| IAD | inactivating dose; instructional advance directive; internal absorbed dose |
|---|---|
| IAM | Institute of Applied Microbiology [Japan]; Institute of Aviation Medicine; internal auditory meatus |
| IAS | immunosuppressive acidic substance; infant apnea syndrome; insulin autoimmune syndrome; interatrial ... |
| ICA | Institute of Clinical Analysis; internal carotid artery; intracranial aneurysm; islet cell antibody |
| ICAO | internal carotid artery occlusion |