Table of Contents

Component Description

Exposure to volatile organic compounds (VOCs) is ubiquitous. Chronic exposure to extremely high levels of some VOCs can lead to cancer and neurocognitive dysfunction. Urinary metabolites of VOCs can be detectable in urine for a longer period of time than the parent VOCs can be detected in blood.

Nearly 200 air toxics have been associated with adverse health effects in occupational studies or laboratory studies, but have not been monitored in general population groups. Information on levels of exposure to these compounds, as measured by their metabolite levels in urine, is essential to determine the need for regulatory mechanisms to reduce the levels of hazardous air pollutants to which the general population is exposed.

Eligible Sample

Examined participants aged 6 years and older from a one-third sample were eligible.

Description of Laboratory Methodology

This method is a quantitative procedure for the measurement of VOC metabolites in human urine using ultra performance liquid chromatography coupled with electrospray tandem mass spectrometry (UPLC-ESI/MSMS) as described by Alwis et. al (2012). Chromatographic separation is achieved using an Acquity UPLC® HSS T3 (Part no. 186003540, 1.8 µm x 2.1 mm x 150 mm, Waters Inc.) column with 15 mM ammonium acetate and acetonitrile as the mobile phases. The eluent from the column is ionized using an electrospray interface to generate and transmit negative ions into the mass spectrometer. Comparison of relative response factors (ratio of native analyte to stable isotope labeled internal standard) with known standard concentrations yields individual analyte concentrations.

Refer to the Laboratory Method Files section for a detailed description of the laboratory methods used.

There were no changes to the lab method, lab equipment, or lab site for this component in the NHANES 2013-2014 cycle.

Laboratory Method Files

Laboratory Quality Assurance and Monitoring

Urine specimens are processed, stored, and shipped to the Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta GA for analysis.

Detailed instructions on specimen collection and processing are discussed in the NHANES Laboratory Procedures Manual (LPM). Vials are stored under appropriate frozen (–20°C) conditions until they are shipped to National Center for Environmental Health for testing.

The NHANES QA/QC protocols meet the 1988 Clinical Laboratory Improvement Act mandates. Detailed QA/QC instructions are discussed in the NHANES LPM.

Mobile Examination Centers (MECs)

Laboratory team performance is monitored using several techniques. NCHS and contract consultants use a structured competency assessment evaluation during visits to evaluate both the quality of the laboratory work and the quality-control procedures. Each laboratory staff member is observed for equipment operation, specimen collection and preparation; testing procedures and constructive feedback are given to each staff member. Formal retraining sessions are conducted annually to ensure that required skill levels were maintained.

Analytical Laboratories

NHANES uses several methods to monitor the quality of the analyses performed by the contract laboratories. In the MEC, these methods include performing second examinations on previously examined participants and blind split samples collected on “dry run” sessions.

NCHS developed and distributed a quality control protocol for all CDC and contract laboratories, which outlined the Westgard rules (Westgard, et al. 1981) used when running NHANES specimens. Progress reports containing any problems encountered during shipping or receipt of specimens, summary statistics for each control pool, QC graphs, instrument calibration, reagents, and any special considerations are submitted to NCHS quarterly. The reports are reviewed for trends or shifts in the data. The laboratories are required to explain any identified areas of concern.

All QC procedures recommended by the manufacturers were followed. Reported results for all assays meet the CDC/NCEH Tobacco and Volatile Branch quality control and quality assurance performance criteria for accuracy and precision, similar to the Westgard rules (Caudill et al., 2008).

Data Processing and Editing

The data were reviewed. Incomplete data or improbable values were sent to the performing laboratory for confirmation.

Analytic Notes

Refer to the 2013-2014 Laboratory Data Overview for general information on NHANES laboratory data.

Subsample Weights

VOC metabolites in urine were assessed in a subsample of participants aged 6 years and older. Use the special one-third weights included in this data file when analyzing data. Special sample weights are required to analyze these data properly. Specific sample weights for this subsample are included in this data file and should be used when analyzing these data.

Demographic and Other Related Variables

The analysis of NHANES laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES 2013-2014 Demographics File contains demographic and sample design variables. The recommended procedure for variance estimation requires use of stratum and PSU variables (SDMVSTRA and SDMVPSU, respectively) in the demographic data file.

This laboratory data file can be linked to the other NHANES data files using the unique survey participant identifier SEQN.

