Rapid assessment of renal reserve in young adults by cystatin C

AbstractBackground. The kidney can increase glomerular filtration rate (GFR) in response to a protein load (renal reserve). In a pilot study of healthy young adults we examined renal reserve using changes in serum cystatin C (cysC). Methods. Glomerular filtration rate was obtained using iohexol single slope plasma disappearance. To stimulate GFR, subjects ingested a beefburger containing 60 grams of protein. CysC was measured by immunonephelometry before and 125–141 minutes after protein loading. Results. All subjects were found to have a normal iohexol plasma disappearance GFR with a mean of 104.6 ± 9.9 mL/min per 1.73 m2. CysC decreased in each subject after the meat meal. Baseline cysC-based estimated GFR was 98.1 ± 9.1 mL/min per 1.73 m2 with a mean increase of 12.0 ± 5.2 (p = 0.0003). Conclusions. Our study showed a consistent decrease in serum cysC and increase in cysC-based estimated GFR following a protein load in young adults. Further studies are needed using renal clearance methods to confirm th...