Growth Hormone and Thyroid Function in Children With Attention Deficit Hyperactivity Disorder Undergoing Drug Therapy

Abstract

Context: The trends in hormone indices of children with attention deficit hyperactivity disorder (ADHD) who received long-term medication treatment remains controversial.

Objective: This prospective study aimed to examine the changes in the growth hormone and thyroid hormone systems among children with ADHD undergoing various medication treatments.

Methods: In total, 118 children who were diagnosed with ADHD and were drug-naive were observed naturalistically over 12 months. Of them, 22 did not receive any medication, while 39, 40, and 17 were treated with low doses of short-acting methylphenidate (MPH) (14 ± 6.7 mg/day), osmotic-release oral system (OROS) long-acting MPH (32 ± 9.6 mg/day), and atomoxetine (29.2 ± 9.7 mg/day), respectively. Blood samples were obtained at both the baseline and the endpoint (month 12) to measure serum levels of insulin-like growth factor 1 (IGF-1), IGF binding protein 3 (IGFBP-3), prolactin, thyroid-stimulating hormone (TSH), triiodothyronine (T3), thyroxine (T4), and free T4.

Results: Trends for IGF-1, IGFBP-3, prolactin, TSH, T3, T4, and free T4 levels were similar among the 4 groups. Changes in serum levels of IGF-1 were positively correlated with changes in height and weight of all the children with ADHD. However, patients who received MPH treatment had less body weight gain than the nonmedicated group. The ratio of MPH doses to body weight was inversely correlated with the increment in height.

Conclusion: There were no changes in thyroid or growth hormones associated with the low doses of ADHD medications used in this study within 1 year's duration. Nonetheless, patients' growth and the appropriateness of drug dosage should be closely monitored.

Keywords: ADHD; endocrinology; growth hormones; prospective study; stimulants; thyroid.