By comparing urine samples from 21 active TB, 24 LTBI, and 18 healthy controls via LC–MS/MS, Young et al. identified IGKC, RBP4, PTGDS, AMBP, ORM1, IGCL2, and SECTM1 as potential protein biomarkers for distinguishing TB from LTBI or healthy control samples. Here, IGKC is linked to tuberculosis.