Effect of letrozole on the predicted adult height in boys with constitutional delay of growth and puberty: A clinical trial

Objectives: The aim of this was to investigate the effect of letrozole (an aromatase inhibitor) on the Predicted Adult Height (PAH) in boys with constitutional delay of growth and puberty. Methods: In this clinical trial, the boys with constitutional delay of growth and puberty referred to Endocrine Research Center, Institute of Endocrinology and Metabolism, Iran University of Medical Sciences. Tehran was studied. Patients were treated with letrozole (letrofome, Iran Hormone Manufacturing Co., Tehran, Iran) at a dose of 2.5 mg for one year and then discontinued for 6 months and patients were followed up. Results: During one year taking letrozole, bone age was progressed from 12.49 +/- 0.9 y to 13.18 +/- 0.7 y and 13.64 +/- 0.7 at 6 months after discontinuation. PAH at baseline was 172.5 +/- 5.4 cm and after 12 and 18 months was 175.2 +/- 4.3 and 174.9 +/- 5.4 cm, respectively. PAH mean difference at baseline and 12th month was 2.8 cm (P=0.02), and at 12th and 18th months was -0.3 cm (P=0.70). In bone densitometry, Z-score of spine during treatment with letrozole and after discontinuation increased to 0.084 +/- 0.3 and 0.083 +/- 0.1, respectively, and the difference was not significant. Mineral density of the femoral neck in the treatment period, 0.04 decreased, but after discontinuation the treatment, 0.4 increased that change was not significant. Conclusions: The study provides an indication for the treatment with letrozole (aromatase inhibitors) increase PAH with slowing the progression of bone age and letrozole has no adverse effects on bone metabolism and serum lipids.