Ferritin and Iron Levels in Children with Autistic Disorder

Background:

Iron is a component of many enzymes involved in neurotransmitter synthesis including tryptophan hydroxylase (serotonin) and tyrosine hydroxylase (noradrenalin and dopamine). Brain monoamine neurotransmitter systems may be affected by iron deficiency due to decreased activity of associated enzymes.

Low ferritin levels are a sign of iron deficiency and an early precursor of iron-deficiency anemia. Recent studies showed low ferritin levels in subjects with restless legs syndrome, attention deficit hyperactivity disorder and Tourette’s syndrome. It was speculated that iron deficiency might contribute to the pathophysiology of RLS, ADHD and TS via its impact on the metabolism of dopamine and other catecholamines which have been involved in the pathophysiology these disorders.

Objectives:

High prevalence of low serum ferritin has been reported in children with autism spectrum disorder before. The aim of this study was to investigate and compare the iron status of children with autistic disorder (AD) in different age groups.

Methods:

The study group consisted of 112 children and adolescents (age 3–17; mean ± SD = 9.9 ± 2.8 years) who met DSM-IV diagnostic criteria for AD by clinical assessment. All patients were recruited from Bakırköy State Hospital for Mental Health and Neurological Disorders, Child Psychiatry Clinic during May 2008 – October 2009. The clinical evaluation of all subjects was made by two experienced child psychiatrists independently. Parents and children were interviewed about children’s’ medical history; children with any diagnosed genetic, metabolic, or neurological disorders were excluded from the study. Children with dietary restrictions also were excluded.

Results:

The mean serum ferritin level was 26.2 ± 4.7  ng/ml. Children in preschooler group had significantly lower ferritin levels than school-age and adolescent groups, 20.7, 28.3, 34.9, respectively. The mean iron level was 73.2 ± 5.1. Children in preschool group had lower iron levels than other two groups, but this was not significant. Iron deficiency was detected in 19.5 % of the total sample; this was 26 % in preschoolers, 18 % and 12 % in school aged and adolescent groups.

Conclusions:

This current study confirmed the high prevalence of low ferritin levels in autism, in parallel with previous reports. The reason for lower ferritin levels in children with autistic disorder is unclear. Autism and iron deficiency could be linked by a common underlying genetic mechanism that has not been identified yet. Alternatively, because iron is involved in brain monoamine systems, iron may influence autism through its effects on monoamine-dependent neurotransmission. As intestinal dysfunction was described in autism, impaired absorption might be a possible cause of iron deficiency. However no subjects in our study group had evidence of intestinal malabsorption. Finally, as it is the case for most iron-deficient children in the general population, iron deficiency in autism may be a result of reduced dietary iron intake.