High faecal calprotectin levels in intestinal tuberculosis are associated with granulomas in intestinal biopsies

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Background: The diagnosis of intestinal tuberculosis (ITB) is sometimes difficult to establish and requires endoscopic investigation with biopsies for histopathological examination. This study aimed to evaluate calprotectin as a marker of inflammation in ITB. Methods: Patients with ITB were prospectively recruited in Southern India from October 2009 until July 2012. Demographic, clinical, endoscopic and histological features were examined along with faecal calprotectin (FC), serum calprotectin (SC) and C-reactive protein (CRP). Results: Thirty patients (median age 34.5 years, 19 men) were included. Clinical features were abdominal pain (97%), weight loss (83%), cachexia (75%), fatigue (63%), watery diarrhoea (62%), nausea (55%) and fever (53%). Endoscopy showed transverse ulcers (61%), nodularity of mucosa (55%), aphthous ulcers (39%), strictures (10%) and fissures (10%). The terminal ileum and right colon harboured 81% of the lesions. Histology revealed granulomas in biopsies from 10 of the patients. FC and CRP levels showed a strong positive correlation (rs = 0.70, p < 0.01). FC, SC and CRP levels were higher in the granulomatous than the non-granulomatous patients, respectively (median FC 988 μg/g, interquartile range (IQR) 940 vs 87 μg/g, IQR 704, p < 0.01; median SC 8.2 μg/ml, IQR 7.3 vs 3.8 μg/ml, IQR 8.9, p = 0.23; median CRP 38.8 mg/L, IQR 42.9 vs 2.3 mg/L, IQR 13.5, p < 0.01). Higher median calprotectin and CRP levels were detected in patients with extensive than localized disease, but the differences did not reach statistical significance. Conclusion: ITB patients with granulomas on histology have high levels of faecal calprotectin and CRP.