Spot urine concentrations of type I collagen cross-linked N-telopeptides and deoxypyridinoline in psoriatic arthritis

The main objectives of this study were to investigate whether the spot urine concentrations of type I collagen cross-linked N-telopeptides (NTx) and deoxypyridinoline (Dpd) can be used to distinguish between active and suppressed disease in psoriatic arthritis (PsA) and to study the relationship between these markers of bone resorption and disease activity indices. Using enzyme-linked immunosorbent assays, concentrations of NTx and Dpd were estimated in spot urine samples from 25 patients with active disease, 10 patients with suppressed disease and 35 age- and sex-matched healthy control subjects. In patients with active disease, urine concentrations of NTx and Dpd were significantly elevated (p0.05) when compared with those with suppressed disease. In active disease, there was no significant positive correlation between urinary NTx and erythrocyte sedimentation rate (ESR) (r = 0.025, p>0.05) nor between Dpd and ESR (r = -0.208, p>0.05). In conclusion, NTx and Dpd concentrations in spot urine have no association with disease activity in patients with PsA.