| UR | unconditioned response |
|---|---|
| UR | Utilisation review |
| Ura | Uracil |
| URD | Unrelated donor |
| Urd | Uridine |
| Urd Pase | uridine phosphorylase |
| URE | upstream regulatory element |
| URI | Upper respiratory infection |
| URI | upper respiratory tract infection |
| URL | uniform resource locator |