Detection Limits

The detection limits were constant for the analytes in the data set. Two variables are provided for each of these analytes. The variable named ending in “LC” (ex., URDAAMLC) indicates whether the result was below the limit of detection: the value “0” means that the result was at or above the limit of detection, “1” indicates that the result was below the limit of detection. For analytes with analytic results below the lower limit of detection (ex., URDAAMLC=1), an imputed fill value was placed in the analyte results field. This value is the lower limit of detection divided by the square root of 2 (LLOD/sqrt [2]). The other variable prefixed URX (ex., URXAAM) provides the analytic result for the analyte.

The lower limit of detection (LLOD, in µg/L) for urinary VOC metabolites:

VARIABLE Analyte LLOD
URXAAM Urinary N-Acetyl-S-(2-carbamoylethyl)-L-cysteine 2.20
URXAMC Urinary N-Acetyl-S-(N-methylcarbamoyl)-L-cysteine 6.26
URXATC Urinary 2-Aminothiazoline-4-carboxylic acid 15.0
URXBMA Urinary N-Acetyl-S-(benzyl)-L-cysteine 0.500
URXBPM Urinary N-Acetyl-S-(n-propyl)-L-cysteine 1.20
URXCEM Urinary N-Acetyl-S-(2-carboxyethyl)-L-cysteine 6.96
URXCYM Urinary N-Acetyl-S-(2-cyanoethyl)-L-cysteine 0.500
URX1DC Urinary N-Acetyl-S-(1,2-dichlorovinyl)-L-cysteine 12.6
URX2DC Urinary N-Acetyl-S-(2,2-dichlorovinyl)-L-cysteine 4.70
URXDHB Urinary N-Acetyl-S-(3,4-dihydroxybutyl)-L-cysteine 5.25
URXDPM Urinary N-Acetyl-S-(dimethylphenyl)-L-cysteine 0.500
URXGAM Urinary N-Acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine 9.40
URXHEM Urinary N-Acetyl-S-(2-hydroxyethyl)-L-cysteine 0.791
URXHPM Urinary N-Acetyl-S-(3-hydroxypropyl)-L-cysteine 13.0
URXHP2 Urinary N-Acetyl-S-(2-hydroxypropyl)-L-cysteine 5.30
URXPMM Urinary N-Acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine 3.00
URXMAD Urinary Mandelic acid 12.0
URX2MH Urinary 2-Methylhippuric acid 5.00
URX34M Urinary 3- and 4-Methylhippuric acid 8.00
URXMB1 Urinary N-Acetyl-S-(1-hydroxymethyl-2-propenyl)-L-cysteine 0.700
URXMB2 Urinary N-Acetyl-S-(2-hydroxy-3-butenyl)-L-cysteine 0.700
URXMB3 Urinary N-Acetyl-S-(4-hydroxy-2-butenyl)-L-cysteine 0.600
URXPHE Urinary N-Acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine 0.700
URXPHG Urinary Phenylglyoxylic acid 12.0
URXPMA Urinary N-Acetyl-S-(phenyl)-L-cysteine 0.600
URXTCV Urinary N-Acetyl-S-(trichlorovinyl)-L-cysteine 3.00
URXTTC Urinary 2-Thioxothiazolidine-4-carboxylic acid 11.2

Please refer to the NHANES Analytic Guidelines and the on-line NHANES Tutorial for further details on the use of sample weights and other analytic issues.

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 6 YEARS - 150 YEARS

WTSA2YR - Subsample A weights

Variable Name:
WTSA2YR
SAS Label:
Subsample A weights
English Text:
Subsample A weights
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
16284.37488 to 530325.34726 Range of Values 2724 2724
0 No Lab Result 31 2755
. Missing 0 2755

URXUCR - Creatinine, urine (mg/dL)

Variable Name:
URXUCR
SAS Label:
Creatinine, urine (mg/dL)
English Text:
Creatinine, urine (mg/dL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5 to 546 Range of Values 2680 2680
. Missing 75 2755

URX1DC - N-Acel-S-(1,2-dichlorovinl)-L-cys(ng/mL)

Variable Name:
URX1DC
SAS Label:
N-Acel-S-(1,2-dichlorovinl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8.9 to 25.8 Range of Values 2475 2475
. Missing 280 2755

URD1DCLC - N-acel-S-(1,2-dichlorovinl)-L-cys comt

Variable Name:
URD1DCLC
SAS Label:
N-acel-S-(1,2-dichlorovinl)-L-cys comt
English Text:
N-acetyl-S-(1,2-dichlorovinyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2 2
1 Below lower detection limit 2473 2475
. Missing 280 2755

