The Coronavirus Disease (COVID-19) pandemic first broke out in December 2019 in 
Wuhan, China, and has now spread worldwide. Laboratory findings have been only 
partially described in some observational studies. To date, more comprehensive 
systematic reviews of laboratory findings on COVID-19 are missing. We performed 
a systematic review with a meta-analysis to assess laboratory findings in 
patients with COVID-19. Observational studies from three databases were 
selected. We calculated pooled proportions and 95% confidence interval (95% CI) 
using the random-effects model meta-analysis. A total of 1106 articles were 
identified from PubMed, Web of Science, CNKI (China), and other sources. After 
screening, 28 and 7 studies were selected for a systematic review and a 
meta-analysis, respectively. Of the 4,663 patients included, the most prevalent 
laboratory finding was increased C-reactive protein (CRP; 73.6%, 95% CI 
65.0-81.3%), followed by decreased albumin (62.9%, 95% CI 28.3-91.2%), increased 
erythrocyte sedimentation rate (61.2%, 95% CI 41.3-81.0%), decreased eosinophils 
(58.4%, 95% CI 46.5-69.8%), increased interleukin-6 (53.1%, 95% CI 36.0-70.0%), 
lymphopenia (47.9%, 95% CI 41.6-54.9%), and increased lactate dehydrogenase 
(LDH; 46.2%, 95% CI 37.9-54.7%). A meta-analysis of seven studies with 1905 
patients showed that increased CRP (OR 3.0, 95% CI: 2.1-4.4), lymphopenia (OR 
4.5, 95% CI: 3.3-6.0), and increased LDH (OR 6.7, 95% CI: 2.4-18.9) were 
significantly associated with severity. These results demonstrated that more 
attention is warranted when interpreting laboratory findings in patients with 
COVID-19. Patients with elevated CRP levels, lymphopenia, or elevated LDH 
require proper management and, if necessary, transfer to the intensive care 
unit.