Table of Contents

Locator Record

Title: Cystatin C (Surplus Sera) (SSCYST_A )
Contact Number: 1-866-441-NCHS
Years of Content: 1999 - 2000
First Published: June, 2008
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Cystatin C
Record Source: NHANES 1999 - 2000
Survey Methodology: NHANES 1999 - 2000 is a stratified multistage probability sample of the civilian non-institutionalized population of the U.S.
Medium: NHANES Web site; SAS transport files

Component Description

Cystatin C assayed from stored serum samples from NHANES 1999-2000.

Eligible Sample

All participants aged 60+ with available specimen and a 25% random sample of participants aged 12-59 years. This younger group is supplemented with all individuals with high serum creatinine 1.2 mg/dl in men and >1.0 mg/dl in women) after calibration.

Description of Laboratory Methodology

All assays were conducted using the Dade Behring N Latex Cystatin C assay which is an automated particle-enhanced nephelometric assay (PENIA) run on the Dade Behring Nephelometer II (BNII) (1).

Data Processing and Editing

All data will be made publicly available.

Laboratory Quality Assurance and Monitoring

This assay has an intra-assay imprecision of 2.0 - 3.0% coefficient of variation and an inter-assay imprecision of 3.2 - 4.4% coefficient of variation. The assay range is 0.23 - 7.25 mg/dL. A thorough review of different assay methodologies by Newman (2) concluded that it is the most precise automated assay across the clinical concentration range and performed slightly better than the other automated assays in terms of sensitivity and lack of analytical interference.

Analytic Notes

The sub-sample of participants aged 12-59 requires modification of original sampling weights. Weights will be provided by investigators to NCHS and will be adjusted by age, sex, race, and serum creatinine strata to match the original NHANES 1999-2000 design.

Acknowledgement

This research was supported by NIH grants UO1 DK 053869, UO1 DK 067651, and UO1 DK 35073. 

References

Codebook and Frequencies

SEQN - Respondent sequence number

Variable Name:
SEQN
SAS Label:
Respondent sequence number
English Text:
Respondent sequence number.
Target:
Both males and females 12 YEARS - 150 YEARS

SSCYPC - Cystatin C (mg/L)

Variable Name:
SSCYPC
SAS Label:
Cystatin C (mg/L)
English Text:
Cystatin C (mg/L)
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.47 to 7.15 Range of Values 2714 2714
. Missing 38 2752

WTSCY4YR - Surplus sera cystatin 99-02 weights

Variable Name:
WTSCY4YR
SAS Label:
Surplus sera cystatin 99-02 weights
English Text:
Surplus sera cystatin 99-02 weights
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 418199.9809 Range of Values 2752 2752
. Missing 0 2752