Drug serum concentrations will be measured at several time-points for inflammatory disease patients treated with anti-TNF agents. The purpose is to determine which patients that will clinically benefit from either discontinue treatment, adjusting the dose, switch to another anti-TNF agent or a different class of medication.

Crohn´s disease and ulcerative colitis are diseases where the proinflammatory cytokine Tumor Necrosis Factor-alpha (TNF) plays an important role. Anti-TNF agents are used in the treatment. However, some patients do not respond and response rates declines over time. The cause may be immunogenicity against the agent itself, the agent´s failure to neutralize TNF or another biological pathway leading to inflammation. Anti-TNF agents have been administrated as fixed doses at certain frequencies and this may not be optimal for all patients, but recent studies have indicated a correlation between efficacy and serum drug concentration levels (trough levels). Our preliminary data suggest that trough levels early in the treatment course may be predictive of later trough levels. By multiple measurements, this will be assessed. The study will also investigate biological markers in serum and blood cells which may be predictable for trough levels. Finally, we will compare different methods to measure serum drug concentrations.

Inclusion Criteria:

• Patients diagnosed with Inflammatory bowel disease
• Treated with anti-TNF drug
• Follow-up at specialized gastroenterologist in Norway
• Age 18 or over

Exclusion Criteria:

• Patients refusing to participate by not giving their informed consent

Patients with Inflammatory bowel disease treated with anti-TNF drug