To investigate the influence of early therapeutic drug monitoring and dose optimization on disease outcome in Crohn's patients treated with Adalimumab.

This is an investigator initiated randomized open label study. This study is designed to compare whether increasing the dose of adalimumab based on the level the drug in the blood to a target level early in the treatment course would lead to better outcomes for patients as compared to the standard doses.

Inclusion Criteria:

• Age 18 or older.
• Crohn's disease diagnosed based on standard objective methodology (clinical, biochemical, endoscopic, histological and radiological correlation).
• Active disease based on Harvey Bradshaw Index (HBI >5) and elevated C-reactive protein (CRP) (>normal reference range for local laboratory) OR fecal calprotectin (FCP) (>250 µg/g)
• Due to commence treatment with ADAL.

Exclusion Criteria:

• Severe co-existing cardiopulmonary, hepatic, renal, neurologic, or rheumatologic disease.
• History of active HIV, hepatitis B or C infection,
• Patients with ileostomy/colostomy, ileal-pouch anal anastomosis or severe perianal fistulising disease.
• Pregnancy
• Prior exposure to ADAL

Some of the participants, care providers and investigators will eventually, in the course of the study, have knowledge of the arm they were assigned.