Indeterminate result of interferon-gamma release assay in a child: review of literature with illustrative case

Abstract

Interferon-gamma release assays (IGRAs) have off ered signifi cant progress in the detection of M. tuberculosis infection. In addition to obtaining negative or positive results of IGRAs, there is a possibility of getting indeterminate results. An indeterminate test result indicates situations where it is not possible to determine the state of M. tuberculosis infection. Interpretation and accurate follow-up of children with indeterminate test results pose diagnostic challenges for clinicians. The aim of the present review is to show an illustrative case of a 15-month-old boy with indeterminate result of the QuantiFERON-TB Gold In-Tube test (QFT-GIT, Cellestis Ltd., Carnegie, Australia) during pneumonia, to point out the problems associated with getting indeterminate results. Follow-up test result after recovery was negative. QFT-GIT should preferably be performed upon resolution of acute infl ammation with standardization of preanalytical and analytical factors in order to avoid indeterminate results. Furthermore, evidence-based guidelines on the optimal follow-up of children with indeterminate results will be important as IGRAs use becomes increasingly widespread.