| Abbreviations | Meaning |
 | CHUSPAN | [treatment Of] Churg-Strauss Syndrome And Polyarteritis Nodosa [study] |
 | CIBPS | Chronic Intractable Benign Pain Syndrome |
 | CIDS | Cellular Immunity Deficiency Syndrome |
 | CIHS | Central Infantile Hypotonic Syndrome |
 | CINCA | Chronic Infantile Neurological Cutaneous And Auricular [syndrome] |
 | CJS | Creutzfeldt-Jakob Syndrome |
 | CLAS | Circulating Lupus Anticoagulant Syndrome |
 | CLC | Clerc-Levy-Critesco (syndrome) |
 | CLC | Charcot-Leyden Crystal; Clerc-Levy-Critesco [syndrome] |
 | CLH | Cleft Limb-heart (syndrome) |
 | CLH | Chronic Lobular Hepatitis; Cleft Limb-heart [syndrome]; Corpus Luteum Hormone; Cutaneous Lymphoid Hyperplasia |
 | CLS | Coffin-Lowry Syndrome |
 | CLS | Cornelia De Lange Syndrome |
 | CLS | Cafe-au-lait Spot; Classical Least Square; Clinical Laboratory Scientist; Coffin-Lowry Syndrome; Cornelia De Lange Syndrome |
 | CMS | Chronic Myelodysplastic Syndrome |
 | CMS | Clofibrate-induced Muscular Syndrome |
 | CMT | Charcot-Marie-Tooth [syndrome] |
 | CMTS | Charcot-Marie-Tooth Syndrome |
 | CMTX | Charcot-Marie-Tooth [syndrome], X-linked |
 | CN | Crigler-Najjar [syndrome] |
 | CNES | Chronic Nervous Exhaustion Syndrome |
 | CNF | Congenital Nephrotic Syndrome Of The Finnish [type] |
 | CNFS | Craniofrontonasal Syndrome |
 | CNS | Congenital Nephrotic Syndrome |
 | COA | Canadian Ophthalmological Association; Canadian Orthopaedic Association; Certificate Of Authority; Cervico-oculo-acusticus [syndrome]; Condition On Admission |
 | COACH | Canadian Organization For The Advancement Of Computers In Health; Cerebellar Vermis Hypoplasia/aplasia-oligophrenia-congenital Ataxia-ocular Colobomata-hepatic Fibrosis [syndrome] |
 | COBS | Cesarean-obtained Barrier-sustained; Chronic Organic Brain Syndrome |
 | COD-MD | Cerebro-ocular Dysplasia-muscular Dystrophy [syndrome] |
 | CODAS | Cerebro-oculo-dento-auriculo-skeletal [syndrome] |
 | COFS | Cerebro-oculo-facial-skeletal [syndrome]; Certificate Of Free Sale |
 | COMS | Cerebrooculomuscular Syndrome |
 | COS | Carbon Oxysulfide; Cheiro-oral Syndrome; Chief Of Staff; Clinically Observed Seizures; Clinical Orthopaedic Society |
 | COVESDEM | Costovertebral Segmentation Defect With Mesomelia [syndrome] |
 | CPLS | Cleft Palate-lateral Synechia Syndrome |
 | CPPD | Calcium Pyrophosphate Dihydrate Deposition [syndrome]; Cisplatin; Cost Per Patient Day |
 | CPS | Cervical Pain Syndrome |
 | CPS | Chest Pain Syndrome |
 | CPS | Chronic Prostatitis Syndrome |
 | CPSC | Congenital Paucity Of Secondary Synaptic Clefts [syndrome]; Consumer Products Safety Commission |
 | CRASH | Corpus Callosum Hypoplasia-retardation-adducted Thumbs-spastic Paraplegia-hydrocephalus [syndrome] |
 | CREST | Calcinosis, Raynaud Phenomenon, Esophageal Involvement, Sclerodactyly, And Telangiectasia [syndrome]; Carotid Revascularization And Endarterectomy Vs Stent Trial |
 | CROME | Congenital Cataracts-epileptic Fits-mental Retardation (syndrome) |
 | CROME | Congenital Cataracts-epileptic Fits-mental Retardation [syndrome] |
 | CRPS | Complex Regional Pain Syndrome (type I And II) |
 | CRPS | Complex Regional Pain Syndrome [types I And II] |
 | CRS | Caudal Regression Syndrome |
 | CRS | Chinese Restaurant Syndrome |
 | CRS | Congenital Rubella Syndrome |
 | CRST | Calcinosis, Raynaud Phenomenon, Sclerodactyly, Telangiectasia [syndrome]; Corrected Sinus Recovery Time |
 | CS | Climacteric Syndrome |