| UN | Uranyl nitrate |
|---|---|
| UN | Urea nitrogen |
| UN | unilateral nephrectomy |
| UNA | Urea nitrogen appearance |
| UNDW | Ultrasonically nebulized distilled water |
| UNG | Uracil DNA glycosylase |
| UNG | Uracil N-glycosylase |
| UNHS | Universal newborn hearing screening |
| UNICEF | United Nations Children's Found |
| uNK | Uterine natural killer |