Evaluate myeloma, macroglobulinemia of Waldenström, lymphoma, amyloidosis; differentiate between normal renal function, glomerular proteinuria, and tubular proteinuria. Increased glomerular permeability leads to higher concentrations of large proteins in the glomerular filtrate. Diminished tubular reabsorptive capacity results in a marked increase in urinary excretion of low molecular weight problems.