Your body holds vitamins and minerals
Think of your body like a bucket—holding minerals like phosphorus.
In XLH, THE BODY’s PHOSPHORUS “bucket” leaks
Your body needs phosphorus. In XLH, too much of it is lost. Here's what happens.
Phosphorus levels need to stay balanced
FGF23, a hormone, signals to the kidneys to remove any extra phosphorus through urine.
In XLH, phosphorus levels drop too low
XLH increases FGF23 activity, causing your body to lose phosphorus all the time.
Low levels of phosphorus can lead to weakened bones
Why does XLH cause too much FGF23?
A gene called PHEX helps regulate how much FGF23 your body makes. People with XLH have a change in their PHEX gene that causes an overproduction of FGF23. Because XLH is genetic, it can be passed down from parents to their children.
COMM-US-RDS-0998 August 2026