If the purpose of the blood test is to determine which type of pathogen is responsible for HFMD, then the items to look for are antibodies to coxsackievirus group A type 16 or enterovirus 71, and a positive antibody indicates an infection with this pathogen. However, there are other types of pathogens that cause HFMD that cannot be fully determined by blood tests, and these viruses are likely to cause insidious infections, i.e., no clinical symptoms or just herpes pharyngitis. Therefore, it is not possible to determine whether or not HFMD is caused by looking at antibodies to this pathogen; clinical symptoms must be present before HFMD can be called HFMD. If the purpose of looking at the relevant items is to determine the severity of HFMD, you can look at the white blood cell count, which is likely to be severe if it is greater than 15 in units of 10^9. If the C-reactive protein is also high, this can be corroborated from the side, while liver function, cardiac enzymes, and kidney function are used to determine whether the HFMD has caused damage to the liver, kidneys, and heart muscle.