Background: High-sensitivity (hs) cardiac troponin (cTn) assays quantifies cTn in most healthy men and women. Whether quantifiable cTn concentrations below the 99 th percentile upper-reference limit have short term prognostic implications in emergency department (ED) patients remains uncertain. Methods: Multicenter (n=22) United States (US) cohort of ED patients undergoing at least one hs-cTnT measurement (CV Data Mart Biomarker cohort). For this assay, the lowest reportable concentration is <6 ng/L. Sex-specific 99 th percentiles of 10 ng/L for women and 15 ng/L for men were used. The primary outcome was index hospitalization mortality. Results: A total of 85610 patients were examined, including 43043 women and 42567 men. A total of 775 index hospitalization deaths (0.91%) occurred, including 361 (0.84%) in women and 414 (0.97%) in men. Among women, baseline hs-cTnT concentrations were non-quantifiable (<LoQ) in 37.5%, quantifiable (LoQ-99 th ) in 21.6%, and increased >99 th percentile in 40.9%. Among men, baseline hs-cTnT concentrations were non-quantifiable (<LoQ) in 20.0%, quantifiable (LoQ-99 th ) in 37.4%, and increased >99 th percentile in 42.6%. Patients with higher concentrations were more likely to be older and had more comorbidities. Continuous baseline hs-cTnT (log) were associated with a higher odds of index hospitalization mortality (OR 1.26, 95% CI 1.24-1.28). Following multivariable analyses, quantifiable hs-cTnT (LoQ-99 th ) also were associated with index hospitalization mortality in all patients (OR 2.07, 95% 1.22-3.53), and in both women (OR 3.13, 95% CI 1.51-6.50) and men (OR 2.17, 95% 1.28-3.69) (Figure). Conclusions: Hs-cTnT concentrations within the reference range are more common in men than in women. Quantifiable hs-cTnT concentrations within the sex-specific reference range are associated with a higher risk of index hospitalization mortality, with a larger prognostic effect in women than in men.