Is a blood test to diagnose paraneoplastic syndrome experimental?

Maybe. Some defined antibodies are associated with paraneoplastic syndromes (note: plural). In those cases the testing may be positive. However, a person could have a paraneoplastic syndrome with negative testing for the known paraneoplastic antibodies. It is possible that studies are being done to characterize tests for paraneoplastic syndromes. That might be experimental.
No. Tests for the various autoantibodies such as anti-Hu are well-established.

Related Questions

Lo back muscles stiff an dull headache sweating an trouble with balance. If this is paraneoplastic syndrome will it show on blood tests?

More information. Do you have cancer?? Paraneoplastic syndrome takes many forms and sometimes includes large levels of normal hormones! The symptoms are NON-SPECIFIC.....We need more info so ask your question again.... Dr Z.