| NAR | nasal airway resistance; National Association for Retarded [Children, Citizens]; no action required |
|---|---|
| NARAL | National Abortion Rights Action League |
| NAT | N-acetyltransferase; natal; neonatal alloimmune thrombocytopenia; no action taken; nonaccidental tra... |
| RA | radioactive; ragocyte; ragweed antigen; rapidly adapting [receptors]; reactive arthritis; reciprocal... |
| RAT | repeat action tablet; rheumatoid arthritis test |