Received February 19, 2008
Accepted on July 14, 2008

ORIGINAL ARTICLES

Age, Gender, and Race Effects on Cystatin C Levels in US Adolescents

Darcy Groesbeck ^*, Anna Köttgen , Rulan Parekh ^*, Elizabeth Selvin , George J. Schwartz ^||, Josef Coresh , and Susan Furth ^*1

*Department of Pediatrics, Johns Hopkins School of Medicine, Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Welch Center for Prevention, Epidemiology, and Clinical Research, and Department of Medicine, Johns Hopkins Hospital, Baltimore, Maryland; and ||Department of Pediatrics, University of Rochester School of Medicine, Rochester, New York

¹ To whom correspondence should be addressed. E-mail: sfurth{at}jhmi.edu.

	Abstract

Background and objectives: The objective of this study was to describe the normal range of serum cystatin C and identify factors associated with variability in serum cystatin C contrasting with factors that are known to influence creatinine levels in the general US adolescent population.

Design, setting, participants, & measurements: Serum cystatin C and creatinine were measured in 719 participants aged 12 to 19 yr in the Third National Health and Nutrition Examination Survey, a national cross-sectional survey conducted in 1988 through 1994. We calculated gender- and race/ethnicity-specific cystatin C and creatinine ranges and conducted multivariable linear regression analyses to assess factors that contribute to variability in cystatin C and creatinine levels.

Results: Overall, the mean serum cystatin C level was 0.84 mg/L and was higher in male than female individuals and higher in non-Hispanic white versus non-Hispanic black and Mexican American individuals. The mean serum creatinine was 0.71 mg/dl and was higher in male than in female individuals but lower in non-Hispanic white and Mexican American compared with non-Hispanic black individuals. Unlike creatinine, which increases with age from 12 to 19 yr, cystatin C levels decrease, particularly in female individuals. After adjustment for age, gender, and race/ethnicity, uric acid and blood urea nitrogen were significantly associated with cystatin C levels.

Conclusions: Serum cystatin C is significantly related to gender, age, race/ethnicity, uric acid, and blood urea nitrogen in adolescents.