Serum and urine cystatin C levels in children with post-pyelonephritic renal scarring: a pilot study.

Aim: We aimed to investigate in children with a history of acute pyelonephritis the influence of unilateral post-pyelonephritic renal scarring detected by DMSA scan on serum (S(CysC)) and urine cystatin C (U(CysC)) as well as upon other traditional markers of renal damage.
Methods: Children with DMSA proven pyelonephritis (n = 28) were grouped as either scar [+] (n = 19, unilateral renal scarring) or scar [-] (no scarring, n = 9). The scar [+] group was further divided into scar-1 (differential DMSA uptake, Delta(DMSA) </= 10%; n = 8) and scar-2 (Delta(DMSA) > 10%, n = 11) subgroups. S(CysC), serum creatinine, urine NAG, microalbumin, protein, fractional sodium excretion (FE(Na)), tubular phosphate reabsorption (TPR), and U(CysC/Cr) were evaluated in all patients.
Results: Neither S(CysC) nor U(CysC) were affected by age, height, and weight. scar [+] versus scar [-] groups and scar-1 versus scar-2 subgroups were not different with regard to all studied parameters. S(CysC) did not increase in children with post-pyelonephritic unilateral renal scarring. However, 11 children with slightly increased (>0.95 mg/l) S(CysC) levels in scar [+] group tended to have higher Delta(DMSA), albeit not significantly. Furthermore, U(CysC/Cr) correlated well with urine microalbumin, NAG, and FE(Na) in all children and the scar [+] group (P < 0.05).
Conclusion: S(CysC) and U(CysC) did not differ among pediatric patients with and without unilateral post-pyelonephritic renal scarring. However, Delta(DMSA) uptake between the two kidneys tended to be raised in children with S(CysC) levels higher than the reference ranges. Additionally, U(CysC/Cr) exhibits parallelism with tubular functions.