Can you have lupus with a negative ANA test? What about other autoimmune disorders?

ANA testing. ANA is a screening test for autoimmune disease, (generally present in 80-90% of cases). A higher titer over 1:160 is more significant. There are more definite testing for lupus such as anti-smith antibody and anti ds dna antbody. There are many more other specific testing for other specific autoimmune disorders. Syphilis and lyme disease can give false positive ANA test as well. See your md.
Yes. ANA is a generalized marker that can be seen in a host of autoimmune disorders, and is certainly not specific for one. Lupus erythematosus is a systemic disorder, although there are localized form, discoid forms, etc. Therefore, other disease can come into the differential diagnosis, and usually a biopsy or other laboratory tests can help to sort it out.