['To determine the relationship between inflammation and glucocorticoid metabolism in vivo, in a clinical study of patients with inflammatory arthritis treated with anti-TNFα therapy.', 'Urine samples were collected from patients with rheumatoid arthritis (RA) and psoriatic arthritis (PsA) as part of a multicentre study assessing responses to infliximab and etanercept. Systemic measures of glucocorticoid metabolism were assessed by gas chromatography/mass spectrometry at weeks 0 (baseline), 4 and 12 after anti-TNFα therapy. Clinical data including DAS28 and C-reactive protein were also collected.', 'Systemic measures of 11β-HSD1 activity in patients with inflammatory arthritis decreased significantly following anti-TNFα therapy in patients with RA and PsA. Additionally, the activity of the glucocorticoid inactivating enzyme 5α-reductase appeared to increase significantly.'] Does tNFα regulate cortisol metabolism in vivo in patients with inflammatory arthritis?