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CYSTATIN C CALCULATED GFR- A MARKER OF EARLY RENAL DYSFUNCTION IN
PATIENTS WITH NEUROPATHIC BLADDER
Pankaj DANGLE, Audry KANG , Omar AYYASH and Glenn CANNON JR.
The Children's Hospital of Pittsburgh, Pediatric urology, Pittsburgh, USA
PURPOSE
Wheel chair bound meningomyelocele (MMC) patients inherently have low muscle mass, and assessing renal
deterioration based on creatinine based glomerular filtration rate is imprecise. MMC patients are also at risk for end
stage renal disease (ESRD). We have previously reported that based on cystatin based GFR, 18% of children with MMC
were upstaged to a higher stage of end stage renal disease. We hypothesize that cystatin c calculated GFR can reveal
ESRD not detected by creatinine-based calculations in a larger prospective cohort of children with MMC.
MATERIAL AND METHODS
Prospectively enrolled patients with MMC underwent annual serum creatinine and cystatin c testing. The anthropometric
measurements were obtained from clinic visit. Modified (bedside) Schwartz formula for creatinine based GFR and
Zappitelli cystatin C formula was utilized for calculation. The exclusion criteria were patients with reduced GFR (CKD
stage 2) or chronic CKD (CKD stage 3 and greater), these patients were excluded from analysis on the premise that
they had already been identified for closer renal monitoring.
RESULTS
A total of 117 patients were included in the analysis. The median creatinine based estimated glomerular filtration rate
was [131] ml per minute/1.73 m
2
(range [93] to [466]). The median cystatin C based estimated rate was [102] ml per
minute/1.73 m
2
(range [58] to [171]) yielding an absolute median rate reduction of [34%]. Using cystatin c-calculated
GFR, chronic kidney disease stage was upgraded from stage 1 to 2 in [34] patients (29%).
CONCLUSIONS
In MMC patients with poor muscle mass, Cystatin C based GFR is more sensitive than creatinine-based GFR in detecting
early ESRD . In this high-risk population, serial Cystatin C estimation is a valuable tool in identifying children who may
benefit from early nephrology referral and intervention.