Tumor Induced Osteomalacia (TIO)

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888.355.0470
xlhrarecare@pantherxrare.com

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Kyowa Kirin, Inc.
www.kkna.kyowakirin.com

Tumor Induced Osteomalacia (TIO) is a rare paraneoplastic syndrome that causes low levels of phosphorus in the body and weakens bones. TIO is the result of small tumor(s) in the body that produce high levels of a protein called fibroblast growth factor 23 (FGF23). High levels of FGF23 cause the body to eliminate too much phosphate in the urine, which can cause bones to become weak.

Like other types of cancer, TIO is an acquired condition meaning that it is not present at birth and is diagnosed later in life. Due to the tumors small size and slow growing nature, TIO tumors may take anywhere from 2.5-28 years to be diagnosed from the first sign of symptoms.

Symptoms

Diagnosis

Diagnosis of TIO can be a long and difficult process due to the tumors small size and slow growth. Some tumors can be as small as 1 cm (about the size of a pea).

A TIO causing tumor can be found using magnetic resonance imaging (MRI) or by a process called an octreotide scan, which uses a special medication that binds to the tumor making it easier to find during scans.

If the tumor cannot be found on imaging, doctors will usually rule out other causes of hypophosphatemia (low phosphorus) such as X-linked hypophosphatemia (XLH), autosomal dominant hypophosphatemic rickets (ADHR), and autosomal recessive hypophosphatemic rickets (ARHR).

Treatment

TIO can be cured by complete removal of the tumor. If the tumor cannot be found or safely removed, medications are available to help raise phosphate levels such as oral phosphate supplementation and calcitriol (active vitamin D3). Another type of medication called a FGF23 blocking antibody can be used to decrease phosphate wasting in the urine and increase phosphate and vitamin D levels in the body.

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