Table of Contents

Component Description

Users of the 2011-2012 dual-energy X-ray absorptiometry whole body data (DXX_G) are encouraged to read the documentation before accessing the data file.

Dual-energy x-ray absorptiometry (DXA) is the most widely accepted method of measuring body composition due in part to its speed, ease of use, and low radiation exposure (Baran, 1997; Genant, 1996; Heymsfield, 1989; and Njeh, 1999). Whole body DXA scans were administered from 1999-2006 and 2011-12. The NHANES DXA examination provides nationally representative data on body composition (bone and soft tissue), overall, and for age, gender, and race/ethnic groups, to study the association between body composition and other health conditions and risk factors, such as cardiovascular disease, diabetes, hypertension, and physical activity and dietary intake patterns.

The DXA scans provide bone and soft tissue measurements for the total body, for both arms and both legs, the trunk, and the head. Bone measurements also were obtained for the pelvis, left and right ribs, thoracic spine, and lumbar spine. Values for the total body and regions include:

 

Eligible Sample

DXA scans were administered to eligible survey participants aged 8-59. Pregnant females were excluded from the DXA examination. Participants who were excluded from the DXA examination for reasons other than pregnancy were considered to be eligible nonrespondents. Reasons for exclusion from the DXA examination were as follows:

 

The variable DXAEXSTS indicates the examination status for the whole body scan. The codes for DXAEXSTS are as follows:

DXAEXSTS – whole body scan examination status variable
1 = Whole body scan completed, and all regions are valid
2 = Whole body scan completed, but one or more regions are invalid
3 = Whole body not scanned, pregnancy
4 = Whole body not scanned, weight > 450 lbs
5 = Whole body not scanned, height > 6’5”
6 = Whole body not scanned, other reason

The main reasons for completed, but invalid, whole body scans were an insufficient scan area or partial scan. The “Not scanned, other reason” code includes no time to complete the examination, pregnancy test not completed, and participant refusal, as well as exclusion for reasons other than pregnancy, such as a medical test.

Protocol and Procedure

The whole body scans were acquired on Hologic Discovery model A densitometers (Hologic, Inc., Bedford, Massachusetts), using software version Apex 3.2. The radiation exposure from DXA whole body scans is extremely low at less than 20 uSv. All scans in the DXX_G file were analyzed with Hologic APEX version 4.0 software with NHANES BCA option.

The DXA examinations were administered by trained and certified radiology technologists. Further details of the DXA examination protocol are documented in the Body Composition Procedures Manual located on the NHANES website

Quality Assurance & Quality Control

A high level of quality control was maintained throughout the DXA data collection and scan analysis, including a rigorous phantom scanning schedule.

Monitoring of Field Staff and Densitometers
Staff from the National Center for Health Statistics (NCHS) and the NHANES data collection contractor monitored technologist acquisition performance through in-person observations in the field. Retraining sessions were conducted with the technologists annually and as needed to reinforce correct techniques and appropriate protocol. In addition, technologist performance codes were recorded by the NHANES quality control center at the University of California, San Francisco (UCSF), Department of Radiology, during review of participant scans. The codes documented when the technologist had deviated from acquisition procedures and where scan quality could have been improved. The performance codes were tracked for each technologist individually and a summary was reported to NCHS on a quarterly basis. Additional feedback on technologist performance was provided by the UCSF when problems were noted during review of the scans. Ongoing communication was maintained throughout the year among the UCSF, the NCHS, and the data collection contractor regarding any issues that arose.

Hologic service engineers performed all routine densitometer maintenance and repairs. Copies of all reports completed by the manufacturer’s service engineers were sent to the UCSF when the scanners were serviced or repaired so any changes in measurement as a result of the work could be assessed.

Scan Analysis
Each participant scan and phantom scan was reviewed and analyzed by the UCSF using standard radiologic techniques and study-specific protocols developed for NHANES. The Hologic software, APEX v4.0 (Hologic) was used to analyze whole body scans acquired in 2011-12. Expert review was conducted by the UCSF on 100% of analyzed participant scans to verify the accuracy and consistency of the results.

Invalidity Codes
Invalidity codes were applied by the UCSF to indicate the reasons that regions of the body could not be analyzed accurately. The invalidity codes are provided in the data file (see the Data Processing and Editing section for a more detailed description of the invalidity codes).

Quality Control Scans
The quality control phantoms were scanned according to a predetermined schedule. The Hologic Anthropomorphic Spine Phantom that traveled with each MEC was scanned daily, as required by the manufacturer, to ensure accurate calibration of the densitometer. Other MEC-specific phantoms, such as the Hologic Whole Body Slim-line Phantom and Hologic Tissue Step Phantom, were scanned 1 to 3 times weekly. A Hologic Spine (HSP-Q96) Phantom, Hologic Block, and Hologic whole body Phantoms circulated among the MECs and were scanned at the start of operations at each survey site.

Air scans, phantom-less scans using the whole body scan mode, were used to describe and monitor the systems’ radiographic uniformity across the entire scan field. Poor uniformity could be caused by poor aperture alignment, incorrect gantry rotation, non-uniform gain in detectors, etc., that result in localized inaccuracies in the attenuation values.

