Hep B

Initial Hep B lab results:

HBsAg (Hepatitis B surface antigen)
Not detected = Normal
Detected =  Abnormal

Why it works? Detects protein (antigen) that is present on the surface of the virus
When do you use it? To screen for, detect, and help diagnose acute and chronic HBV infections; earliest routine indicator of acute hepatitis B and frequently identifies infected people before symptoms appear; undetectable in the blood during the recovery period; it is the primary way of identifying those with chronic infections, including "HBV carrier" state.

anti-HBs (Hepatitis B surface antibody) 
Negative = Normal
Detected = Normal (after vax) or Abnormal (after infxn 

Why it works? Detects antibody produced in response to HBV surface antigen
When do you use it? Used to detect previous exposure to HBV; it can also develop from successful vaccination so it is used to determine the need for vaccination (if anti-HBs is absent) or to determine if a person has recovered from an infection and is immune (cannot get the infection again).

anti-HBc (Total anti-Hep B core, IgM, IgG)
Negative = Normal
Detected = Abnormal
Why it works? Detects both IgM and IgG antibodies to hepatitis B core antigen
When do you use it? Can be used to help detect acute and chronic HBV infections; the IgM antibody is the first antibody produced after infection with HBV; IgG antibody is produced in response to the core antigen later in the course of the infection and usually persists for life.





Read more: 
https://labtestsonline.org/understanding/analytes/hepatitis-b/tab/test/
https://www.cdc.gov/hepatitis/HBV/PDFs/SerologicChartv8.pdf