Abstract
Background: A biomarker to discriminate active from latent mycobacterium (m.) tuberculosis infection could help in exclusion of occult tuberculosis and avoid under treatment of those patients. Neopterin is released by macrophages in response to stimulation by interferon gamma.
Objective: To assess whether urinary levels of neopterin can discriminate between latent and active mycobacterium tuberculosis infection.
Methods: Urinary neopterin/creatinine ratio's were determined in patients with active and latent m. tuberculosis infection and controls without m. tuberculosis infection. Latent m. tuberculosis infection was defined as reactive interferon gamma release assay for m. tuberculosis in the absence of active disease.
Results: Seven patients with active tuberculosis, 27 patients with latent m. tuberculosis infection and seven controls were recruited. There was no difference in age or gender between groups. Urinary neopterin/creatinine ratio was higher in patients with active tuberculosis (412.8 micromol/mol, 95% CI 89.7 to 735.8) than patients with latent m tuberculosis infection (147.5 micromol/mol, 95% CI 114.0 to 180.8) and controls (122.2 micromol/mol, 95% CI 71.2 to 173.1) (p<.01). ROC curve analysis revealed an area under the curve of 0.81 (95% CI 0.62 to 0.99). A cut-off of 349 micromol/mol showed 100% diagnostic specificity in detection of active tuberculosis in people with m. tuberculosis infection.
Conclusions: Urinary neopterin/creatinine ratios are significantly higher in patients with active tuberculosis compared to patients with latent m. tuberculosis infection. These findings suggest that neopterin appears to be a suitable marker to reflect tuberculosis disease activity.
- © 2011 ERS