Emerging evidence indicates a role for cardiac troponin testing, specifically high-sensitivity cardiac troponin (hs-cTn) in hospitalized patients with coronavirus disease 2019 (COVID-19).1Kavsak P.A. Hammarsten O. Worster A. Smith S.W. Apple F.S. Cardiac troponin testing in patients with COVID-19: a strategy for testing and reporting results [e-pub ahead of print]. Clin Chem.https://doi.org/10.1093/clinchem/hvaa225Google Scholar Undetectable levels of hs-cTn in patients with (and without) COVID-19 may be helpful in identifying a low-risk subgroup, with higher levels useful in identifying patients at high-risk for hospital death.1Kavsak P.A. Hammarsten O. Worster A. Smith S.W. Apple F.S. Cardiac troponin testing in patients with COVID-19: a strategy for testing and reporting results [e-pub ahead of print]. Clin Chem.https://doi.org/10.1093/clinchem/hvaa225Google Scholar,2Kavsak P.A. Cerasuolo J.O. Ko D.T. et al.High-sensitivity cardiac troponin I vs a clinical chemistry score for predicting all-cause mortality in an emergency department population.CJC Open. 2020; 2: 296-302Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar Further improvements in risk-stratification for emergency department or hospitalized patients may be achieved by adding clinical chemistry tests, such as glucose and creatinine (ie, estimated glomerular filtration rate), to generate a clinical chemistry score (CCS).2Kavsak P.A. Cerasuolo J.O. Ko D.T. et al.High-sensitivity cardiac troponin I vs a clinical chemistry score for predicting all-cause mortality in an emergency department population.CJC Open. 2020; 2: 296-302Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar,3Kavsak P.A. Cerasuolo J.O. Mondoux S.E. et al.Risk stratification for patients with chest pain discharged home from the emergency department.J Clin Med. 2020; 9: E2948Crossref PubMed Scopus (6) Google Scholar For patients with COVID-19, additional biochemical tests may have important prognostic roles—for example, urea level, which is already a component of the CURB-65 score (confusion, urea, respiratory rate, blood pressure, age ≥ 65 years) used to risk stratify patients presenting to the hospital with pneumonia.4Kavsak P.A. de Wit K. Worster A. Emerging key laboratory tests for patients with COVID-19.Clin Biochem. 2020; 81: 13-14Crossref PubMed Scopus (18) Google Scholar We performed a retrospective chart review of COVID-19 patients admitted to hospitals in the city of Hamilton in order to explore the performance characteristics of hs-cTn levels, the CCS, and the CCS with urea (CCUS) to predict in-hospital death. This review included the first 26 weeks of the COVID-19 pandemic (ethics approval: #11425-C). From March 16, 2020 to September 10, 2020, we identified 147 patients who were hospitalized at the Hamilton General Hospital, Juravinski Hospital, or St. Joseph's Healthcare, Hamilton with reverse transcriptase–polymerase chain reaction positive for severe acute respiratory syndrome coronavirus-2 (performed at the Hamilton regional laboratory medicine program; HRLMP). Of these 147 patients (3 still hospitalized), 48 (median age = 80 years) did not have hs-cTnI tests (Abbott [Chicago, IL] or Ortho Diagnostics [Raritan, NJ]), with an additional 40 without admission hs-cTnI measurement, leaving only 39 patients (median age = 72 years; 64% male; n = 13 deaths) with measures of admission hs-cTnI level, glucose level, estimated glomerular filtration rate, and urea level (P = 0.05 for age between groups). We calculated the CCS as has previously been described, with points ranging from 0 to 5.2Kavsak P.A. Cerasuolo J.O. Ko D.T. et al.High-sensitivity cardiac troponin I vs a clinical chemistry score for predicting all-cause mortality in an emergency department population.CJC Open. 2020; 2: 296-302Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar The CCUS includes the CCS with an additional point of 1 assigned if the urea level was > 7 mmol/L (0 if below), thus yielding a range of 0-6 points.2Kavsak P.A. Cerasuolo J.O. Ko D.T. et al.High-sensitivity cardiac troponin I vs a clinical chemistry score for predicting all-cause mortality in an emergency department population.CJC Open. 2020; 2: 296-302Abstract Full Text Full Text PDF PubMed Scopus (6) Google Scholar, 3Kavsak P.A. Cerasuolo J.O. Mondoux S.E. et al.Risk stratification for patients with chest pain discharged home from the emergency department.J Clin Med. 2020; 9: E2948Crossref PubMed Scopus (6) Google Scholar, 4Kavsak P.A. de Wit K. Worster A. Emerging key laboratory tests for patients with COVID-19.Clin Biochem. 2020; 81: 13-14Crossref PubMed Scopus (18) Google Scholar As 2 different hs-cTnI assays (Abbott = 29 patients; Ortho = 10 patients) were used, we divided the results by the respective upper reference limits to normalize for analyses. Receiver operating characteristic curve analyses with the areas under the curve, and sensitivity and specificity estimates for in-hospital death, were performed. The CCUS had the highest area under the curve for in-hospital death (0.81; 95% confidence interval [CI]: 0.65-0.92), higher than for hs-cTnI alone (0.69; 95% CI: 0.52-0.83; P = 0.01; Fig. 1). A CCUS ≤ 2 yielded a sensitivity = 92% (95% CI: 64-99) and a CCUS > 5 yielded a specificity = 92% (95% CI: 74-99). Major limitations include a small sample size and issues related to patient selection. This proof-of-principle study suggests that the prognostic performance of the hs-cTn level in patients with COVID-19 might be improved by the addition of routine biochemical tests. The Hamilton integrated research ethics board approved this study: #11425-C. This work received funding from a Canadian Institutes of Health Research grant (PK, funding reference #155964).