Background: Children receiving stimulants for attention deficit hyperactivity disorder (ADHD) frequently present to pediatric endocrinology clinics for evaluation and treatment of growth disorders. The worldwide prevalence of stimulant use in children with ADHD also receiving recombinant human growth hormone (rhGH) and the impact on response to rhGH are unknown.
Methods: Data on children enrolled in the KIGS® (Pfizer International Growth Study) registry were evaluated for the associated diagnosis of ADHD prior to initiation of Genotropin® rhGH. Concomitant stimulant medications and auxological information were captured. Response to rhGH was evaluated using established growth prediction models.
Results: The prevalence of ADHD in KIGS was 2.3% (1,748/75,251), with stimulants used in 1.8% (1,326/75,251). Children with idiopathic growth hormone deficiency (IGHD) who received stimulants grew significantly less (1.1 cm) in the first year of rhGH therapy than expected for rhGH-treated non-ADHD IGHD children. After one year of rhGH, idiopathic short stature (ISS) children with ADHD were significantly shorter [0.74 cm (with stimulants) and 0.69 cm (without stimulants)] than non-ADHD ISS children.
Conclusions: We demonstrated an impaired response to rhGH in IGHD and ISS children with ADHD. Our findings suggest that the ADHD phenotype, alone or in conjunction with stimulant therapy, may impair the short-term growth response to rhGH.