Differentiation of hematuria by quantitative determination of urinary marker proteins

Hematuria caused by prerenal, glomerular, postglomerular, and postrenal causes is usually differentiated by a number of noninvasive and invasive diagnostic procedures. In the present study we have applied a new analytical strategy based on observations that the various forms of hematuria can be classified by their typical protein pattern. When analyzed by quantitative turbidimetric assays, urines from postrenal hematurias contained high-molecular-weight proteins (alpha 2-macroglobulin and IgG) in proportions found in plasma. Relating excretion rates (mg/mg) of these proteins to those of albumin, ratios for alpha 2-macroglobulin/albumin and IgG/albumin were 2.0-31 x 10(-2) and 20.0-180 x 10(-2), respectively. In contrast, glomerular hematurias exhibited ratios of 0.01-2.0 x 10(-2) (alpha 2-macroglobulin/albumin) and 2.0-20 x 10(-2) (IgG/albumin). Additional determination of alpha 1-microglobulin allowed us to differentiate postglomerular hematurias caused by interstitial nephropathies from glomerular and postrenal diseases. Critical evaluation of 93 cases diagnosed by independent clinical examination including histology, sonography, and cystoscopy revealed that the criteria derived from protein measurements resulted in correct classification when urine albumin exceeds 100 mg/l. This noninvasive procedure is expected to be of considerable help in the primary care of patients with unexplained hematuria.