--stands for "serum protein electrophoresis one" which is simply a testing protocol that looks through your profile of serum proteins for rogue antibodies (monoclonal or M-proteins, which can be associated with blood cancers and, though cross-reactivities, cause neuropathy).

If you have neuropathy, though, the more specific test for this is the immunofixaton electrophoresis (IFE) with globulin enumeration. A serum protein electrophoresis will tell you how much alpha, beta, and gamma globulins there are and if any are in too great a supply, but small elevations in monoclonals may be obscured in the overall gamma globulin figures. An immunofication of serum and urine will break apart the specific types of gamma globulin (IgA, IgM and IgG), enumerate them, and see if any of the protein chains are monoclonal.

Take a look at:

http://en.wikipedia.org/wiki/Immunofixation

http://www.wardelab.com/21-2.html