Antipituitary antibodies recognizing growth hormone (GH)-producing cells in children with idiopathic GH deficiency and in children with idiopathic short stature.

Antipituitary antibodies (APA) recognizing GH-secreting cells may indicate an autoimmune pituitary involvement in adults with idiopathic GH deficiency (IGHD). We aimed 1) to investigate the presence of APA in prepubertal children with IGHD or idiopathic short stature (ISS), identifying the pituitary hormone-producing cells targeted by APA; and 2) to verify whether in patients with ISS the presence of APA could predict the development of GHD. We performed a cross-sectional and partially longitudinal cohort study. The study was performed at the Endocrinology Unit and Pediatric Unit of the Second University and University Federico II of Naples, respectively. Twenty-six children with IGHD (group 1), 60 children with ISS (group 2), 33 children with GHD caused by lesions/abnormalities of the hypothalamus or pituitary (group 3), and 40 controls participated in the study. Nineteen children of group 2 were reevaluated after 2 yr. IGF-I levels, GH secretion, and APA (by indirect immunofluorescence) were evaluated in all participants. At study entry, APA recognizing GH-producing cells were detected in seven of 26 children in group 1 and in 14 of 60 in group 2. Two years later, all eight initially APA-positive and all 11 APA-negative of the 19 reevaluated patients persisted positive and negative, respectively. The reevaluation of GH secretion in these patients revealed the development of GHD in all but one of the APA-positive children but in none of the APA-negative ones. IGHD in children can be frequently associated with APA targeting GH-secreting cells; thus, the detection of APA in children with ISS could identify those prone to develop GHD.