Table of Contents

Locator Record

Title: Urinary Phytoestrogens (PHYTO_E )
Contact Number: 1-866-441-NCHS
Years of Content: 2007 - 2008
First Published: July, 2012
Revised: NA
Access Constraints: None
Use Constraints: None
Geographic Coverage: National
Subject:Urinary Phytoestrogens
Record Source: NHANES 2007 - 2008
Survey Methodology: NHANES 2007 - 2008 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

Phytoestrogens are plant-derived polyphenolic compounds, such as isoflavones and lignans that are structurally similar to endogenous estrogens (Cornwell, et al. 2004). Phytoestrogens are capable of estrogen-receptor binding  (Cornwell et al., 2004) and may also influence other biologic pathways. The consumption of diets high in phytoestrogen-rich foods has been associated with lower rates of hormone-dependent cancers (Peeters et al., 2003; Adlercreutz et al., 2002; Davis et al., 1999), improved bone health (Ma et al., 2007; Coxam et al., 2003) and other healthy outcomes. Biomeasures of phytoestrogens are necessary to establish reference ranges for these compounds and to evaluate their potential effects on human health.

 

Eligible Sample

Participants aged 6 years and older who met the subsample requirements.

Description of Laboratory Methodology

The test principle utilizes high performance liquid chromatography-atmospheric pressure photoionization-tandem mass spectrometry (HPLC-APPI-MS/MS) for the quantitative detection of genistein, daidzein, equol, O-desmethylangolensin, enterodiol, and enterolactone. Human urine samples are processed using enzymatic deconjugation of the glucuronidated phytoestrogens followed by size-exclusion filtration. Phytoestrogens are then separated from other urine components by reversed phase HPLC, detected by APPI-MS/MS, and quantified by isotope dilution. Assay precision is improved by incorporating carbon-13 labeled internal standards for each of the analytes, as well as a 4-methylumbelliferyl glucuronide and 4-methylumbelliferyl sulfate standards to monitor deconjugation efficiency. This selective method allows for rapid detection of phytoestrogens in human urine with limits of detection in the low parts per billion (ng/mL) range.

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 for analysis.

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

Mobile Examination Centers (MECs)

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

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

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 blind split samples collected on “dry run” sessions. In addition, contract laboratories randomly perform repeat testing on 2.0% of all specimens.

NCHS developed and distributed a quality control protocol for all the contract laboratories which outlined the Westgard rules 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 and Westat 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 Division of Environmental Health Laboratory Sciences’ quality control and quality assurance performance criteria for accuracy and precision (similar to specifications outlined by Westgard (1981).

Analytic Notes

Subsample weights

Measures of urinary environmentals were measured in a one third subsample of persons 6 years and over. Special sample weights (WTSB2YR) 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.

Variance estimation

The analysis of NHANES  laboratory data must be conducted with the key survey design and basic demographic variables. The NHANES  Demographic Data 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.

Links to NHANES Data Files

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 all of the analytes in the data set. Two variables are provided for each of these analytes. The variable named URD___LC indicates whether the result was below the limit of detection. There are two values: “0” and “1”. “0” means that the result was at or above the limit of detection. “1” indicates that the result was below the limit of detection.

 The other variables named URX___ provide the analytic result for that analyte.

Urinary Phytoestrogens: Limit of Detection in nanogram/milliliter
 Analyte  SAS Variable  LOD (ng/mL)
 Daidzein  URXDAZ  0.4
 Enterodiol  URXETD  0.04
 Enterolactone   URXETL  0.1
 Equol  URXEQU  0.06
 Genistein  URXGNS  0.2
 O-Desmethylangolensin  URXDMA  0.2

 

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

WTSB2YR - Environmental B 2 year weights

Variable Name:
WTSB2YR
SAS Label:
Environmental B 2 year weights
English Text:
Environmental B 2 year weights
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 to 533131.16757 Range of Values 2718 2718
. Missing 0 2718

URXDAZ - Daidzein (ng/mL)

Variable Name:
URXDAZ
SAS Label:
Daidzein (ng/mL)
English Text:
Daidzein (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.3 to 33000 Range of Values 2424 2424
. Missing 294 2718

URDDAZLC - Daidzein comment code

Variable Name:
URDDAZLC
SAS Label:
Daidzein comment code
English Text:
Daidzein 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 2422 2422
1 Below lower detection limit 2 2424
. Missing 294 2718

URXDMA - O-Desmethylangolensin (O-DMA) (ng/mL)

Variable Name:
URXDMA
SAS Label:
O-Desmethylangolensin (O-DMA) (ng/mL)
English Text:
O-Desmethylangolensin (O-DMA) (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 21600 Range of Values 2424 2424
. Missing 294 2718

URDDMALC - O-DMA comment code

Variable Name:
URDDMALC
SAS Label:
O-DMA comment code
English Text:
O-DMA 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 2259 2259
1 Below lower detection limit 165 2424
. Missing 294 2718

URXEQU - Equol (ng/mL)

Variable Name:
URXEQU
SAS Label:
Equol (ng/mL)
English Text:
Equol (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.04 to 15200 Range of Values 2424 2424
. Missing 294 2718

URDEQULC - Equol comment code

Variable Name:
URDEQULC
SAS Label:
Equol comment code
English Text:
Equol 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 2418 2418
1 Below lower detection limit 6 2424
. Missing 294 2718

URXETD - Enterodiol (ng/mL)

Variable Name:
URXETD
SAS Label:
Enterodiol (ng/mL)
English Text:
Enterodiol (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.03 to 36100 Range of Values 2424 2424
. Missing 294 2718

URDETDLC - Enterodiol comment code

Variable Name:
URDETDLC
SAS Label:
Enterodiol comment code
English Text:
Enterodiol 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 2408 2408
1 Below lower detection limit 16 2424
. Missing 294 2718

URXETL - Enterolactone (ng/mL)

Variable Name:
URXETL
SAS Label:
Enterolactone (ng/mL)
English Text:
Enterolactone (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 105000 Range of Values 2424 2424
. Missing 294 2718

URDETLLC - Enterolactone comment code

Variable Name:
URDETLLC
SAS Label:
Enterolactone comment code
English Text:
Enterolactone 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 2418 2418
1 Below lower detection limit 6 2424
. Missing 294 2718

URXGNS - Genistein (ng/mL)

Variable Name:
URXGNS
SAS Label:
Genistein (ng/mL)
English Text:
Genistein (ng/mL)
Target:
Both males and females 6 YEARS - 150 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.1 to 11000 Range of Values 2424 2424
. Missing 294 2718

URDGNSLC - Genistein comment code

Variable Name:
URDGNSLC
SAS Label:
Genistein comment code
English Text:
Genistein 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 2423 2423
1 Below lower detection limit 1 2424
. Missing 294 2718

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 490 Range of Values 2623 2623
. Missing 95 2718