IGHE and attention deficit-hyperactivity disorder: Although these points were situated in the subclinical (normal) range, logistic regression models indicated that Hb < 12.6 g/dL, 5-HT < 113.57 ng/mL, IgE > 367 KU/L, and eosinophil >5.85% were all significantly associated with an increased ADHD risk (Table 4).