Letter to the Editor: Testosterone priming increased growth hormone peak levels in the stimulation test and suppressed gonadotropin secretion in three Japanese adolescent boys

Abstract

Dear Editor, We read with interest the article by Sato et al., entitled “Testosterone priming increased growth hormone peak levels in the stimulation test and suppressed gonadotropin secretion in three adolescent Japanese boys” in Clinical Pediatric Endocrinology (1). GH responsiveness to the GH stimulation test (GHST) is attenuated during the period just before puberty; however, testosterone priming may prevent unnecessary GH treatment (2). We reported two adolescent boys with suspected severe GH deficiency (GHD) in whom GH response normalized after testosterone priming. Case 1: An 11-yr-old boy with reduced growth rate was diagnosed with severe GHD via GHST. A clonidine test and arginine test administered at another hospital revealed peak GH levels of 1.06 and 1.26 ng/mL, respectively. The patient’s height was 144.5 cm (–0.19 SD), and he weighed 83.5 kg. His serum IGF I and testosterone levels were 156 ng/mL (–1.5 SD) and 0.14 ng/mL, respectively. One week after testosterone priming with a 125 mg intramuscular injection, his peak GH levels, as measured by an insulin torelance test (ITT) and GH-releasing peptide-2 stimulation test, were 10.2 and 21.97 ng/mL, respectively. Moreover, his annual growth rate increased by 9 cm without GH replacement therapy. Case 2: A 13-yr-old boy with short stature was diagnosed with severe GHD via GHST. A clonidine test and arginine test revealed peak GH levels of 0.93 and 0.64 ng/mL, respectively. His height was 139.1 cm (–2.2 SD), and his weight was 41.5 kg. His serum IGF I and testosterone levels were 113 ng/mL (–2.3 SD) and 0.15 ng/mL, respectively. One week after testosterone priming, his peak GH levels, as measure by an ITT and arginine test, were 9.2 and 5.2 ng/mL, respectively. He is undergoing follow-up without GH replacement therapy. Results of our case studies show that testosterone priming improves GH responsiveness, even in cases of suspected severe GHD. Conflicts of interests The authors declare no conflicts of interest associated with this manuscript.