Serum neutrophil gelatinase-associated lipocalin (NGAL) correlates with clinical and endoscopic activity in ulcerative colitis but fails to predict activity in Crohn's disease.

Serum neutrophil gelatinase-associated lipocalin (NGAL) is a low molecular weight protein released from activated neutrophils and intestine epithelium whose mRNA expression is increased in inflamed intestinal tissue. The purpose of this study was to explore the relationship between serum NGAL level and activity of inflammatory bowel diseases. A total of 120 patients, 79 with Crohn's disease (CD) and 41 with ulcerative colitis (UC) were prospectively included into the study. Serum NGAL was measured by ELISA. The inflammatory activity of UC was assessed by Mayo score and of CD by CDAI and SES-CD scoring systems. Increasing endoscopic severity of UC from remission/mild to moderate/severe was associated with increasing NGAL levels from 46.9 to 66.4 ng/ml (P = 0.002). NGAL concentrations were significantly lower in patients with complete endoscopic and histologic remission than in the active UC (46.9 versus 66.4 ng/ml, P = 0.009). Also deterioration of the clinical activity of UC patients was associated with increasing level of NGAL from 44.9 in remission/mild to 68.0 ng/ml in moderate/severe grade (P = 0.002). NGAL levels correlated with CRP (r = 0.49), ESR (r = 0.48) and iron concentrations (r = -0.63), but not with faecal calprotectin. NGAL showed ability to distinguish endoscopically active from inactive UC with AUC-ROC of 0.758 (sensitivity 96% and specificity 54%). However NGAL levels showed no significant relationship with either clinical or endoscopic activity of CD. We conclude that serum NGAL level corresponds to clinical and endoscopic activity of UC and accurately predicts disease endoscopic remission.