[Fractional clearance of beta-2-microglobulin in the diagnostic and prognostic assessment of kidney diseases].
The micromolecular proteinuria (67-11 Kd), originating from tubulo-interstitial disorders, might be determined by SDS- or gradient-PAGE or by individual marker proteins. The latter procedure in addition to PAGE is necessary in case of heavy proteinurias. The tubular resorptive capacity for microproteins, analysed by fractional beta-2-M-clearances, decreases with deteriorating GFR. Values for FrCl beta 2M above the expected level were associated with tubulo-interstitial, but also with diabetic and rapidly progressing glomerular nephropathies. In the latter group these findings might be of prognostic importance. In contrast, the U-beta-2-M-determination in long term observation of kidney transplants had no diagnostic nor prognostic value.