Biomarkers of Kidney Disease
1Department of Clinical Chemistry, University Hospital, Lund, Sweden
There is no shortage of markers for renal disease and at least 32 tests of protein concentrations in plasma or urine are used to discover and follow renal disease. We need markers for glomerular filtration rate (GFR), glomerular damage, tubular/interstitial damage and for assessing risk for acute renal failure.
Recent progress (1,2) has established that the best way to estimate GFR is by combined use of cystatin C- and creatinine-based GFR-estimating equations for adults, whereas for children use of only cystatin C-based equations are sufficient (www.egfr.se).
Glomerular damage/leakage can be graded by analysis of IgG, IgM, core protein-glycosaminoglycans and podocin in urine. By measuring the IgG2 and IgG4 subclasses in urine, abnormalities in the charge selectivity of the glomerular membrane can be defined.
Tubular/interstitial damage can be demonstrated by analysis of free protein HC (alias free alpha-1-microglobulin), beta-2-microglobulin and free kappa- and lambda-chains in urine.
For assessment of risk for acute renal failure the plasma and urine concentrations of Neutrophil Gelatinase Associated Lipocalin (NGAL) has mostly been used, but also the urine level of free protein HC and the plasma level of cystatin C have been used.
1. Grubb A et al: Generation of a new cystatin C-based estimating equation for glomerular filtration rate using seven assays standardized to the international calibrator. (2014) Clin Chem 60; In press. http://www.clinchem.org/content/early/2014/04/28/clinchem.2013.220707.abstract
2. Nyman U et al: The revised Lund-Malmö GFR estimating equation outperforms MDRD and CKD-EPI across GFR, age and BMI intervals in a large Swedish population. (2014) Clin Chem Lab Med 52: 815-824.
Keywords: Biomarker, Kidney, Method