Research on Changes of Plasma 5-hydroxytryptamine, Prolactin and Cortisol in Children with Vasovagal Syncope

Objective: To investigate the dynamic changes of 5-hydroxytryptamine (5-HT) and its related factors in children with vasovagal syncope (VVS).
Methods: From January 2017 to February 2019, thirty-two children diagnosed as VVS in Children`s Hospital-Capital Institute of Pediatrics were recruited as case group, while twenty healthy children were recruited as control group. All subjects accepted the head-up tilt test. Blood samples were collected before HUTT and at the time of syncope, presyncope or at the end of HUTT. The levels of plasma 5-HT, prolactin (PRL) and cortisol (Cor) were measured and compared.

Results: 1. There were no significant differences in plasma 5-HT levels, plasma PRL and Cor levels between the two groups in the baseline. 2. Comparison of plasma 5-HT, PRL and Cor between VVS group and control group after HUTT: (1) There was no significant difference in plasma 5-HT levels between VVS group and control group .(2) The mean plasma PRL level of VVS group was significantly higher (123.36±7.69mIU/ml vs 116.16±13.04mIU/ml, t=2.51, P=0.02)，so as to the mean plasma Cor level of VVS group(90.82±10.09ng/ml vs 80.47±8.47ng/ml，t=3.82, P=0.00）. 3. Comparison of plasma 5-HT, PRL and Cor levels in the baseline and HUTT-positive moment in VVS group: (1) There was no significant difference in plasma 5-HT levels between the baseline and HUTT-positive moment. (2) The mean plasma PRL level and Cor level of the baseline were significantly higher than that of HUTT-positive moment in VVS group .

Conclusion: In children with VVS, plasma 5-HT had no significant changes at syncope episodes, but plasma PRL and Cor levels increased significantly, indicating that central 5-HT system may be involved in the pathogenesis of VVS in children.