The measurement of urinary marker
proteins is not a generally accepted laboratory practice because the results are difficult to interpret. MDI-LABLINK is software for classifying patterns of specific urinary marker
proteins. The interpretations are completely user definable thanks to a specific 'pattern definition database'. Our interpretation set is based on Hofmann and Guder's work in measuring and interpreting single urinary
proteins. We include additional marker
proteins in order to adapt Boesken's SDS-PAGE classification. During the last 3 years, 1905 patterns were fully differentiated and identically interpreted. Firstly, the samples were classified into three patterns: normal (25.8%), predominantly glomerular (27.2%, selective, unselective, mixed, and with additional tubular
proteins) and predominantly tubular (36.9%, complete/incomplete form, with additional glomerular
proteins); 8.9% showed postrenal
proteinuria. Secondly, glomerular selectivity measured by using urinary
transferrin/
IgG ratio alone correlates well with the established SI index (the ratio between
IgG and
transferrin clearances). Thirdly, the
creatinine concentration substantiates the validity of the sample. The quality of the preanalytical phase can be improved through the ongoing education of the medical staff. Finally, measurement of urinary
albumin and
alpha-1-microglobulin is mandatory where
kidney disease is suspected, has to be ruled out, or requires close monitoring, even when the total
protein concentration is normal.