Table of Contents

Locator Record

Title: Second Day Exam - Urine Creatinine and Albumin (L16_2_B )
Contact Number: 1-866-441-NCHS
Years of Content: 2001 - 2002
First Published: September, 2010
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Second Day Exam - Urine Creatinine and Albumin
Record Source: NHANES 2001 - 2002
Survey Methodology: NHANES 2001 - 2002 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

Second Day Exams


See the general documentation on Second Day laboratory exams
. See the general documentation on second day laboratory exams. Also, see the documentation for the primary exam data for Laboratory 16.

Urinary albumin and creatinine were measured.

Eligible Sample

Participants aged 16-69 years were tested.

Description of Laboratory Methodology

Urinary creatinine

Creatinine analysis uses a Jaffé rate reaction, in which creatinine reacts with picrate in an alkaline solution to form a red creatinine-picrate complex. The reaction is measured with a CX3 analyzer. The rate of the color development is measured 25.6 sec after sample injection at 520 nm and at 560 nm. The rate difference between the two wavelengths is proportional to the concentration of creatinine in the reaction cup. The procedures described below are the standard protocols of the Fairview University Medical Center (FUMC).

Creatinine, derived from creatine, is released into the plasma at a relatively constant rate. The amount of creatinine per unit of muscle mass is constant; therefore, creatinine is the best indicator of impaired kidney function.

Urinary albumin

A solid-phase fluorescent immunoassay for the measurement of human urinary albumin is described by Chavers et al. The fluorescent immunoassay is a noncompetitive, double-antibody method for the determination of human albumin in urine. Antibody to human albumin is covalently attached to derivatized polyacrylamide beads. The solid-phase antibody is reacted with a urine specimen. The urine albumin-antigen complexes with the solid-phase antibody.

This complex then reacts with fluorescein-labeled antibody. The
unattached fluorescent antibody is removed by washing during centrifugation. The fluorescence of the stable solid-phase antibody complex with a fluorometer. The fluorescence is directly proportional to the amount of urine albumin present. The standard curve is 0.5-20 µg/mL albumin.

Increased microalbuminuria is a sign of renal disease and may be predictive of nephropathy risk in patients with insulin-dependent diabetes. Results of the fluorescent immunoassay (FIA) are reproducible, and the test is accurate and sensitive for the detection of human urinary albumin excretion. It is especially useful for measurement of low levels of urinary albumin not detectable by dipstick methods. The FIA assay resembles the radio-immunoassay (RIA) in technique and sensitivity without the potential health hazards associated with the handling of isotopes in the laboratory.

Data Processing and Editing

Urine specimens were processed, stored and shipped to University of Minnesota, Minneapolis, Minnesota for analysis. Detailed specimen collection and processing instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Read the LABDOC file for detailed data processing and editing protocols. The analytical methods are described in the Description of the Laboratory Methodology section.

Laboratory Quality Assurance and Monitoring

The NHANES quality control and quality assurance protocols (QA/QC) meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed quality control and quality assurance instructions are discussed in the NHANES Laboratory/Medical Technologists Procedures Manual (LPM). Read the LABDOC file for detailed QA/QC protocols.

Analytic Notes

The second day exam data was a convenience sample and thus did not have sample weights. The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES Household Questionnaire Data Files contain demographic data, health indicators, and other related information collected during household interviews. The Phlebotomy Examination File includes auxiliary information such as the conditions precluding venipuncture. The Household Questionnaire Data Files and Phlebotomy Examination File may be linked to the laboratory data file using the unique survey participant identifier SEQN.

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 16 YEARS - 69 YEARS

LB2DAY - Days between 1st and 2nd exam

Variable Name:
LB2DAY
SAS Label:
Days between 1st and 2nd exam
English Text:
The number of days between the collection of the first and second exam
Target:
Both males and females 16 YEARS - 69 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3 to 47 Range of Values 549 549
. Missing 6 555

UR2UCR - Creatinine, urine (mg/dL)

Variable Name:
UR2UCR
SAS Label:
Creatinine, urine (mg/dL)
English Text:
Creatinine, urine (mg/dL)
Target:
Both males and females 16 YEARS - 69 YEARS
Hard Edits:
0 to 999999
Code or Value Value Description Count Cumulative Skip to Item
11 to 554 Range of Values 549 549
. Missing 6 555

UR2UCRSI - Creatinine, urine (umol/L)

Variable Name:
UR2UCRSI
SAS Label:
Creatinine, urine (umol/L)
English Text:
Creatinine, urine (umol/L)
Target:
Both males and females 16 YEARS - 69 YEARS
Hard Edits:
0 to 999999
Code or Value Value Description Count Cumulative Skip to Item
972 to 48974 Range of Values 549 549
. Missing 6 555

UR2UMA - Albumin, urine (ug/mL)

Variable Name:
UR2UMA
SAS Label:
Albumin, urine (ug/mL)
English Text:
Albumin, urine (ug/mL)
Target:
Both males and females 16 YEARS - 69 YEARS
Hard Edits:
0 to 99999.9
Code or Value Value Description Count Cumulative Skip to Item
0.5 to 3340 Range of Values 549 549
. Missing 6 555

UR2UMASI - Albumin, urine (mg/L) SI

Variable Name:
UR2UMASI
SAS Label:
Albumin, urine (mg/L) SI
English Text:
Albumin, urine (mg/L) SI
Target:
Both males and females 16 YEARS - 69 YEARS
Hard Edits:
0 to 99999.9
Code or Value Value Description Count Cumulative Skip to Item
0.5 to 3340 Range of Values 549 549
. Missing 6 555