URX2DC - N-acel-S-(2,2-dichlorvinyl)-L-cys(ng/mL)

Variable Name:
URX2DC
SAS Label:
N-acel-S-(2,2-dichlorvinyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2,2-dichlorovinyl)-L-cysteine (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.32 3.32 2551 2551
. Missing 204 2755

URD2DCLC - N-acel-S-(2,2-dichlorvinyl)-L-cys comt

Variable Name:
URD2DCLC
SAS Label:
N-acel-S-(2,2-dichlorvinyl)-L-cys comt
English Text:
N-acetyl-S-(2,2-dichlorovinyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 0 0
1 Below lower detection limit 2551 2551
. Missing 204 2755

URX2MH - 2-methylhippuric acid (ng/mL)

Variable Name:
URX2MH
SAS Label:
2-methylhippuric acid (ng/mL)
English Text:
2-methylhippuric acid (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.54 to 1490 Range of Values 2370 2370
. Missing 385 2755

URD2MHLC - 2-methylhippuric acid comment code

Variable Name:
URD2MHLC
SAS Label:
2-methylhippuric acid comment code
English Text:
2-methylhippuric acid comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2136 2136
1 Below lower detection limit 234 2370
. Missing 385 2755

URX34M - 3-methipurc acd & 4-methipurc acd(ng/mL)

Variable Name:
URX34M
SAS Label:
3-methipurc acd & 4-methipurc acd(ng/mL)
English Text:
3-methylhippuric acid & 4-methylhippuric acid(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5.66 to 14400 Range of Values 2628 2628
. Missing 127 2755

URD34MLC - 3-methipurc acd & 4-methipurc acid comt

Variable Name:
URD34MLC
SAS Label:
3-methipurc acd & 4-methipurc acid comt
English Text:
3-methylhippuric acid & 4-methylhippuric acid comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2609 2609
1 Below lower detection limit 19 2628
. Missing 127 2755

URXAAM - N-ace-S-(2-carbamoylethyl)-L-cys(ng/mL)

Variable Name:
URXAAM
SAS Label:
N-ace-S-(2-carbamoylethyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2-carbamoylethyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1.56 to 2750 Range of Values 2511 2511
. Missing 244 2755

URDAAMLC - N-ace-S-(2-carbamoylethyl)-L-cys comt

Variable Name:
URDAAMLC
SAS Label:
N-ace-S-(2-carbamoylethyl)-L-cys comt
English Text:
N-acetyl-S-(2-carbamoylethyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2508 2508
1 Below lower detection limit 3 2511
. Missing 244 2755

URXAMC - N-ace-S-(N-methlcarbamoyl)-L-cys(ng/mL)

Variable Name:
URXAMC
SAS Label:
N-ace-S-(N-methlcarbamoyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(N-methylcarbamoyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4.43 to 3880 Range of Values 2629 2629
. Missing 126 2755

URDAMCLC - N-ace-S-(N-methlcarbamoyl)-L-cys comt

Variable Name:
URDAMCLC
SAS Label:
N-ace-S-(N-methlcarbamoyl)-L-cys comt
English Text:
N-acetyl-S-(N-methylcarbamoyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2620 2620
1 Below lower detection limit 9 2629
. Missing 126 2755

URXATC - 2-amnothiazolne-4-carbxylic acid(ng/mL)

Variable Name:
URXATC
SAS Label:
2-amnothiazolne-4-carbxylic acid(ng/mL)
English Text:
2-aminothiazoline-4-carboxylic acid(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
10.6 to 2030 Range of Values 2523 2523
. Missing 232 2755

URDATCLC - 2-amnothiazolne-4-carbxylic acid comt

Variable Name:
URDATCLC
SAS Label:
2-amnothiazolne-4-carbxylic acid comt
English Text:
2-amnothiazolne-4-carbxylic acid comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2396 2396
1 Below lower detection limit 127 2523
. Missing 232 2755

URXBMA - N-acetyl-S-(benzyl)-L-cysteine(ng/mL)

Variable Name:
URXBMA
SAS Label:
N-acetyl-S-(benzyl)-L-cysteine(ng/mL)
English Text:
N-acetyl-S-(benzyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.354 to 539 Range of Values 2622 2622
. Missing 133 2755

