Context: An abundance of clinical reports focused on specific laboratory parameters have been reported on COVID-19, but a systematic analysis synthesizing these findings has not been performed.

Objective: To review and summarize the current available literature on the predictive role of various biomarkers in COVID-19 patients.

Data Sources: A literature search was performed using databases including PubMed, medRxiv, and bioRxiv. A total of 72 papers were reviewed including 54 peer reviewed papers and 18 non-peer reviewed preprints.

Conclusions: While non-specific, acute phase reactants including CRP, ferritin, SAA, and procalcitonin were reported as sensitive markers of acute COVID-19 disease. Significantly elevated WBC count, marked lymphopenia, decreased CD3, CD4 or CD8 T-lymphocyte counts, high neutrophil count, thrombocytopenia, and markedly elevated inflammatory biomarkers were associated with severe disease and the risk of developing sepsis with rapid progression. Trends observed by serial laboratory measurements during hospitalization including progressive decrease of lymphocyte count, thrombocytopenia, elevated CRP, procalcitonin, increased liver enzymes, decreased renal function, and coagulation derangements were more common in critically ill patient groups and associated with a high incidence of clinical complications. Elevated IL-6 level and markedly increased SAA were most often reported in severely and critically ill patients. Indicators of systemic inflammation such as neutrophil-lymphocyte ratio (NLR), systemic immune-inflammation (SII) index or COVID-19 Severity Score may be utilized to predict disease severity, outcome, and mortality. Interpretation of the data reported in the studies reviewed here is limited due to study design (mostly retrospective), limited sample size, and a lack of defined clinical criteria.

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Author notes

Drs. Tjendra and Al Mana contributed equally to this article.

The authors have no relevant financial interest in the products or companies described in this article.