Urine for the diagnosis of tuberculosis: current approaches, clinical applicability, and new developments

Urine is increasingly being investigated as a convenient clinical sample for the identification of mycobacterial products for the diagnosis of tuberculosis. The available literature on mycobacterial lipoarabinomannan (LAM) and urine mycobacterial DNA is reviewed.

The available data, despite being extracted from heterogeneous clinical populations and different clinical subgroups, indicate that urine LAM has little diagnostic utility in unselected tuberculosis suspects; however, test characteristics improve in HIV-infected patients, particularly those with advanced immunosuppression (CD4 cell count <200 cells/microl). Methodologies for urine PCR for detection of mycobacterial DNA vary across studies and focus is on standardizing assays with respect to specimen collection, assay design, and processing methodology.

Both the urine LAM and PCR for mycobacterial DNA are being evaluated in different geographical settings. Urine LAM currently offers little utility for the diagnosis of tuberculosis in unselected populations. However, urine LAM appears promising as a diagnostic tool in HIV-infected patients with CD4 cell counts less than 200 cells/microl in different clinical settings. Further developmental studies are required to enhance the performance of the assays, and their usefulness over sputum microscopy in HIV-infected patients with advanced immunosuppression requires definition in large cohort studies.