Laboratory indicators in asymptomatic and presymptomatic
COVID-19 patients
On admission, the most common computed tomography (CT) findings were
ground-glass opacity and lung-texture increase in asymptomatic (83% and
50%, respectively), presymptomatic (83% and 61%, respectively), and
symptomatic (92% and 62%, respectively) patients, with no significant
intergroup differences (18). Other chest CT characteristics such as
fuzzy boundary (range 8–17%), consolidation (0–12%), and pleural
thickening (range 4–7%) were observed in asymptomatic, presymptomatic,
and symptomatic patients, but without statistical significance.
Interestingly, pleural effusion (7%), fine reticular opacity (2%), and
lymph node enlargement (1%) were only observed in symptomatic patients
(Fig. 3A). The presence of enlarged lymph nodes in symptomatic patients
may indicate a stronger immune response.
To obtain more information on the affected organs, we compared
laboratory indicators between the groups of asymptomatic,
presymptomatic, and symptomatic COVID-19 patients. The rates of abnormal
(one-fold away from the reference range) laboratory indicators
associated with liver and kidney function were all above 60% in each
group (Fig. 3B), and the rates of abnormal laboratory indicators
associated with heart function were less than 40%. Specifically, when
the threshold for abnormality was set to two-fold points from the
reference range, asymptomatic patients showed lower rates of abnormal
laboratory indicators of hepatic function (2.8% vs 20%,P -value < 0.05) and cardiac function (5.7% vs10%, P -value > 0.05) and comparable rates in terms
of kidney function (11.43% vs 10%, P -value
> 0.05, Fig. 3C) than presymptomatic patients. Abnormal
levels of lactate dehydrogenase, albumin, uric acid, D-dimer (DD),
C-reactive protein, and calcium were less frequently observed in
asymptomatic and presymptomatic patients than in symptomatic patients
(Fig. 3D, Table S2 and Table S3). These analyses indicate that the liver
and kidney were the most common affected organs in all COVID-19
patients, whereas indicators for heart and liver function showed the
most significant differences between asymptomatic and presymptomatic
patients.