Serum cystatin C in the United States: the Third National Health and Nutrition Examination Survey (NHANES III).
BACKGROUND
Serum cystatin C increasingly is used as a marker of glomerular filtration rate and cardiovascular risk. However, information for serum cystatin C levels in the general population, specifically across a wide age range and different ethnicities, is lacking.


OBJECTIVE
To determine nationally representative serum cystatin C levels, estimate the prevalence of increased cystatin C levels in the general population, and identify factors associated with increased cystatin C levels.


METHODS
Cross-sectional survey.


METHODS
A nationally representative subsample of 7,596 participants aged 12 years or older in the Third National Health and Nutrition Examination Survey conducted in 1988-1994.


METHODS
Age, sex, race/ethnicity, risk factors for chronic kidney disease.


RESULTS
Continuous serum cystatin C levels and serum cystatin C level greater than 1.12 mg/L.


METHODS
Cystatin C was measured in 2006 from stored sera by using an automated particle-enhanced nephelometric assay.


RESULTS
Overall median serum cystatin C level was 0.85 mg/L. Median cystatin C levels increased steeply with age and were greater in males and non-Hispanic white persons, even in a healthy subgroup of 20- to 39-year-olds. Prevalences of increased serum cystatin C levels (>1.12 mg/L) were 1%, 41%, and greater than 50% in all persons aged younger than 20 years, 60 years or older, and 80 years or older. In persons aged 60 years and older, older age, non-Hispanic white ethnicity, hypertension, current smoking, lower levels of education and high-density lipoprotein cholesterol, and increased body mass index, C-reactive protein, and triglyceride values were associated significantly with increased serum cystatin C levels.


CONCLUSIONS
No measured glomerular filtration rate, single measurement of cystatin C, cross-sectional study design.


CONCLUSIONS
Serum cystatin C level is related to sex and ethnicity, even in young healthy individuals. The prevalence of increased cystatin C levels increases dramatically with age, reaching greater than 50% after the age of 80 years in both sexes and all ethnic groups.
Köttgen
Anna
A
Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health and the Welch Center for Prevention, Epidemiology and Clinical Research, Johns Hopkins Medical Institutions, Baltimore, MD 21287, USA.
Selvin
Elizabeth
E
Stevens
Lesley A
LA
Levey
Andrew S
AS
Van Lente
Frederick
F
Coresh
Josef
J
D000328:Adult; D000367:Age Factors; D000368:Aged; D015415:Biomarkers / Q000097:blood*; D003430:Cross-Sectional Studies; D055316:Cystatin C; D015891:Cystatins / Q000097:blood*; D003920:Diabetes Mellitus / Q000097:blood; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D006973:Hypertension / Q000097:blood; D007677:Kidney Function Tests / Q000379:methods*; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D009391:Nephelometry and Turbidimetry; D009749:Nutrition Surveys; D012016:Reference Values; D014481:United States
D015415:Biomarkers; C525030:CST3 protein, human; D055316:Cystatin C; D015891:Cystatins