TNF and inflammatory bowel disease: The most recent American Gastroenterological Association (AGA) guideline on Therapeutic Drug Monitoring in Inflammatory Bowel Disease suggests target trough levels for patients on maintenance therapy with TNF-alpha inhibitors (infliximab ≥ 5 μg/mL, adalimumab ≥ 7.5 μg/mL, and certolizumab pegol ≥ 20 μg/mL) [46].