Relationship of serum ferritin level and tic severity in children with Tourette syndrome

Tics can be considered hyperkinetic movements akin to restless leg syndrome (RLS). Drawing the analogy of iron deficiency as an etiology of RLS, it is conceivable that iron deficiency may underlie or worsen tics in Tourette syndrome (TS). The purpose of this study was to evaluate the relationship between serum ferritin levels and tic severity, as well as consequent impact on life, in children with TS.

Children <18 years, diagnosed with TS during 2009-2015, were reviewed. Only those with serum ferritin testing were included. The following data were collected: tic severity, impact on life, medication, comorbidities, blood count, and serum ferritin at diagnosis and follow-up.

In fifty-seven patients, M:F = 2:1, serum ferritin was 48.0 ± 33.28 ng/mL, tic severity score 2.3 ± 0.80, impact on life score 2.2 ± 0.93, and composite score 4.57 ± 1.6. Serum ferritin was not influenced by comorbid obsessive compulsive disorder (OCD), attention deficit hyperactive disorder (ADHD), or anxiety (P > 0.16). Thirty-eight percent with low serum ferritin (≤50 ng/mL) (n = 37) had severe tics (>5 composite score), compared with 25% in normal ferritin group (n = 20). Over 6-12 months, tic severity score improved in both iron treated groups, deficient (2.70 to 1.90) and sufficient (2.40 to 1.95), whereas tics worsened or remained the same when not treated with iron.

Our data suggest iron deficiency may be associated with more severe tics with higher impact on TS children, independent of the presence of OCD, ADHD, or anxiety. Iron supplementation showed a trend towards improvement of tic severity upon follow-up. We suggest a double-blind, placebo-controlled prospective study to reach a definite conclusion.