title: Age, gender, and race effects on cystatin C levels in US adolescents.
abstract: OBJECTIVE
  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.
  
  
  METHODS
  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.
authors.affiliation: Department of Pediatrics, Johns Hopkins School of Medicine, Baltimore, Maryland, USA.
authors.forename: Darcy
authors.initials: D
authors.lastname: Groesbeck
authors.forename: Anna
authors.initials: A
authors.lastname: Köttgen
authors.forename: Rulan
authors.initials: R
authors.lastname: Parekh
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Selvin
authors.forename: George J
authors.initials: GJ
authors.lastname: Schwartz
authors.forename: Josef
authors.initials: J
authors.lastname: Coresh
authors.forename: Susan
authors.initials: S
authors.lastname: Furth
mesh_terms: D000293:Adolescent; D001741:Black or African American / Q000706:statistics & numerical data; D017677:Age Distribution; D000367:Age Factors; D015415:Biomarkers / Q000097:blood; D001806:Blood Urea Nitrogen; D002648:Child; D003404:Creatinine / Q000097:blood; D003430:Cross-Sectional Studies; D055316:Cystatin C / Q000097:blood*; D005260:Female; D006306:Health Surveys; D006801:Humans; D008297:Male; D017058:Mexican Americans / Q000706:statistics & numerical data; D012016:Reference Values; D017678:Sex Distribution; D012737:Sex Factors; D014481:United States; D014527:Uric Acid / Q000097:blood; D044465:White People / Q000706:statistics & numerical data
chemical_list: D015415:Biomarkers; D055316:Cystatin C; D014527:Uric Acid; D003404:Creatinine