Abstract: Background：Cyclic vomiting syndrome (CVS) is a functional gastrointestinal disorder. There is no literature report on the association between CVS and renin angiotensin aldosterone system (RAAS). Objective： To explore the characteristics of changes in RAAS indicators and their influencing factors in children with CVS. Design：A case-control study. Methods：Children diagnosed with CVS for the first time and undergoing supine RAAS system examination with blood sampling during non-attack period were included in the pediatric department of Beijing Tsinghua Changgung Hospital from January 2022 to May 2024. According to the RAASResults：, they were divided into normal and abnormal groups, and their age of onset, age of admission, gender, height, weight, admission blood pressure, average duration of episodes, average daily vomiting frequency, RAAS levels, electrolytes, cortisol, and ACTH were collected for univariate and multivariate analysis. Main outcome measures：Possible factors influencing the normal and abnormal outcomes of RAAS. Results：A total of 105 cases of CVS were included in this study, including 49 cases (46.7%) in the normal RAAS group and 56 cases in the abnormal RAAS group. Among them, 39 cases (69.6%) had elevated renin concentration, 28 cases (50.0%) had elevated angiotensin II concentration, and 28 cases (50.0%) had elevated aldosterone concentration. There were statistically significant differences (P<0.05) in admission age, onset age, diastolic blood pressure, and blood potassium between the two groups. Binary logistic regression analysis showed that admission age was a factor affecting RAAS abnormalities, and the younger the age, the more likely RAAS abnormalities were to occur. Conclusion：RAAS abnormalities were present in 53.3% of children with CVS, and younger age was identified as the primary influencing factor.

Key words: Cyclic vomiting syndrome, Children, Renin angiotensin aldosterone system