GRF-induced GH response in attention-deficit hyperactivity disorder.

Attention-deficit hyperactivity disorder (ADHD) is a type of disruptive behavior of unknown etiology with a prevalence of 2.5-5% in school-age children. The useful evaluation of the GRF-induced GH response as a marker in some mental disorders led us to study the response of GH to the exogenous administration of GRF (1-29) NH2 (150 micrograms, i.v.) in ADHD children (N = 12, age = 7.78 +/- 1.66 years) and healthy children (N = 6; age = 8.73 +/- 2.24 years) in order to evaluate the functioning of the somatotropinergic system (GRF-SS-GH-SM axis) and using this neuroendocrine test as a potential diagnostic marker and/or a therapeutic predictor in ADHD. While controls (CS) showed a maximum GH response to GRF 15 min after injection (37.15 +/- 29.56 ng/ml; basal GH = 5.49 +/- 4.71 ng/ml), ADHD children (basal GH = 2.28 +/- 1.66 ng/ml) exhibited a lower response with a plateau from 15 (21.32 +/- 10.00 ng/ml) to 60 min (26.48 +/- 23.72 ng/ml). Serum GH levels at 90 (17.23 +/- 14.45 vs. 5.99 +/- 2.82 ng/ml, p less than 0.05) and 120 min (11.89 +/- 8.63 vs. 4.12 +/- 1.66 ng/ml, p less than 0.05) were significantly higher in ADHD than in CS. According to the GRF-induced GH response elicited in ADHD, two different populations of patients can be distinguished; one group with high response of GH (AUC = 3372.21 +/- 1127.61 ng.min/ml) and another group with a hyporeactive GH (AUC = 1567.46 +/- 726.0 ng.min/ml, p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)