| Abbreviation | Definition |
|---|---|
| ISH | Isolated Systolic Hypertension |
| ISI | Insulin Sensitivity Index |
| ISI | Inter-Stimulus Interval |
| ISL | InterScapular Line |
| ISS | Injury Severity Score |
| ISS(s) | injury severity score(s) |
| IST | Insulin Shock Therapy |
| IST | Intravascular Sono-Therapy |
| ISTA | International Society for Technology in Arthroplasty |
| IT | Individual Therapy |
| IT | Inhalation Therapy |
| IT | Intensive Therapy |
| ITBS | Iliotibial Band Syndrome |
| ITCB | Ishihara's Tests for Color Blindness |
| ITE | In The Ear |
| ITEC | Instant Tennis Elbow Cure |
| ITM | Intuitive Treatment Management |
| ITP | Idiopathic Thrombocytopenic Purpura |
| ITS | I'm Tired Syndrome |
| ITT | Internal tibial torsion |