Acute Hepatitis B can be earliest diagnosed by?

For the diagnosis of HBV infection detection of HBsAg in the blood is all that ordinarily necessary. The simultaneous presence of IgM anti-HBc indicates recent infection.occassionally when the level of HBsAg is too low to be detectable, the diagnosis has to be made by testing for IgM anti-HBc. REF:ANANTHANARAYAN AND PANIKER'S TEXTBOOK OF MICROBIOLOGY 9TH EDITION PAGE NO-547