An extensive investigation of the anthropometric measurements in males with 47,XXY (Klinefelter Syndrome) from birth to five years of age and the impact of early hormonal treatment (EHT)

Aim: 47,XXY (KS) is the most frequently occurring sex chromosome aneuploidy (SCA) with an incidence rate of 1:500 to 1:650 live male births. 47,XXY is characterized by androgen insufficiency and hypogonadism, diminished phallus size, hypotonia, and increased stature. This investigation examines the relationship between Early Hormonal Treatment (EHT) and growth in boys with 47,XXY from birth to 5 years. Methods: A cohort of 134 males with 47,XXY was seen as part of a natural history study and anthropometric measurements were completed at each evaluation for height (HGT), weight (WGT), and head circumference (HC). Data was analyzed for these factors in the group receiving testosterone as EHT (T group) and a no treatment (No-T) control group. Results: Significant differences in HC were observed between the T group and No-T group for birth to 12 months. There was no other significant difference in HC for boys between the ages of 13 to 60 months. Only significant differences were observed in the birth to 12 months group for HGT between the T group and No-T group. There were only significant differences in WGT in the birth to 12-month age range between the T group and the No-T group, as well as in the 12-24-month age range. Conclusion: EHT is not associated with reducing or advancing growth in children with 47,XXY over 2 years old. After 24 months of age there is no discernible difference between boys with 47,XXY with EHT and without EHT.