Nephelometric measurement of human serum prealbumin and correlation with acute-phase proteins CRP and SAA: results in familial amyloid polyneuropathy.

Prealbumin, a negative acute-phase reactant, has a role as a clinical index of patient status after inflammation, trauma, or surgery that is gaining recognition. We developed a rate nephelometric assay that allows quantitation of prealbumin levels in a large number of samples to be performed quickly, efficiently, and reproducibly. The generation of data by this method is more rapid and precise than the alternative measurement techniques of radioimmunoassay, radial immunodiffusion, and electroimmunoassay. Nephelometric analysis of serum prealbumin in 33 patients with familial amyloidosis showed significantly depressed concentrations compared with levels in normal individuals and in patients with primary and secondary amyloidosis. Prealbumin levels were compared with corresponding amounts of the acute-phase proteins C-reactive protein and serum amyloid A in the three amyloid groups. Lowered prealbumin concentrations corresponded to elevated levels of C-reactive protein and serum amyloid A in the sera from patients with primary and secondary amyloidosis. In the group with familial amyloidosis, however, the lower than normal levels of prealbumin did not correspond to elevations in C-reactive protein and serum amyloid A. Our data suggest that depressed plasma prealbumin concentrations noted in individuals with familial amyloidosis are not simply reflections of a negative acute-phase response.