Table of Contents

Locator Record

Title: Cystatin C, β-trace Protein & β2 Microglobulin (NHANES III Second Examination Surplus Sera) (SSNH3CYS )
Contact Number: 1-866-441-NCHS
Years of Content: 1988 - 1994
First Published: April, 2012
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Cystatin C, β-trace Protein & β2 Microglobulin (NHANES III Second Examination Surplus Sera)
Record Source: NHANES 1988 - 1994
Survey Methodology: NHANES 1988 - 1994 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, β-trace protein (BTP) and β2 microglobulin (B2M) assayed from stored surplus serum samples from the NHANES III Second Examination (1988-1994).

Eligible Sample

Cystatin C, BTP, and B2M were measured in a subsample of stored surplus serum samples obtained from NHANES III Second Examination participants aged 12 years or older who had previous measurements of cystatin C conducted in First Examination NHANES III samples.

Description of Laboratory Methodology

Cystatin C, BTP and B2M were measured in 2009 at the University of Minnesota (1, 2). Cystatin C measurements were conducted using the Siemens (formerly Dade Behring) N Latex Cystatin C assay, an automated particle-enhanced nepholometric assay (Siemens Diagnostics). BTP was assayed using the N Latex β-trace protein assay (Siemens Diagnostics). B2M was assayed using the N Latex β2 microglobulin assay (Siemens Diagnostics).

Data Processing and Editing

All data have been made publicly available.

Laboratory Quality Assurance and Monitoring

The inter-assay coefficients of variation for the cystatin C, βTP and β2M assays were 4.0% (mean 0.698 mg/L), 5.7% (mean 0.594 mg/L) and 2.7% (mean 1.757 mg/L), respectively.

Analytic Notes

The Second Examination of NHANES III is a convenience sample of the larger NHANES III population and no sample weights are applied to this subsample. Cystatin C calibration has varied substantially across laboratories between 2006—when the original NHANES III (First Examination) cystatin C stored surplus sera study was conducted —and 2009—when the present measurements were conducted. Due to differences in laboratory calibration of assays, there are systematic differences in the cystatin C values from the First Examination and those from the Second Examination and other NHANES surveys. Users need to consider the shift in laboratories when comparing cystatin C measurements from the Second Examination samples to measurements from the First Examination and other NHANES samples, conducted at different time points.

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

SSB2MR - Beta-2 microglobulin (mg/L) - REPEAT

Variable Name:
SSB2MR
SAS Label:
Beta-2 microglobulin (mg/L) - REPEAT
English Text:
Beta-2 microglobulin (mg/L) - REPEAT
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.943 to 65.7 Range of Values 873 873
. Missing 3 876

SSBTPR - Beta-trace protein (mg/L) - REPEAT

Variable Name:
SSBTPR
SAS Label:
Beta-trace protein (mg/L) - REPEAT
English Text:
Beta-trace protein (mg/L) - REPEAT
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.187 to 17 Range of Values 873 873
. Missing 3 876

SSCYSCR - Cystatin C (mg/L) - REPEAT

Variable Name:
SSCYSCR
SAS Label:
Cystatin C (mg/L) - REPEAT
English Text:
Cystatin C (mg/L) - REPEAT
Target:
Both males and females 12 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.398 to 6.58 Range of Values 873 873
. Missing 3 876