| ANA panel |
| Anaerobe |
| Anaerobic bacteria |
| Analgesics – screen |
| Angiogram |
| Angiogram – coronary |
| Angiography |
| Angiography – aorta |
| Angiography – head |
| Angiography – heart |
| Angiography – left heart |
| Angiography – magnetic resonance |
| Angiography – renal |
| Angiography – right heart |
| Angiography/arteriography of the extremity |
| Anoscopy |
| Anthrax serology test |
| Anti-DNase B |
| Anti-gastric parietal cell antibodies |
| Anti-GBM antibodies |
| Anti-glomerular basement membrane |
| Anti-insulin antibody test |
| Anti-P antibody |
| Anti-smooth muscle antibody |
| Antibiotic sensitivity |
| Antibody test for anthrax |
| Antibody titer |
| Antibody to human glomerular basement membrane |
| Antideoxyribonuclease B titer |
| Antidepressants – screen |
| Antidiuretic hormone |
| Antimicrosomal antibody |
| Antimitochondrial antibody |
| Antinuclear antibody panel |
| Antiparietal cells antibodies |
| Antistreptolysin O titer |
| Antithrombin III |
| Antithyroglobulin antibody |
| Antithyroid microsomal antibody |
| Aortic angiography |
| Aortography |
| APCA |
| APGAR |
| ApoB100 |
| ApoCII |
| Apolipoprotein B100 |
| Apolipoprotein CII |
| Apoprotein B100 |
| Apoprotein CII |
| APTT |
| Arginine test |
| Arginine vasopressin |
| Arterial blood gas analysis |
| Arterial stick |
| Arteriogram |
| Arteriogram – abdomen |
| Arthroscopy |
| Artificial kidneys |
| ASLO |
| ASO titer |
| Aspartate aminotransferase |
| Aspergillosis precipitin |
| Aspergillus immunodiffusion test |
| AST |
| AT III |
| Attention span |
| Audiography (audiogram) |
| Audiology |
| Audiometry |
| Autoimmune liver disease panel |
| Automated perimetry exam |
| AVP |