The complete phantom scanning schedule is described in the Body Composition Procedures Manual located on the NHANES website.

In 2011-2012, longitudinal monitoring was conducted through daily spine phantom scans as required by the manufacturer, 3 times weekly whole body slim-line phantom scans and air scans in order to correct any scanner-related changes in participant data. The circulating HSP-Q96, block and whole body phantoms, which were scanned at the start of operations at each site, provided additional data for use in longitudinal monitoring and cross calibration.

The UCSF used the Cumulative Statistics method (CUSUM) and the MEC-specific phantom data to determine breaks in the calibration of the densitometers over the course of the survey (Lu, 1996). Multiplicative correction factors were used to correct the phantom data back to the baseline calibration. The type, frequency, and magnitude of calibration problems detected in the NHANES data were similar to those in other studies using stationary densitometers that were being monitored by UCSF.

After applying the correction factors developed by UCSF from the cross-calibration and longitudinal phantom data to the NHANES participant data, the adjusted participant data were compared to unadjusted data. The magnitude of the changes and reduction in standard errors between the adjusted and unadjusted data were found to be small and correction of the participant data not required.

A number of data quality issues were addressed through the quality control program. Direct feedback given to the technologists regarding acquisition problems affecting the quality of the scans and yearly refresher training resulted in improved technologist performance. The rigorous schedule of quality control scans provided continuous monitoring of machine performance. The expert review procedures helped to ensure that scan analysis was accurate and consistent.

Data Processing and Editing

During the editing process, data were reviewed for completeness, consistency, and outliers. Back-end edits of the data were performed when errors were identified. The NHANES BCA option was enabled for whole body scan analysis, this option adds 5% of lean mass to the fat mass. The correction is based on the results of an analysis of QDR- 4500A DXA data from seven research laboratories indicating that the QDR-4500A algorithm underestimated fat mass and overestimated lean mass (Schoeller, 2005).

Invalidity Codes
Invalidity codes were included in the data file to indicate the reasons that regions of the body could not be analyzed accurately. Invalidity codes were applicable to completed scans only (DXAEXSTS= 1 or 2). If a participant was not scanned, all invalidity codes are missing.

The invalidity codes are provided in the data file as follows:

Invalidity codes
DXAHEBV = head bone
DXAHETV = head tissue
DXALABV = left arm bone
DXALATV = left arm tissue
DXALLBV = left leg bone
DXALLTV = left leg tissue
DXARABV = right arm bone
DXARATV = right arm tissue
DXARLBV = right leg bone
DXARLTV = right leg tissue
DXATRBV = trunk bone, includes thoracic and lumbar spine, left and right ribs, and pelvis
DXATRTV = trunk tissue

Values for invalidity codes DXAHEBV and DXAHETV:
0 = Valid data
1 = Removable or non-removable objects
5 = Body parts out of scan region
6 = Positioning problem
7 = Other

Values for invalidity codes DXALABV, DXALATV, DXARABV, DXARATV, DXALLBV, DXALLTV, DXARLBV and DXARLTV:
0 = Valid data
1 = Removable or non-removable objects
4= Arm/leg overlap
5= Body parts out of scan region
6= Positioning problem
7= Other

Values for invalidity codes DXATRBV and DXATRTV:
0 = Valid data
1 = Removable or non-removable objects
3 = Excessive x-ray noise due to morbid obesity
4= Arm/leg overlap
5= Body parts out of scan region
6= Positioning problem
7= Other

If any region was coded as invalid all bone and soft tissue measurements for that region were set to missing.

The percentage of eligible survey participants in 2011-2012 with 100% valid data (all analyzed regions were valid) is shown by age group in Table 1. The percentage of participants with valid data decreases with increasing age. The decrease in valid data with age was due primarily to an increase in the number of participants with implants, such as stents and hip replacements and higher rates of obesity resulting in invalid truncal data from “obesity noise.” The percentage of participants with 100% valid data also decreases with increasing BMI due to weight over 450 pounds and “obesity noise” (Table 2).

Table 1. Percentages of interviewed and examined participants 8-59 years of age with valid DXA data by age group, NHANES 2011-12.
Age group (years) Interviewed and Examined (N)* Eligible for DXA (N) † Eligible for DXA (%) † 100% valid DXA data (N) ‡ 100% valid DXA data (%) ‡
8-11 830 830 100 739 89
12-15 630 630 100 553 88
16-19 600 600 100 514 86
20-29 954 923 97 732 79
30-39 924 901 98 676 75
40-49 875 872 100 640 73
50-59 879 879 100 667 76
Total 5692 5635 98.8 4521 80

* The number interviewed and examined is the total number of participants in the data file with a SEQN variable.
This number includes pregnant women (n=57).
†The total number eligible for DXA does not include pregnant women (n=5635).
‡ Of those eligible for DXA who successfully completed a scan.

