The occurrence time of hypernatremia was significantly earlier than that of hyponatremia,P<0.001.26 patients with diabetes insipidus,the incidence was 84%,mostly appeared in early 3 days after the operation.The diameters of the inferior vena cava were compared before and after the operation of patients with diabetes insipidus,the D-value was-2.70(-4.25?-1.03)mm.The other diameters of the inferior vena cava were compared before and after the operation of patients without diabetes insipidus,the D-value was-1.20(-2.68?-0.20)mm.The difference is statistically significant between the two D-values,P<0.001.The BNP,24 h urine sodium,24h urine volume,the diameters of the inferior vena cava after operation are significantly different compared with those before operation,P values were all less than 0.05,the differences were statistically significant.Hyponatremia group compared with non-hyponatremia group,BNP was only in the 4th,5th and 6th days after the operation significantly higher,P=0.020,P=0.014,P=0.016.There were no significant differences of 24h urine sodium volume and 24 h urine sodium concentration in this two groups,P values were all more than 0.05.Compared CSWS patients with SIADH patients,BNP,24h urine sodium volume,24 urine sodium concentration and 24 urine volume were significantly higher than SIADH patients,P values were all less than 0.001.The d-value of inferior vena cava diameter between post-operative and preoperative in CSWS patients was significantly smaller than SIADH patients,P<0.001.The correlation between 24h urine sodium volume,24h urine sodium concentration,24 urine volume and BNP after operation of tumors in the hypothalamus region showed,there was a significant correlation between 24 hour urinary sodium and BNP,P<0.001,the correlation coefficient was 0.479.The 24h urine sodium concentration was correlated with BNP,P<0.001,the correlation coefficient was 0.278.The 24h urine volume was correlated with BNP,P=0.002,the correlation coefficient was 0.226.Conclusion:1.BNP was involved in the metabolism of sodium water after operation of tumors in the hypothalamus region,and was an important factor that affecting the metabolism of sodium and water after operation of tumors in the hypothalamus region.2.There was a positive correlation between BNP and 24 hour urinary sodium excretion,all of them can be used as important indicators to diagnostic the CSWS and SIADH after operation of the tumors in the hypothalamus region.3.The measurement of the diameter of inferior vena cava by ultrasonography,which can therefore evaluate blood volume,can be used as a non-invasive and convenient clinical method for the diagnosis of water and sodium metabolic disorders after operation of tumors in the hypothalamus region.