Low-Dose ADHD Medications Not Associated With Changes in Thyroid and Growth Hormones in Children

Use of low-dose attention-deficit/hyperactivity disorder (ADHD) medications for 1 year was not found to be associated with changes in thyroid or growth hormone levels among children aged 6 to 12 years, according to the results of a study reported in the Journal of Clinical Endocrinology & Metabolism.

Investigator conducted the prospective study to determine whether 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 had differential trends in children with ADHD who were treated with different medications.

Eligible participants had a clinical diagnosis of ADHD, were aged 6 to 12 years, were drug-naive, and did not have a history of a comorbid neurodevelopmental or psychiatric disorder.

A total of 118 patients were assessed at baseline and month 12. Among the cohort, 22 participants (18.6%; 72.7% male) did not receive any medication (nonmedicated group), 39 (33.1%; 76.9% male) received short-acting methylphenidate (IR-MPH), 40 (33.9%; 82.5% male) received long-acting MPH (OROS-MPH), and 17 (14.4%; 82.4% male) received atomoxetine.

At 12 months, the serum levels of IGF-1 were significantly increased in the nonmedicated group (Wilcoxon signed-rank test=2.386; P =.017), the IR-MPH group (statistic=2.358, P =.018), and the OROS-MPH group (statistic=3.168; P =.002). Levels of IGFBP-3 were significantly increased in the OROS-MPH group (statistic=2.079; P =.038) and the atomoxetine group (statistic=2.864, P =.004).

IGF-1 standard deviation (SD) scores in the OROS-MPH group increased significantly (statistic=2.567, P =.010), but no significant changes were found in the nonmedicated group, the IR-MPH group, or the atomoxetine group. No significant changes in IGFBP-3-SD scores were noted among the 4 groups.

Changes in serum IGF-1 levels were positively correlated with the changes in height (r=0.448, P <.001) and weight (r=0.395, P <.001) for all participants after 12 months. Prolactin levels and thyroid function indices (T4, free T4, T3, and TSH) did not change significantly among the 4 groups.

Increments in body weight in the IR-MPH group (4.2±1.7 kg) and OROS-MPH group (4.1±1.6 kg) were less than those reported in the nonmedicated group (5.6±1.8 kg) and the atomoxetine group (4.7±2.6 kg; statistic=9.285, P =.026). Also, increments in body mass index (BMI) in the IR-MPH group (0.8±0.8 kg/m²) and the OROS-MPH group (0.5±0.7 kg/m²) were less than those reported in the nonmedicated group (1.3±0.7 kg/m²) and the atomoxetine group (1.0±1.1 kg/m²; statistic=14.678, P =.002).

Although changes in height-SD were not significantly different among the 4 groups (statistic=4.307, P =.230), BMI-SD changes were significantly different among the groups (statistic=17.69, P =.001).

ADHD-Rating Scale inattention scores and hyperactivity/impulsivity scores were found to be consistently decreased in the groups.

The researchers noted that their findings regarding minimal changes in growth and hormone measures could be attributed to the low doses of ADHD drugs administered. Also, adherence to treatment, drug holiday, and serum concentrations were not considered, and allocation toward treatment was not randomized.

“The results in this study provide new information for clinicians as low doses of ADHD medications exhibited no detrimental effect on children’s growth and hormone systems in a year’s duration,” stated the study authors. “Nonetheless, patients’ growth and the appropriateness of drug dosage should be closely monitored among ADHD patients with long-term pharmacotherapy.”

Reference

Wang L-J, Huang Y-H, Chou W-J, Lee S-Y. Growth hormone and thyroid function in children with attention deficit/hyperactivity disorder undergoing drug therapy. J Clin Endocrinol Metab. Published online March 9, 2022. doi:10.1210/clinem/dgac139