Response to growth hormone in attention deficit hyperactivity disorder: effects of methylphenidate and pemoline therapy.

OBJECTIVE

To determine whether treatment of attention deficit hyperactivity disorder (ADHD) with methylphenidate hydrochloride or pemoline diminishes the response to growth hormone (GH) therapy in patients with idiopathic GH deficiency (IGHD) or idiopathic short stature (ISS).

METHODS

The National Cooperative Growth Study database was used to identify patients between 3 and 20 years of age with IGHD or ISS and those within these groups who were treated with methylphenidate or pemoline for ADHD. Their growth in response to GH treatment (change in height standard deviation score [SDS]) was compared with that of patients with IGHD or ISS who were not treated for ADHD, by using a stepwise multiple regression analysis.

RESULTS

In the IGHD cohort, there were 184 patients who were being treated for ADHD and 2313 who were not. In the ISS cohort there were 117 patients who were being treated for ADHD and 1283 who were not. There was a higher percentage of males being treated for ADHD in both cohorts. In the IGHD cohort, the change in height SDS was positively associated with the number of years of GH treatment, parents' heights, body mass index, and GH injection schedule, and was negatively associated with height SDS at the initiation of GH therapy, age, and maximum stimulated GH level. The use of methylphenidate or pemoline had a negative effect on the change in height SDS, but the magnitude of the effect was small. Similar effects were noted in the ISS cohort, but body mass index and the use of methylphenidate or pemoline had no effect on the change in height SDS.

CONCLUSIONS

Concurrent ADHD therapy is associated with a slight decrease in the change in height SDS during GH treatment in patients with IGHD but not in those with ISS. Even in IGHD, the magnitude of the effect is small and should not deter the use of such concurrent therapy.