| Abbreviation | Definition |
|---|---|
| ALS | Alveolar-Like Structure |
| ALS | Amyotrophic Lateral Sclerosis |
| ALS | AntiLymphocytic Serum |
| ALS | Auto-immune Lymphoproliferative Syndrome |
| ALT | Alternate |
| ALTDIEB | Alternate Days |
| ALTHOR | Alternate Hours |
| ALTNOCT | Alternate Nights |
| ALTS | Acute lumbar trauma syndrome |
| ALVAL | Aseptic Lymphocytic Vasculitis-Associated Lesion |
| ALVF | Acute left ventricular failure |
| ALZ | Alzheimer's disease |
| AM | Adult male |
| AM | Aerospace Medicine |
| AM | Before Noon |
| AM | In the Morning, before Noon |
| AM | Morning |
| AMA | Acute Metabolic Acidosis |
| AMA | Advanced Maternal Age |
| AMA | Against Medical Advice |