What is it?

Tumor-induced osteomalacia (TIO) is a rare disease caused by tumors that appear and grow in the extremities (hands and feet).

What causes it?

TIO is typically caused by slow-growing tumors, which produce excess amounts of FGF23, a protein that regulates phosphate and vitamin D, both of which are important for bone health.

What are some of the common symptoms?

  • Muscle weakness
  • Fatigue
  • Bone pain
  • Fractures

How many people have it?

Approximately 500 – 1,000 people in the U.S. are living with TIO.

If you are aware of any Tumor-induced Osteomalacia (TIO) groups, please contact patientadvocacy@ultragenyx.com.