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Letrozole Monotherapy in Pre- and Early-Pubertal Boys Does Not Increase Adult Height

Tero Varimo1, Sanna Toiviainen-Salo2, Taneli Raivio1,3

  • 1Pediatric Research Center, Children's Hospital, Helsinki University Hospital, Helsinki, Finland.

Frontiers in Endocrinology
|April 27, 2019
PubMed

Insights

Aromatase inhibitors (AIs) did not improve adult height in boys with idiopathic short stature (ISS). Long-term follow-up confirmed similar adult heights and vertebral deformity rates between AI-treated and placebo groups, indicating no significant benefit or harm.

Area of Science:

  • Pediatric Endocrinology
  • Growth Disorders
  • Pharmacological Interventions

Background:

  • Aromatase inhibitors (AIs) are used off-label for idiopathic short stature (ISS) in boys.
  • Limited data exist on the long-term effects of AIs on adult height in this population.

Purpose of the Study:

  • To evaluate adult height outcomes in boys with ISS treated with letrozole (Lz) or placebo (Pl).
  • To assess long-term skeletal safety and vertebral deformity changes following AI treatment.

Main Methods:

  • Randomized, double-blind, placebo-controlled trial involving boys treated with Lz or Pl for 2 years.
  • Adult height and spine MRI data were collected for long-term follow-up.
  • Bone age was assessed at treatment cessation.

Main Results:

  • Adult heights were comparable between the Lz and Pl groups (164.8 cm vs. 163.7 cm).
  • Adult heights in both groups did not significantly differ from predicted adult heights at baseline.
  • Vertebral deformity frequencies were similar between groups (29% Lz vs. 22% Pl), with no clear enrichment of comorbidities.

Conclusions:

  • Letrozole treatment did not significantly improve adult height in pre- or early-pubertal boys with ISS.
  • Previously observed vertebral deformities showed amelioration during follow-up.
  • Letrozole therapy appears to be skeletally safe in children and adolescents with ISS.

Keywords:
MRIadult heightidiopathic short statureletrozolelong-term follow-up

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