Assessment of adenohypophysis function and ghrelin level in children with biologically inactive growth hormone syndrome

Abstract

Background. Mutations in the growth hormone (GH) gene cause various forms of biologically inactive growth hormone (BIGH) syndrome. Ghrelin potentiates the secretion of GH. Ade­nohypophysis hormones take part in human growth mechanisms. Insulin-like growth factor 1 (IGF-1) level is a criterion of GH activity. The purpose of the study was to assess the adenohypo­physis functions and to determine the role of ghrelin in patients with BIGH syndrome to optimize the diagnosis and treatment. Materials and methods. Anthropometric parameters were evalua­ted in 158 children with BIGH syndrome whose average age was 7.83 ± 1.23 years. The function of the adenohypophysis was evalua­ted accor­ding to the levels of somatotropin, thyroid-sti­mulating, adrenocorticotropic, luteinizing, follicle-stimulating hormone and their corresponding peripheral hormones, which were determined by radioimmunological methods and chemiluminescent immunoassay. A statistical analysis of the results was carried out. Results. The release of GH against the background of clonidine and insulin tests in patients with BIGH syndrome was higher than 10 ng/ml, the basal level of IGF-1 was significantly lower than the reference values. After a 4-day test for sensitivity to GH, the level of IGF-1 increased more than 2 times. Against the background of treatment with recombinant GH, serum thyroid-stimulating, adrenocorticotropic hormone, and cortisol indicators changed significantly, but their levels fluctuated within the reference values. Significant changes in ghrelin content were detected 120 minutes after falling asleep. Most children with BIGH syndrome had timely sexual development, precocious puberty was revealed in 19 children, the smallest was the group with delayed puberty (5 children). Gonadotropin-releasing hormone ana­logues were added to the GH treatment in case of unsatisfactory final growth. Conclusions. Normal/high levels of GH and reduced IGF-1 are characteristic of children with BIGH syndrome. In addition, these children have a significant increase in ghrelin in the first hours after falling asleep. The test for sensitivity to GH is a reliable diagnostic method. Thyroid and adrenal disorders were not found in patients with BIGH syndrome. Children with BIGH syndrome have normal sexual development with a tendency to precocious puberty. The simultaneous use of gonadotropin-releasing hormone analogues in combination with GH preparations significantly improves patients’ final growth.

Keywords

• biologically inactive growth hormone
• children
• short stature
• ghrelin
• adenohypophysis