Glossary

A

Active vitamin D

(pronounced: AK-tiv VY-tuh-min dee)

A type of vitamin D that is already in a form your body can use right away. It helps control calcium and phosphorus levels in the blood to support healthy bones. Active vitamin D can be made by the body or given as a medicine. Active vitamin D can also be called calcitriol, 1,25(OH)₂D, or 1,25 dihydroxyvitamin D.

F

Fibroblast growth factor 23 (FGF23)

(pronounced: FY-broh-blast grohth fak-tor twenty-three)

A protein that helps control the amount of phosphorus in the blood. In TIO, the levels of FGF23 are abnormally increased, causing the body to release excess phosphorus in the urine.

Fractures

(pronounced: FRAK-churz)

Breaks or cracks in bones that happen when they are weak or under too much pressure.

H

Hormone

(pronounced: HOR-moan)

A chemical in your body that sends signals to help different parts of your body work properly.

Hypophosphatemia

(pronounced: hy-po-FOS-fuh-TEE-mee-uh)

A condition where there is not enough phosphorus in the blood, which can weaken bones.

M

Mineralization

(pronounced: min-er-uhl-eye-ZAY-shun)

The normal process where minerals like phosphorus and calcium harden bones and teeth, making them strong. When mineralization is impaired, bones can become soft or weak.

O

Oral phosphate

(pronounced: OR-uhl FOS-fate)

A medicine taken by mouth that adds phosphorus to your body to help keep bones strong.

Osteoid volume to bone volume ratio

(pronunciation: OSS-tee-oyd VOL-yoom too bohn VOL-yoom RAY-shee-oh)

A measurement that shows how much new, soft bone (osteoid) there is compared to the total amount of bone. This helps doctors understand how well bones are forming and hardening.

Osteomalacia

(pronounced: ah-stee-oh-muh-LAY-shuh)

A condition in which bones become soft and weak.

P

Phosphorus

(pronounced: FOS-fuh-ruhs)

A mineral your body needs to keep bones strong and healthy.

Phosphate wasting

(pronounced: FOS-fayt WAY-sting)

A condition where the kidneys lose too much phosphorus through the urine.

S

Subcutaneous injection

(pronounced: sub-kew-TAY-nee-uhs in-JEK-shun)

A method of delivering medicine just beneath the skin through a shot.

T

Tumor-induced osteomalacia

(pronounced: TOO-mer in-DOOST ah-stee-oh-muh-LAY-shuh)

A rare condition where a usually noncancerous tumor produces too much of a hormone called FGF23 that causes the body to lose too much phosphorus. This leads to soft, weak bones that can cause pain, fractures, and difficulty walking.

V

Vitamin D

(pronounced: VY-tuh-min DEE)

A vitamin that helps the body absorb calcium and phosphorus from food, supporting healthy bones.

Vitamin D supplement

(pronounced: VY-tuh-min DEE SUP-luh-ment)

A form of vitamin D taken to help raise vitamin D levels when the body does not get enough from sunlight or food.