Inclusion Criteria:  Children diagnosed with POTS ; Compliance with the diagnostic guidelines for Syncope in children (2016 edition) and 2018 syncope in children and adolescents in the cardiovascular group of the Society of Pediatrics, Chinese Medical Association The diagnostic criteria of Oi in the Diagnostic and therapeutic guidelines.  Exclusion Criteria:  Taken 3 months prior to admission Vitamin D or hormone drugs; Heart, brain, nerves, metabolism, blood and other apparatus Syncope or aura of syncope caused by a qualitative disease;