Cystatin C and neutrophil gelatinase- associated lipocalin as markers of renal function in pediatric heart transplant recipients Improved long-term survival after PHT has bestowed increasing attention on managing co-morbidities such as CKD (1). The prevalence of CKD is known to increase with increasing duration since transplant (2, 3). Moreover, CKD has significant association with mortality in PHT recipients (4). Hence, there is a need to define measures for early recognition of CKD in these patients so that a timely referral and manage- ment strategy can be adopted. While the direct measurement of GFR by methods such as inulin clearance or nuclear medicine scintigraphy would be ideal to follow kidney function in the PHT recipients, they are relatively invasive tests. Previously published reports have used Schwartz formula or absolute serum creatinine to deter- mine renal function (2, 5, 6). While the Schwartz formula is much more practical than the direct measurement of GFR, it has several limitations. It overestimates creatinine clearance by 12– 33 mL/min/1.73 m 2 compared with direct mea- surement of GFR and is inaccurate in obese or malnourished children or in critically ill children with rapidly changing GFR (6–8). Cystatin C has been shown to be an alternative to creatinine in estimating renal function in adult and pediatric kidney and liver transplant recipi- ents (9–13). Unlike the Schwartz formula, it is Abraham BP, Frazier EA, Morrow WR, Blaszak RT, Devarajan P, Mitsnefes M, Bryant JC, Sachdeva R. Cystatin C and neutrophil gelatinase-associated lipocalin as markers of renal function in pediatric heart transplant recipients. Pediatr Transplantation 2011: 15: 564–569. Ó 2011 John Wiley & Sons A/S. Abstract: We hypothesized that use of Schwartz formula underesti- mates the prevalence of CKD in PHT recipients. This study determined the prevalence and risk factors for CKD in PHT using novel methods- serum cystatin C, CKiD formula, Revised Schwartz formula, s- and u-NGAL. Serum BUN, creatinine, cystatin C and s- and u-NGAL were measured after prospective enrollment. Schwartz formula GFR was compared with novel methods. CKD was defined as CKiD GFR < 90 mL/min/1.73 m 2 . The s- and u-NGAL were compared between those with and without CKD. Potential risk factors for CKD were analyzed. Seventy-nine patients (46 male children or boys), mean age 9.9 ± 5.8 yr formed the study cohort. The prevalence of mild and moderate CKD was 2- to 3-fold higher using novel methods compared to Schwartz formula. u-NGAL and u-NGAL/Cr were significantly higher in patients with CKD. u- and s-NGAL had negative correlation with estimates of GFR. Women were at a higher risk for CKD (odds ratio 8.7) as was longer duration since transplant (p = 0.009). In con- clusion, use of novel methods of GFR estimation unmasked 2- to 3-fold increased prevalence of CKD in PHT. Women and those with longer duration since transplant are at higher risk for CKD. Boban P. Abraham 1 , Elizabeth A. Frazier 1 , W. Robert Morrow 1 , Richard T. Blaszak 2 , Prasad Devarajan 3 , Mark Mitsnefes 3 , Janet C. Bryant 1 and Ritu Sachdeva 1 1 Pediatric Cardiology, 2 Pediatric Nephrology, Arkansas ChildrenÕs Hospital, University of Arkansas for Medical Sciences, Little Rock, AR, 3 Pediatric Nephrology, Cincinnati ChildrenÕs Hospital Medical Center, Cincinnati, OH, USA Key words: pediatric – heart transplantation – renal dysfunction – cystatin – neutrophil gelatinase- associated lipocalin Boban P. Abraham, MD, Division of Pediatric Cardiology, Arkansas ChildrenÕs Hospital, 1 ChildrenÕs Way, Slot 512-3, Little Rock, AR 72202. USA Tel.: +501 364 1479 Fax: +501 364 3667 E-mail: bpabraham@uams.edu Accepted for publication 11 February 2011 Abbreviations: BUN, blood urea nitrogen; CKD, chronic kidney disease; CKiD, Chronic Kidney Disease in Children formula; GFR, glomerular filtration rate; KDOQI, Kidney Disease Outcomes Quality Initiative; OHT, orthotopic heart transplant; PHT, pediatric heart transplant; s- and u-NGAL, serum and urine neutrophil gelatinase-associated lipocalin. Pediatr Transplantation 2011: 15: 564–569 Ó 2011 John Wiley & Sons A/S. Pediatric Transplantation DOI: 10.1111/j.1399-3046.2011.01502.x 564