[Efficacy of letrozole in treatment of male adolescents with idiopathic short stature]

ObjectiveTo evaluate the efficacy and safety of aromatase inhibitor letrozole in treatment of male adolescents with idiopathic short stature (ISS). MethodSeventy five boys with height less than 2 standard deviation (SD) below the mean who had entered puberty were enrolled in our study from 2004 to 2017, in the Pediatric Department of the First Affiliated Hospital, Sun Yat-Sen University. Among 75 patients, 28 in letrozole group received letrozole and spironolactone, 30 in gonadotrophin releasing hormone analogue (GnRHa) group received GnRHa injection and 17 had no intervention. Height velocity (HV), increment of bone age/chronological age (ΔBA/ΔCA), the final adult height (FAH) were compared among groups and the safety of letrozole treatment was evaluated. ResultsHV maintained faster during letrozole treatment when compared with other groups. HV during GnRHa treatment showed slightly decline in the first 6 months, but decreased remarkably after 6 months, and was significantly lower than that in letrozole group ( P < 0.05). The maturation of BA slowed down in both letrozole and GnRHa groups. But the ΔBA/ΔCA in letrozole group during the first and the second year of treatment were significantly higher (0.67±0.09, 0.50±0.15, respectively) when compared with GnRHa group (0.59±0.16, 0.44±0.13, respectively) ( t=2.78 and 2.20, all P < 0.05). FAH in letrozole group and GnRHa group were (170±4) cm and (170±6)cm, there was no significant differences between the two groups ( P>0.05), and both were higher than that in no intervention group (162±4 cm, P < 0.01). After 6 months of letrozole treatment, testicular volumes and serum testerone levels increased; 39.2% (11/28) boys had clinical manifestations of hyperandrogenemia, and 82.1% (23/28) boys had decreased serum high-density lipoprotein (HDL) levels. Serum levels of HDL and testerone returned normal and the hyperandrogenemia disappeared after the cessation of letrozole treatment. No significant changes in serum triglyceride, serum low-density lipoprotein (LDL), fating serum levels of insulin and glucose, HOMA-IR were observed. No abnormal liver function, myalgia, scoliosis or aggravations of scoliosis was found. ConclusionsLong term letrozole therapy during puberty in boys with ISS can delay bone maturation without significant decrease of linear growth, and thus can improve the final adult height. No severe adverse reactions were found.