Low iron storage in children with tilt positive neurally mediated syncope

Background: The mechanisms under neurally mediated syncope (NMS) are not fully understood. This study aimed to assess the level of storage iron in children with different hemodynamic patterns in head-up tilt test. Methods: Altogether 210 children (11.31 +/- 2.49 years) with syncope or pre-syncope treated between May 2008 and September 2010 were studied prospectively. Following history taking and physical examination, their levels of hemoglobin (Hb), hematocrit (Hct) and serum ferritin were measured. Results: In the 210 children, 162 (77.1%) had NMS and 48 (22.9%) had syncope due to other causes. In the 162 children with NMS, 98 children were subjected to positive tilt test. The level of serum ferritin was significantly lower in the 98 children with NMS (P<0.001). The comparison of levels of Hb, Hct and mean cell volume (MCV) displayed no significant difference between the two groups. Reduced iron storage (serum ferritin <25 ng/mL) was found to be more prevalent in children with NMS (63% vs. 20%, P<0.001). Prevalence of iron deficiency was also significantly higher in children with NMS than in children with syncope due to other causes (27% vs. 6%, P=0.003). Conclusions: In head-up tilt test positive children with NMS, the level of serum ferritin should be evaluated. Low storage iron may be one of the underlying mechanisms of NMS.