Anti-Inflammatory Agents, Non-Steroidal/pharmacology; Antibodies, Monoclonal, Humanized/pharmacology; Azathioprine/metabolism; Crohn Disease/metabolism; Immunosuppressive Agents/metabolism; Adalimumab; Adolescent; Adult; Anti-Inflammatory Agents, Non-Steroidal/therapeutic use; Antibodies, Monoclonal, Humanized/therapeutic use; Azathioprine/pharmacokinetics; Azathioprine/therapeutic use; C-Reactive Protein/metabolism; Crohn Disease/drug therapy; Drug Interactions; Drug Therapy, Combination; Erythrocytes/enzymology; Female; Guanine Nucleotides/blood; Humans; Hypoxanthine Phosphoribosyltransferase/blood; Immunosuppressive Agents/pharmacokinetics; Immunosuppressive Agents/therapeutic use; Male; Methyltransferases/blood; Middle Aged; Prospective Studies; Pyrophosphatases/blood; Severity of Illness Index; Thioinosine/analogs & derivatives; Thioinosine/blood; Thionucleotides/blood; Young Adult; Inosine Triphosphatase

6-MMPR; 6-MP; 6-TGN; 6-TGTP; 6-methylmercaptopurine ribonucleotides; 6-thioguanine nucleotides; 6-thioguanine triphosphate; 95% CI; 95% confidence interval; AZA; Adalimumab; Azathioprine; C-reactive protein; CD; CDAI; CRP; Crohn's disease; Crohn's disease activity index; Drug interaction; HGPRT; HPLC; IBD; IMP; ITPase; MCV; Mercaptopurine; RBC; TDM; TPMT; Therapeutic drug monitoring; UC; azathioprine; high performance liquid chromatography; hypoxanthine-guanine phosphoribosyl transferase; inflammatory bowel disease; inosine monophosphate; inosine triphosphate pyrophosphatase; mean corpuscular volume; mercaptopurine; red blood cells; therapeutic drug monitoring; thiopurine S-methyltransferase; ulcerative colitis