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 urin e concentrations of type I collagen cross-linked N-telopeptides (NTx) and d eoxypyridinoline (Dpd) can be used to distinguish between active and suppre ssed disease in psoriatic arthritis (PsA) and to study the relationship bet ween these markers of bane resorption and disease activity indices. Using e nzyme-linked immunosorbent assays, concentrations of NTx and Dpd were estim ated in spot urine samples from 25 patients with active disease, 10 patient s with suppressed disease and 35 age- and sex-matched healthy control subje cts. In patients with active disease, urine concentrations of NTx and Dpd w ere significantly elevated (p<0.001) compared with healthy controls and the re were no significant differences (p>0.05) when compared with those with s uppressed disease. In active disease, there was no significant positive cor relation 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.