I had an avise test done - ana igg of 24.09 and it said 'positive'. what is the likelihood i have lupus? i have pericarditis too, for over a year now. other specific antibodies showed negative. are there other tests to confirm it is lupus?

ANA is not specific for lupus and ANA + is not uncommon. You stated that other specific antibodies are negative so I assume the specific tests for systemic lupus, SLE, such as dsDNA antibody and/or Smith antibody were done and negative. If these Abs are negative, SLE is almost ruled out. If they weren't done, you can request them done for ruling out SLE. Pericarditis is often caused by virus.

Lupus,rheumatoid arthritis and mixed connective tissue disease can cause pericarditis but generally other symptoms of those diseases are also present. If you're being treated for the pericarditis with immunosuppressants, the usual autoimmune markers may be suppressed as well. I trust that you're being followed,advised and treated by a cardiologist as well as a rheumatologist.