Despite relevant research in renal biomarkers, there is currently no optimal marker available that reliably quantifies kidney function and indicates kidney injury in its early stages. The combination of two or more biomarkers might be a more promising approach than investigating a single parameter. The relationship of renal biomarkers (creatinine, albumin, Cystatin C, NGAL, beta-trace protein, beta-2 microglobulin, and uromodulin) between each other and the variation over age in infants and children (without chronic kidney disease) is investigated.~The biomarkers in urine samples are explored to find less invasive means of quantifying renal health.~Patients between the age of 0 and 12 years undergoing blood with or without urine sampling as part of their diagnostic workup are eligible for the study. Unused residual blood and urine samples will be used for testing the renal parameters.
To characterize the relationship of renal biomarkers (Creatinine, albumin, Cystatin C, NGAL, beta-trace protein, beta-2 microglobulin, and uromodulin) between each other and the variation over age, measured in serum and urine of healthy children. Unused residual blood and urine samples will be used for testing the renal Parameters.