URDBMALC - N-acetyl-S-(benzyl)-L-cysteine comt

Variable Name:
URDBMALC
SAS Label:
N-acetyl-S-(benzyl)-L-cysteine comt
English Text:
N-acetyl-S-(benzyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2593 2593
1 Below lower detection limit 29 2622
. Missing 133 2755

URXBPM - N-acetyl-S-(n-propyl)-L-cysteine(ng/mL)

Variable Name:
URXBPM
SAS Label:
N-acetyl-S-(n-propyl)-L-cysteine(ng/mL)
English Text:
N-acetyl-S-(n-propyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.85 to 618 Range of Values 2631 2631
. Missing 124 2755

URDBPMLC - N-acetyl-S-(n-propyl)-L-cysteine comt

Variable Name:
URDBPMLC
SAS Label:
N-acetyl-S-(n-propyl)-L-cysteine comt
English Text:
N-acetyl-S-(n-propyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 1810 1810
1 Below lower detection limit 821 2631
. Missing 124 2755

URXCEM - N-acetyl-S- (2-carbxyethyl)-L-cys(ng/mL)

Variable Name:
URXCEM
SAS Label:
N-acetyl-S- (2-carbxyethyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (2-carboxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
4.92 to 4870 Range of Values 2609 2609
. Missing 146 2755

URDCEMLC - N-acetyl-S-(2-carbxyethyl)-L-cys comt

Variable Name:
URDCEMLC
SAS Label:
N-acetyl-S-(2-carbxyethyl)-L-cys comt
English Text:
N-acetyl-S- (2-carboxyethyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2578 2578
1 Below lower detection limit 31 2609
. Missing 146 2755

URXCYM - N-acetyl-S-(2-cyanoethyl)-L-cyst(ng/mL)

Variable Name:
URXCYM
SAS Label:
N-acetyl-S-(2-cyanoethyl)-L-cyst(ng/mL)
English Text:
N-acetyl-S-(2-cyanoethyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.354 to 1640 Range of Values 2576 2576
. Missing 179 2755

URDCYMLC - N-acetyl-S-(2-cyanoethyl)-L-cyst comt

Variable Name:
URDCYMLC
SAS Label:
N-acetyl-S-(2-cyanoethyl)-L-cyst comt
English Text:
N-acetyl-S-(2-cyanoethyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2308 2308
1 Below lower detection limit 268 2576
. Missing 179 2755

URXDHB - N-ace-S- (3,4-dihidxybutl)-L-cys(ng/mL)

Variable Name:
URXDHB
SAS Label:
N-ace-S- (3,4-dihidxybutl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (3,4-dihidroxybutyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.71 to 3280 Range of Values 2639 2639
. Missing 116 2755

URDDHBLC - N-ace-S- (3,4-dihidxybutl)-L-cys comt

Variable Name:
URDDHBLC
SAS Label:
N-ace-S- (3,4-dihidxybutl)-L-cys comt
English Text:
N-acetyl-S- (3,4-dihidroxybutyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2638 2638
1 Below lower detection limit 1 2639
. Missing 116 2755

URXDPM - N-ace-S-(dimethylphenyl)-L-cys(ng/mL)

Variable Name:
URXDPM
SAS Label:
N-ace-S-(dimethylphenyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(dimethylphenyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.354 to 1.93 Range of Values 2471 2471
. Missing 284 2755

URDDPMLC - N-ace-S-(dimethylphenyl)-L-cys comt

Variable Name:
URDDPMLC
SAS Label:
N-ace-S-(dimethylphenyl)-L-cys comt
English Text:
N-acetyl-S-(dimethylphenyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 9 9
1 Below lower detection limit 2462 2471
. Missing 284 2755

URXGAM - N-ac-S-(2-carbmo-2-hydxel)-L-cys(ng/mL)

Variable Name:
URXGAM
SAS Label:
N-ac-S-(2-carbmo-2-hydxel)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6.65 to 246 Range of Values 2636 2636
. Missing 119 2755

URDGAMLC - N-ac-S-(2-carbmo-2-hydxel)-L-cys comt

Variable Name:
URDGAMLC
SAS Label:
N-ac-S-(2-carbmo-2-hydxel)-L-cys comt
English Text:
N-acetyl-S-(2-carbamoyl-2-hydroxyethyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 1073 1073
1 Below lower detection limit 1563 2636
. Missing 119 2755

URXHEM - N-ace-S-(2-hydroxyethyl)-L-cys(ng/mL)

