Validation of Serum Creatinine Dosage and Renal Clearance

Inclusion Criteria: * Normal weight as defined by a Body Mass Index of 18 to 30 kg/m2. * Subject is competent and willing to sign informed consent form after being given all the detailed information about the study. Informed consent form signed voluntarily. * The subjects must be in stable clinical condition, with stable serum creatinin at least for 6 months. * Persons with different stage of chronic renal disease and without kidney disease (living donors) who need an evaluation of the GFR or Admitted volunteers who easily obtain urine samples. Exclusion Criteria: * Transplant patients * Medication that will influence the serumcreatinine. * Morbid obesity * Pregnant, lactating females or females with childbearing potential without adequate contraception (use of oral contraceptives, IUD or condoms with spermicide). * History of allergy or hypersensitivity to inulin * Donation of blood in the 60 days preceding the first visit. * Liver disease, heart failure, nephrotic syndrome. * Patients in critically ill conditions. * Malnutrition * Postrenal kidney failure