When Ann, a mother, wife, and college professor, noticed she was more tired than ever and getting weak after being active, she knew something wasn’t right. It soon became difficult for her to walk and stand, which led her to seek and push for a diagnosis for what she was experiencing. After seeing many specialists, Ann was diagnosed with tumor-induced osteomalacia (TIO). While her tumor(s) have not yet been found, she continues to have hope and advocate for herself.

Resource Guide for Patients and Care Partners

Download our resource guide for information on TIO, including how to manage symptoms, mental health, appointments, and lifestyle modifications.

What is it?

Tumor-induced osteomalacia (TIO) is a rare disease caused by tumors.

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.

Common names for TIO1

  • Oncogenic osteomalacia
  • Oncogenic hypophosphatemic osteomalacia

1Oncogenic osteomalacia. National Institutes of Health: Genetic and Rare Diseases Information Center Website. https://rarediseases.info.nih.gov/diseases/9652/oncogenic-osteomalacia. Updated October 19, 2017. Accessed March 29, 2019.

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