Choudhary RK, et al. - In view of the association of blood monocyte-to-lymphocyte ratio (MLR) with active tuberculosis (TB) in adults, researchers examined its value as TB diagnostic biomarker in HIV-infected children in whom respiratory sampling is difficult. They determined absolute monocyte and lymphocyte counts at enrollment and 4, 12, and 24 weeks thereafter in a cohort of 160 HIV-infected hospitalized Kenyan children with median age 23 months initiating antiretroviral therapy. Among these, 13 (8.1%) had confirmed TB and 67 (41.9%) had unconfirmed TB. Children with confirmed TB were identified with the MLR above 0.378 with 77% sensitivity, 78% specificity, 24% positive predictive value, and 97% negative predictive value. These findings support the efficacy of blood MLR in distinguishing HIV-infected children with confirmed TB from those with unlikely TB and declined with TB treatment. For settings where respiratory-based microbiologic confirmation is inaccessible, MLR seems to be a useful diagnostic tool for TB.