Objective: To investigate if the low
sodium intake is associated with the plasma
carnitine and
acylcarnitine profile in children with
vasovagal syncope (VVS). Materials and Methods: Twenty-six children suffering from VVS were recruited in the present study and divided into a group of low urinary
sodium excretion or a group of normal urinary
sodium excretion according to the excretion of 24-h urinary
sodium <3 or 3-6 g, respectively. The excretion of 24-h urinary
sodium was detected with
ion-selective electrode approach. Plasma
carnitine and
acylcarnitine concentrations were measured with tandem mass spectrometry. Each participant completed the head-up tilt test. The demographics, clinical characteristics, hemodynamic parameters and plasma
carnitine and
acylcarnitine concentrations were compared between the two groups. A bivariate correlation between plasma
acylcarnitine profiles and the excretion of 24-h urinary
sodium was conducted with Spearman's correlation coefficients. Results: Of the enrolled VVS patients, 14 patients were assigned to the group of low urinary
sodium excretion and the remaining 12 patients were assigned to the group of normal urinary
sodium excretion. Symptoms of
fatigue were more prevalent in the group of low urinary
sodium excretion than in the group of normal urinary
sodium excretion (p = 0.009). Aside from
fatigue, no other differences in the demographics, clinical characteristics or hemodynamic parameters during the head-up tilt test were found between the two groups (p > 0.05). Concentrations of plasma
tiglylcarnitine (C5:1), hydroxyhexadecanoylcarnitine (C16OH), hydroxyoctadecanoylcarnitine (C18OH), and
carnitine C22 were significantly higher in the group of low urinary
sodium excretion than in the group of normal urinary
sodium excretion (all p-values = 0.048); moreover, they were all negatively correlated with 24-h urinary
sodium levels (all p-values = 0.016). There were no differences between the two groups in other acylcarnitines or free
carnitine. Conclusions: Reduced excretion of 24-h urinary
sodium is associated with a disturbed plasma
acylcarnitine profile in children with VVS. The findings suggest that restricted
sodium intake-induced disturbance of plasma acylcarnitines and related cellular energy metabolism might be involved in the pathogenesis of VVS in children.