Variable Name:
URXHEM
SAS Label:
N-ace-S-(2-hydroxyethyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(2-hydroxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.559 to 71.8 Range of Values 2586 2586
. Missing 169 2755

URDHEMLC - N-ace-S-(2-hydroxyethyl)-L-cys comt

Variable Name:
URDHEMLC
SAS Label:
N-ace-S-(2-hydroxyethyl)-L-cys comt
English Text:
N-acetyl-S-(2-hydroxyethyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 1191 1191
1 Below lower detection limit 1395 2586
. Missing 169 2755

URXHP2 - N-ace-S-(2-hydroxypropyl)-L-cys(ng/mL)

Variable Name:
URXHP2
SAS Label:
N-ace-S-(2-hydroxypropyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (2-hydroxypropyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3.75 to 6510 Range of Values 2597 2597
. Missing 158 2755

URDHP2LC - N-ace-S-(2-hydroxypropyl)-L-cys comt

Variable Name:
URDHP2LC
SAS Label:
N-ace-S-(2-hydroxypropyl)-L-cys comt
English Text:
N-acetyl-S- (2-hydroxypropyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2431 2431
1 Below lower detection limit 166 2597
. Missing 158 2755

URXHPM - N-ace-S-(3-hydroxypropyl)-L-cys(ng/mL)

Variable Name:
URXHPM
SAS Label:
N-ace-S-(3-hydroxypropyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (3-hydroxypropyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
9.2 to 27400 Range of Values 2606 2606
. Missing 149 2755

URDHPMLC - N-ace-S-(3-hydroxypropyl)-L-cys comt

Variable Name:
URDHPMLC
SAS Label:
N-ace-S-(3-hydroxypropyl)-L-cys comt
English Text:
N-acetyl-S- (3-hydroxypropyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2599 2599
1 Below lower detection limit 7 2606
. Missing 149 2755

URXMAD - Mandelic acid(ng/mL)

Variable Name:
URXMAD
SAS Label:
Mandelic acid(ng/mL)
English Text:
Mandelic acid(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8.5 to 2040 Range of Values 2541 2541
. Missing 214 2755

URDMADLC - Mandelic acid comment code

Variable Name:
URDMADLC
SAS Label:
Mandelic acid comment code
English Text:
Mandelic acid comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2482 2482
1 Below lower detection limit 59 2541
. Missing 214 2755

URXMB1 - N-A-S-(1-hydrxMet)-2-Prpn)-L-cys(ng/mL)

Variable Name:
URXMB1
SAS Label:
N-A-S-(1-hydrxMet)-2-Prpn)-L-cys(ng/mL)
English Text:
N-acetyl-S-(1-hydroxyMethyl)-2-Propenyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.495 to 1.56 Range of Values 2587 2587
. Missing 168 2755

URDMB1LC - N-A-S-(1-hydrxmet)-2-Prpn)-L-cys comt

Variable Name:
URDMB1LC
SAS Label:
N-A-S-(1-hydrxmet)-2-Prpn)-L-cys comt
English Text:
N-acetyl-S-(1-hydroxymethyl)-2-Propenyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 14 14
1 Below lower detection limit 2573 2587
. Missing 168 2755

URXMB2 - N-Ac-S-(2-hydrxy-3-butnyl)-L-cys(ng/mL)

Variable Name:
URXMB2
SAS Label:
N-Ac-S-(2-hydrxy-3-butnyl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (2-hydroxy-3-butenyl)-L-cysteine (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.495 to 17.4 Range of Values 2627 2627
. Missing 128 2755

URDMB2LC - N-Ac-S-(2-hydrxy-3-butnyl)-L-cys comt

Variable Name:
URDMB2LC
SAS Label:
N-Ac-S-(2-hydrxy-3-butnyl)-L-cys comt
English Text:
N-acetyl-S- (2-hydroxy-3-butenyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 272 272
1 Below lower detection limit 2355 2627
. Missing 128 2755

URXMB3 - N-A-S-(4-hydrxy-2butn-l-yl)-L-cys(ng/mL)

Variable Name:
URXMB3
SAS Label:
N-A-S-(4-hydrxy-2butn-l-yl)-L-cys(ng/mL)
English Text:
N-acetyl-S- (4-hydroxy-2-butenyl)-L-cysteine (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.424 to 264 Range of Values 2520 2520
. Missing 235 2755

