High-value Laboratory Testing for Hospitalized COVID-19 Patients: A Review

Abstract

We present here an evidence-based review of the utility, timing, and indications for laboratory test use in the domains of inflammation, cardiology, hematology, nephrology and co-infection for clinicians managing the care of hospitalized COVID-19 patients. Levels of IL-6, CRP, absolute lymphocyte count, neutrophils and neutrophil-to-lymphocyte ratio obtained upon admission may help predict the severity of COVID-19. Elevated lactate dehydrogenase, ferritin, aspartate aminotransferase, and ᴅ-dimer are associated with severe illness and mortality. Elevated cardiac troponin at hospital admission can alert clinicians to patients at risk for cardiac complications. Elevated proBNP may help distinguish a cardiac complication from noncardiac etiologies. Evaluation for co-infection is typically unnecessary in nonsevere cases but is essential in severe COVID-19, intensive care unit patients, and immunocompromised patients.

Lay abstract

Doctors managing the complex care of individuals with COVID-19 need timely evidence to guide which lab tests to send to predict outcomes and prevent and treat COVID-19 complications involving the heart, blood clots, the kidney, and other infections that occur during the hospital course. Several lab tests such as IL-6, CRP and white blood cell subset counts may help predict the severity of COVID-19 during the patient’s hospital course if obtained when the patient first presents to the hospital. Other tests such as lactate dehydrogenase, ferritin and aspartate aminotransferase are also associated with severe illness and mortality but have less evidence for their utility beyond IL-6, CRP and other tests. A test related to blood coagulation, ᴅ-dimer, is also associated with COVID-19 severity, and it may be used if the patient is suspected of having a blood clot. Two heart biomarkers – cardiac troponin and proBNP – may help doctors diagnose and manage heart-related complications of COVID-19. Patients in the hospital with COVID-19 may be susceptible to other infections, but testing for these is most useful in patients with severe disease, such as those in the intensive care unit. Specific recommendations for testing for viral, bacterial and fungal infections are presented here. The judicious use of laboratory testing can help identify patients at high risk for severe or critical COVID-19 and aid in prevention, diagnosis and treatment of common COVID-19 complications.

Keywords:

• CRP
• COVID-19
• ᴅ-dimer
• high value care
• IL-6
• inpatient
• laboratory test
• labs
• SARS-CoV-2
• troponin

Acknowledgments

The authors thank S Karaba, J Townsend, N Chida, K Carroll, MV Fabre, E Scully, R Avery, LL Smith, B Bodnar, P Welling and R Naik for literature review. The authors also thank D Brotman, RS Stephens, C Lowenstein, P Auwaerter, M Melia, E Avdic, DL Thomas, C Hoffmann, N West and C Herzke for review of the text.

Financial & competing interests disclosure

KA Marr is a consultant and/or advisor for Amplyx, Cidara, Merck and Sfunga and receives equity and/or licensing revenue from MycoMed Technologies. MB Streiff reports research funding from The Patient-Centered Outcomes Research Institute, the Agency for Healthcare Research and Quality, Boehringer-Ingelheim, Janssen, Portola and Roche. MB Streiff has also consulted for Bristol Myers Squibb, Dispersol, Janssen, Pfizer and Portola and has given expert witness testimony in various medical malpractice cases. AAR Antar receives research funding from NIAID-NIH (K08 award) that was not specifically given for the writing of this review article. The authors have no other relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript apart from those disclosed.

No writing assistance was utilized in the production of this manuscript.