Background: Data regarding the onset of puberty in children receiving mammalian target of rapamycin (mTOR) inhibitors are limited.
Methods: Kidney transplant patients aged <14 years were analyzed retrospectively to a maximum age of 18 years, with a minimal observation period of 1 year. Immunosuppression comprised (1) standard CNI-based regimen or (2) low-exposure mTOR inhibitor with reduced-exposure CNI, initiated either de novo or in the maintenance phase.
Results: Of 108 children analyzed, 67 received an mTOR inhibitor (56 everolimus, 11 sirolimus) and 41 did not. The age at which girls reached Tanner stage P2 was similar with mTOR inhibitor therapy (median 11.6 years) or without (median 11.1 years) (P = 0.262), as was age at stage B2 (median 11.6 vs. 11.2 years; P = 0.753). In boys, both the age of attaining Tanner stage P2 (median 12.9 vs. 13.0 years; P = 0.796) and Tanner stage G2 (median 13.1 vs. 12.9 years; P = 0.344) were also similar with or without an mTOR inhibitor. Age at menarche in girls, and age at spermarche in boys, did not differ between the 2 groups.
Conclusions: In this retrospective analysis, sexual maturation ages and reproductive hormone levels were comparable in adolescent kidney transplant patients receiving low-exposure mTOR inhibitors and reduced CNI therapy or conventional CNI-based immunosuppression.