Indeterminate Results of QuantiFERON-TB Gold In-Tube Assay in Nonimmunosuppressed Children

Background and Aims QuantiFERON-TB Gold In-Tube (QFT-IT) assay is a highly sensitive and specific test for the diagnosis of latent tuberculosis infection. Data on the use of QFT-IT assay in children are scarce and contradictory. The aim of the study was to assess the rate of indeterminate test results and to identify factors contributing to indeterminate results on routine use of QFT-IT assay in nonimmunosuppressed children. Methods This retrospective study included 2173 children with ages ranging from 1 month to 18 years. Determination of interferon-gamma (IFN-γ) in peripheral blood was performed by commercial QFT-IT assay. Results Indeterminate test results were recorded in ten (0.46%) subjects with ages ranging from 15 months to 15 years. The value of negative control was >8.0 kIU/L in one subject, whereas in the remaining nine subjects indeterminate results were consequential to positive control (