| AHI | active hostility index; Animal Health Institute; apnea-plus-hypopnea index |
|---|---|
| AIBS | American Institute of Biological Sciences |
| AIH | amelogenesis imperfecta, hypomaturation type; American Institute of Homeopathy; artificial inseminat... |
| AIN | acute interstitial nephritis; American Institute of Nutrition; anterior interosseous nerve |
| AIPS | American Institute of Pathologic Science |
| NIBSC | National Institute for Biological Standards and Control |
|---|---|
| NICE | National Institute for Clinical Excellence |
| NIOSH | National Institute for Occupational Safety and Health |
| NIA | National Institute of Aging |
| NIAAA | National Institute of Alcohol Abuse and Alcoholism |