URDMB3LC - N-A-S-(4-hydrxy-2butn-l-yl)-L-cys comt

Variable Name:
URDMB3LC
SAS Label:
N-A-S-(4-hydrxy-2butn-l-yl)-L-cys comt
English Text:
N-acetyl-S- (4-hydroxy-2-butenyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2480 2480
1 Below lower detection limit 40 2520
. Missing 235 2755

URXPHE - N-ace-S-(phenl-2-hydxyetl)-L-cys(ng/mL)

Variable Name:
URXPHE
SAS Label:
N-ace-S-(phenl-2-hydxyetl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.495 to 82.1 Range of Values 2569 2569
. Missing 186 2755

URDPHELC - N-ace-S-(phenl-2-hydxyetl)-L-cys comt

Variable Name:
URDPHELC
SAS Label:
N-ace-S-(phenl-2-hydxyetl)-L-cys comt
English Text:
N-acetyl-S-(phenyl-2-hydroxyethyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 922 922
1 Below lower detection limit 1647 2569
. Missing 186 2755

URXPHG - Phenylglyoxylic acid(ng/mL)

Variable Name:
URXPHG
SAS Label:
Phenylglyoxylic acid(ng/mL)
English Text:
Phenylglyoxylic acid(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
8.5 to 2160 Range of Values 2575 2575
. Missing 180 2755

URDPHGLC - Phenylglyoxylic acid comment code

Variable Name:
URDPHGLC
SAS Label:
Phenylglyoxylic acid comment code
English Text:
Phenylglyoxylic acid comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2553 2553
1 Below lower detection limit 22 2575
. Missing 180 2755

URXPMA - N-acetyl-S-(phenyl)-L-cysteine(ng/mL)

Variable Name:
URXPMA
SAS Label:
N-acetyl-S-(phenyl)-L-cysteine(ng/mL)
English Text:
N-acetyl-S-(phenyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.424 to 28.3 Range of Values 2561 2561
. Missing 194 2755

URDPMALC - N-acetyl-S-(phenyl)-L-cysteine comt

Variable Name:
URDPMALC
SAS Label:
N-acetyl-S-(phenyl)-L-cysteine comt
English Text:
N-acetyl-S-(phenyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 969 969
1 Below lower detection limit 1592 2561
. Missing 194 2755

URXPMM - N-A-S-(3-hydrxprpl-1-metl)-L-cys(ng/mL)

Variable Name:
URXPMM
SAS Label:
N-A-S-(3-hydrxprpl-1-metl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2.12 to 20800 Range of Values 2593 2593
. Missing 162 2755

URDPMMLC - N-A-S-(3-hydrxprpl-1-metl)-L-cys comt

Variable Name:
URDPMMLC
SAS Label:
N-A-S-(3-hydrxprpl-1-metl)-L-cys comt
English Text:
N-acetyl-S-(3-hydroxypropyl-1-methyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 2592 2592
1 Below lower detection limit 1 2593
. Missing 162 2755

URXTCV - N-acetyl-S-(trichlorovinyl)-L-cys(ng/mL)

Variable Name:
URXTCV
SAS Label:
N-acetyl-S-(trichlorovinyl)-L-cys(ng/mL)
English Text:
N-acetyl-S-(trichlorovinyl)-L-cysteine(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2.12 2.12 2619 2619
. Missing 136 2755

URDTCVLC - N-acetyl-S-(trichlorovinyl)-L-cys comt

Variable Name:
URDTCVLC
SAS Label:
N-acetyl-S-(trichlorovinyl)-L-cys comt
English Text:
N-acetyl-S-(trichlorovinyl)-L-cysteine comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 0 0
1 Below lower detection limit 2619 2619
. Missing 136 2755

URXTTC - 2-thoxothazlidne-4-carbxylic acid(ng/mL)

Variable Name:
URXTTC
SAS Label:
2-thoxothazlidne-4-carbxylic acid(ng/mL)
English Text:
2-thioxothiazolidine-4-carboxylic acid(ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7.9 to 1130 Range of Values 2640 2640
. Missing 115 2755

URDTTCLC - 2-thoxothazlidne-4-carbxylic comt

Variable Name:
URDTTCLC
SAS Label:
2-thoxothazlidne-4-carbxylic comt
English Text:
2-thioxothiazolidine-4-carboxylic acid comment code
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 At or above the detection limit 927 927
1 Below lower detection limit 1713 2640
. Missing 115 2755