Third-generation Aromatase Inhibitor Improved Adult Height in a Japanese Boy with Testotoxicosis

In this study, we report a Japanese boy with testotoxicosis due to a heterozygous mutation [p. A572V] in the LH/CGR gene, who was the first boy treated with a third-generation aromatase inhibitor (AI) and reached his adult height in Japan. He showed accelerated growth and rapid penile growth from 3 yr of age and was diagnosed as having testotoxicosis. Combined treatment with anastrozole and spironolactone was started when he was 7 yr old and 145.8 cm (+4.45 SD) tall, at which point his bone age (BA) was 13.5 yr. His predicted adult height (PAH) was estimated to be 158.3 cm. The combined treatment was continued until he was 13 yr old and 166.5 cm tall, with his BA being 15.5 yr. He reached his adult height of 166.9 cm at 15 yr of age. Combined treatment with anastrozole and spironolactone successfully decelerated BA advancement, prolonged pubertal period and improved adult height.