Correlation Between Vitamin D And Symptoms Severity Of POTS Children And Its RAAS

Objective: To investigate the levels of 25-hydroxyvitamin D [25（OH）D],reninangiotensin-aldosterone-system（RAAS）and their symptom scores in children with postural tachycardia syndrome（POTS）,and to explore the correlation between serum25（OH）D levels and RAAS and its symptom severity in children with POTS,in order to find a new target for the pathogenesis and treatment of children with POTS.Methods: This study enrolled 113 children with POTS who presented to the Pediatric Cardiovascular Department of the Second Hospital of Lanzhou University between December 2019 and September 2021 with symptoms of orthostatic intolerance such as unexplained dizziness or（syncope）and were diagnosed with POTS by upright test/head-up tilt table test（HUT/HUTT）.Another 130 healthy children who visited the Outpatient Department of Child Health of the Second Hospital of Lanzhou University for health examination during the same period and had no discomfort symptoms were selected as the control group.The general data of all children were collected,and their fasting serum 25（OH）D levels were measured;and the concentrations of various indicators of the RAAS system（AI basis,AI provocation,AII basis,AII provocation,ALD basis,ALD provocation,PRA basis,PRA provocation）at the basic and provocation levels of the children in the POTS group were measured;at the same time,the children in the POTS group were scored for the severity of symptoms,including a total of 10 symptoms: syncope,tremor in hands,nausea,palpitation,headache,profuse perspiration,blurred vision,chest discomfort,lightheadedness,and concentration difficulties.The correlation between serum vitamin D levels and symptom scores of POTS children and its RAAS was analyzed.Results:（1）The serum 25（OH）D level in the POTS group was significantly lower than that in the control group（12.18 ± 3.93 vs.18.39 ± 4.12 ng/ml,P < 0.001）.the vitamin D deficiency rate in the POTS group was 76.1 %（86）,and that in the control group was 24.6 %（32）,with significant difference（P < 0.001）.（2）The total symptom scores of the vitamin D deficiency group,vitamin D insufficient group,and vitamin D sufficient group of the POTS children were different,and the symptom scores of the vitamin D deficiency group were significantly higher than those of the vitamin D insufficient group and vitamin D sufficient group,difference had a statistical significance（12 ± 3 vs.10 ± 2,12 ± 3 vs.7 ± 2,P < 0.05）;The distribution of syncope,blurred vision,and palpitation symptoms in the vitamin D deficiency group,vitamin D insufficient group,and vitamin D sufficient group of the POTS children were different,and the syncope symptom of the vitamin D deficiency group were significantly higher than those of the vitamin D insufficient group and vitamin D sufficient group,difference had a statistical significance[2（1.5,3）vs 0（0,1）,P<0.05;2（1.5,3）vs 0（0,0.5）,P<0.05];the blurred vision symptom of the vitamin D deficiency group were significantly higher than of the vitamin D insufficient group,had a statistical significance[2（0,3）vs0（0,2.5）,P<0.05];the palpitation symptom of the vitamin D deficiency group were significantly higher than of the vitamin D sufficient group,had a statistical significance [3（2,3）vs 2（0,2）,P<0.05)].（3）Pearson correlation analysis showed that serum 25（OH）D levels were negatively correlated with symptom scores in the POTS group（r =-0.542,P < 0.001）;（4）Spearman correlation analysis showed that serum 25（OH）D levels were negatively correlated with PRA provocation,Ang II basal,and Ang II provocation in the POTS group,however,there was no correlation with the PRA basis,Ang I basis and provocation,ALD basis and provocation.Conclusion: Children and adolescents with POTS have significant vitamin D deficiency,and the severity of symptoms is aggravated with the decrease of vitamin D level,in which syncope and palpitation、blurred vision are more likely to occur in children with vitamin D deficiency;Vitamin D deficiency may be involved in the pathogenesis of POTS in children by regulating the RAAS system,resulting in increased serum renin provocation,Ang II basal and provocation levels.