Background: Methylphenidate (MPH) is generally considered to be first-line treatment for the core symptoms of Attention Deficit Hyperactivity Disorder (ADHD). Long-term administration of MPH in childhood may have adverse effects on growth.
Objective: To determine the effect of long-term, short-acting MPH medication on growth.
Material and method: A retrospective descriptive study was employed by gathering the data of patients who were diagnosed as ADHD by child psychiatrists at the child and adolescent clinic, Queen Sirikit National Institute of Child Health. Subjects were patients received the first dose of short-acting methylphenidate from January 1st 2000 to December 31st 2007 and continued medication for at least 1 year. Data about height and weight were reviewed at the beginning of short-acting MPH medication, 6 months (mo), 1 yr, 2 yr, 3 yr, 4 yr, 5 yr, 6 yr and 7 yr interval. Collecting data was interpreted with INMU-Nutri Stat software program. Paired t-test was used to compare Z score of height and weight at different time points.
Results: There were 96 cases in the present study; the ratio of male to female was 3.6: 1. The first dose of short-acting methylphenidate was started at an average age of 8.62 +/- 1.70 years. Average drug dose ranged from 0.41-0.49 mg/kg/day. The data evaluated at 6 mo, 1 year 2 years, 3 years, 4 years and 5 years after drug use found that weight was not affected. Height decreased at 6 mo. after drug use (p < 0.05) but long-term treatment was not statistically significant.
Conclusion: Prolonged medication with short-acting MPH has shown to have minimal impact on height only at the first 6 months; however, catch up growth was detected during adolescent period.