--and even the quantitative immunglobulin screen is to look to see if you have too much in the way of monoclonal or polyclonal antibodies--the Kappa/Lambda screen is to type them if they're there (and I wouldn't be surprised if an immunofixation electrophoresis is also included).

All of those tests are looking for dysfunction of the antibody system, which is not only associated in many cases with neuropathy but with blood disorders.

See:

http://neuromuscular.wustl.edu/antibody/mprotein.htm