Cystatin C in children on chronic hemodialysis

Abstract

Cystatin C (CyC) concentration has been suggested as a marker of middle-molecule accumulation, hemodialysis (HD) adequacy and for estimating residual renal function (RRF), but it has not been studied in pediatric HD. High CyC is associated with increased cardiovascular disease (CVD). We investigated CyC kinetics and the effect of RRF on CyC in a pediatric HD population. A total of 21 HD sessions and 20 interdialytic periods were analyzed in seven patients, age 5-19 years, of whom four were anuric (A) and three were non-anuric (NA). CyC was measured before (preHD) and after (postHD) three standard HD sessions in 1 week and prior to the first session of the following week. We found no difference (p=0.67) in CyC concentration between preHD CyC (9.85 ± 2.15 mg/l; A vs. NA, p=0.37) and postHD CyC (10.04 ± 2.83 mg/l; A vs NA, p=0.28). The weekly average preHD CyC median concentration was 10.14 mg/l (A vs. NA, p=0.87) and correlated with age (r=0.808, p=0.03) and height measurement (r=0.799, p=0.03), but not with RRF, single-pool Kt/V, ultrafiltration, HD duration or blood liters processed. Cystatin C is very elevated in children on HD. It does not rise between HD sessions, is not removed by standard HD and remains at steady state; therefore, elimination is extrarenal. Low RRF does not affect CyC elimination. CyC increases with age and height. If a high CyC concentration can be proven to have a causative role in the development of CVD, routine intensified HD regimens in children may be indicated for its removal.