Objective: Attention deficit hyperactivity disorder (ADHD) is a commonly diagnosed psychiatric disorder in the childhood and it has been suggested that both environmental and genetic factors take place in the etiology. Therefore, it is important to determine metabolic and endocrine abnormalities that accompanies with ADHD in order to understand the pathophysiology of ADHD and in order to develop new treatment strategies. The aims of this study were to evaluate serum TSH, vitamin B12, folate abnormalities and iron deficiency in children with ADHD and investigate the association between iron deficiency and subtypes of ADHD.
Methods: Patients who applied to Gazi University Medicine Faculty Child and Adolescent Psychiatry Out-Patient Clinic diagnosed with ADHD as per DSM-IV-TR diagnoses criteria between time period May 2012-Feb 2013 were involved in this study. Records and laboratory results of patients were retrospectively collected and evaluated.
Results: This study included 199 children age between of 6-16 years (mean age 9.43±2.2) with ADHD whose 87.2% were boys (n=174) and 12.6% of children (n=25) were girls. 80.9% of children (n=161) were combined type ADHD while 19.1% of children (n=38) were predominantly inattentive type. 52.8% of children (n=105) had iron deficiency while 2.5% of children (n=5) had subclinical hypothyroidism and 3% of children (n=6) had vitamin B12 deficiency. It was determined that 59% of children with combined type ADHD had iron deficiency while in children with predominantly inattentive type rate was 26.3%. There was statistically significant relation between iron deficiency and subtypes of ADHD (p<0.001).
Conclusion: Iron deficiency and thyroid function abnormalities which are known to have important roles on neurocognitive functions are frequently accompanies with ADHD in childhood. In addition, accompanying iron deficiency affects the clinical status of the ADHD. In resent literature several studies published about the relationship between iron deficiency and subtypes of ADHD but results are inconsistent. According to results of this study, iron deficiency is more frequent in children with combined type ADHD with respect to predominantly inattentive type; it is suggested that iron metabolism considered to have more important effects on symptoms related with hyperactivity and impulsivity.