What differential diagnostic criteria should be considered in the diagnosis of Corona?
The PCR test is the most reliable method used worldwide in the diagnosis of corona. However, in some cases even PCR tests do not provide correct results. This is because qualified sampling is not always possible due to the requirement to take nasal samples by use of a special swab for PCR testing by specialist and experienced healthcare professionals. In this respect, it would be wise to support PCR test results through cross-checking with antibody tests.
Apart from these biochemical tests, some supportive diagnostic criteria are used to determine whether patients applying to healthcare institutions with regular symptoms of simple influenza or cold have the coronavirus. Firstly, complaints of the patient (fever, Cough, inability to distinguish tastes and odours, fatigue etc.) are checked. Then, certain biochemistry, hormone and blood values are examined. These are generally the changes in CRP, PCT, Ferritin, Il-6, il-10, D-Dimer and lymphocyte values that also occur in Corona virus infection cases, which we call inflammatory markers. Corona virus infection diagnosis can be supported by considering together high CRP value accompanying a normal PCT value, Interleukin-6 and Interleukin-10 levels that are 4 times higher than normal and high Ferritin and low lymphocyte values.
Since the coronavirus causes its most serious direct damage in the lungs, oxygen saturation falls below critical values in many patients presenting disease symptoms, due to respiratory failure and shortness of breath. In this respect, blood oxygen values, which may fall below the normal SpO2 level of 93%, should be monitored by use of a pulse-oximeter device making measurements at the fingertip and various respiratory support units should be used when necessary.
Apart from these, the most important diagnostic finding to support PCR test results in early infection and antibody tests in late infection periods is lung images provided through Computerised Tomography, since the image of the lungs becomes more opaque and frosted in case of coronavirus infection, when compared to the transparent image of a healthy lung. In this respect, tomography findings facilitate the diagnosis of corona and the determination of the level of progression of the disease.