3.2 Laboratory examination
In the early stage of the COVID-19, white blood cell count is normal or decreased, with decreased lymphocyte count. Some patients may present elevated levels of liver enzymes, lactate dehydrogenase, muscle enzymes and myoglobin. The level of troponin may be increased in critically ill patients. Severe cases showed high level of D-dimer and progressively decreased blood lymphocytes count(Jin et al., 2020). The critical patients often have elevated level of inflammatory factors such as IL2, IL7, IL10, GSCF, IP10, MCP1, MIP1a and TNF-α (Chaolin et al., 2020).
Based upon the evidence from clinical research, the SARS-CoV-2 nucleic acids can be detected in nasopharyngeal swabs, sputum, lower respiratory tract secretions using reverse transcription-polymerase chain reaction (RT-PCR) method(Rothan & Byrareddy, 2020). Some scholar reported that both IgM and IgG titres were markedly increased in nearly all patients, which was normally considered as a transition from earlier to later period of infection(Zhang et al., 2020). Therefore, they developed IgM and IgG detection methods using a cross-reactive nucleocapsid protein(NP) from another SARSr-CoV Rp3, which is 92% identical to 2019-nCoV NP.