Low Iron Storage in Children and Adolescents with Neurally Mediated Syncope

Objective

To investigate whether neurally mediated syncope (NMS) is associated with low iron storage or serum ferritin (SF).

Study design

206 children evaluated between 2000 and 2004 for probable syncope at a tertiary care Pediatric Neurology Clinic were included in a retrospective study. Serum ferritin (SF), iron, total iron binding capacity, and hemoglobin were measured prospectively after initial history taking and physical examination, along with other diagnostic testing. We defined iron deficiency (ID) as SF <12 μg/L, and low iron storage as SF ≤25 μg/L.

Results

Among 106 included patients with syncope, 71 had NMS and 35 had other causes of syncope. Patients with NMS, when compared with those with other causes of syncope, had a higher prevalence of low iron storage (57% vs 17%, P < .001) and lower mean values of SF (27 vs 46 μg/L, P < .001), transferrin saturation (23 vs 31 %, P < .01), and hemoglobin (13.3 vs 14 g/dL, P < .05). Only patients with NMS had ID (15%), anemia (11%), or ID with anemia (7%).

Conclusions

Low iron storage or serum ferritin is associated with NMS and is a potentially pathophysiologic factor in NMS.

Abbreviations: Hb, Hemoglobin, Hct, Hematocrit, ID, Iron deficiency, NMS, Neurally mediated syncope, OH, Orthostatic hypotension, POTS, Postural orthostatic tachycardia syndrome, SF, Serum ferritin, TIBC, Total iron-binding capacity, TLOC, Transient loss of consciousness