Hi, everyone. I’m Dr. Shanlee Davis. I’m a pediatric endocrinologist that works at the Children’s Hospital, Colorado, and the University of Colorado Anschutz Medical Campus. Here we have the Extraordinary Kids Clinic, a specialty clinic for children with XXY and other X and Y variations. I will review some of the most common questions as a pediatric endocrinologist. I take care of many boys with Klinefelter Syndrome.
So the first question is: What hormones do you need to measure? When do you need to measure them?
Hypothalamic pituitary gonadal access is a big long word that we often refer to as HPG access isn’t even active until true puberty starts. The brain sends signals to the testes to tell them to make testosterone. This is when the start of puberty is initiated. This can happen anywhere from age 9 to 14 in typically developing boys. And we see the exact onset of puberty in Klinefelter syndrome. However, as puberty progresses in Klinefelter syndrome, the testes can’t keep up with the demand for making testosterone in the rest of the body. And so the brain starts sending out signals louder and louder.
Those signals are called Gonadotropin for LH and FSH, and we can measure these hormones in the blood. So once puberty starts, the doctors should begin to evaluate the exam, how the body changes over time, and what these labs look like in the blood. So LH FSH and total testosterone. The relationship between those labs makes a difference when deciding when and how to consider starting testosterone replacement in boys with Klinefelter Syndrome.