Table 2. Percentages of participants 20 years and older with valid DXA data by body mass index (BMI) * category, NHANES 2011-12.
BMI group Interviewed and Examined (N) Eligible for DXA (N) † Eligible for DXA (%) † 100% valid DXA data (N) ‡ 100% valid DXA data (%) ‡
< 18 40 39  98  30  77 
18-24.9 1156 1139  99  873  77 
25-29.9 1124 1104  98  873  79 
30-34.9 700  693  99  521  75 
35-39.9 309  302  98  228  75 
> 40 262  258 98  181  70 
Total 3632 3575 98  2715  76 

*Measured weight in kilograms divided by measured height in meters squared.
†The total number eligible for DXA does not include pregnant women (n=5635).
‡ Of those eligible for DXA who successfully completed a scan.

Analytic Notes

The NHANES examination sample weights should be used for any analyses using the DXX_G data. 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. Both of these are available on the NHANES website.

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 8 YEARS - 59 YEARS

DXAEXSTS - Exam Status

Variable Name:
DXAEXSTS
SAS Label:
Exam Status
English Text:
Exam Status
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1 Whole body scan completed 4749 4749
2 Whole body scan completed, but invalid 3 4752
3 Whole body not scanned, pregnancy 57 4809
4 Whole body not scanned, weight > 450 lbs 1 4810
5 Whole body not scanned, height > 6'5 9 4819
6 Whole body not scanned, other reason 873 5692
. Missing 0 5692

DXAHEBV - Head Bone Invalidity Code

Variable Name:
DXAHEBV
SAS Label:
Head Bone Invalidity Code
English Text:
Head Bone Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4725 4725
1 Removable or non-removable objects 18 4743
5 Body parts out of scan region 0 4743
6 Positioning problem 5 4748
7 Other 1 4749
. Missing 943 5692

DXXHEA - Head Area (cm^2)

Variable Name:
DXXHEA
SAS Label:
Head Area (cm^2)
English Text:
Head Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
170.62 to 298.71 Range of Values 4725 4725
. Missing 967 5692

DXXHEBMC - Head Bone Mineral Content (g)

Variable Name:
DXXHEBMC
SAS Label:
Head Bone Mineral Content (g)
English Text:
Head Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
180.53 to 909.31 Range of Values 4725 4725
. Missing 967 5692

DXXHEBMD - Head Bone Mineral Density (g/cm^2)

Variable Name:
DXXHEBMD
SAS Label:
Head Bone Mineral Density (g/cm^2)
English Text:
Head Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.9 to 3.786 Range of Values 4725 4725
. Missing 967 5692

DXAHETV - Head Tissue Invalidity Code

Variable Name:
DXAHETV
SAS Label:
Head Tissue Invalidity Code
English Text:
Head Tissue Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4725 4725
1 Removable or non-removable objects 18 4743
5 Body parts out of scan region 0 4743
6 Positioning problem 5 4748
7 Other 1 4749
. Missing 943 5692

DXXHEFAT - Head Fat (g)

Variable Name:
DXXHEFAT
SAS Label:
Head Fat (g)
English Text:
Head Fat (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
615.6 to 3007 Range of Values 4725 4725
. Missing 967 5692

DXDHELE - Head Lean excl BMC (g)

Variable Name:
DXDHELE
SAS Label:
Head Lean excl BMC (g)
English Text:
Head Lean excl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1705 to 5988.6 Range of Values 4725 4725
. Missing 967 5692

DXXHELI - Head Lean incl BMC (g)

Variable Name:
DXXHELI
SAS Label:
Head Lean incl BMC (g)
English Text:
Head Lean incl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1929.6 to 6568.1 Range of Values 4725 4725
. Missing 967 5692

DXDHETOT - Head Total (g)

Variable Name:
DXDHETOT
SAS Label:
Head Total (g)
English Text:
Head Total (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2545.2 to 9575.1 Range of Values 4725 4725
. Missing 967 5692

DXDHEPF - Head Percent Fat

Variable Name:
DXDHEPF
SAS Label:
Head Percent Fat
English Text:
Head Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
22.1 to 31.4 Range of Values 4725 4725
. Missing 967 5692

DXALABV - Left Arm Bone Invalidity Code

Variable Name:
DXALABV
SAS Label:
Left Arm Bone Invalidity Code
English Text:
Left Arm Bone Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4681 4681
1 Removable or non-removable objects 28 4709
4 Arm/leg overlap 11 4720
5 Body parts out of scan region 20 4740
6 Positioning problem 7 4747
7 Other 2 4749
. Missing 943 5692

DXXLAA - Left Arm Area (cm^2)

Variable Name:
DXXLAA
SAS Label:
Left Arm Area (cm^2)
English Text:
Left Arm Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
69.89 to 386.5 Range of Values 4682 4682
. Missing 1010 5692

DXXLABMC - Left Arm BMC (g)

Variable Name:
DXXLABMC
SAS Label:
Left Arm BMC (g)
English Text:
Left Arm Body Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
33.02 to 356.56 Range of Values 4682 4682
. Missing 1010 5692

DXXLABMD - Left Arm BMD (g/cm^2)

Variable Name:
DXXLABMD
SAS Label:
Left Arm BMD (g/cm^2)
English Text:
Left Arm Body Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.353 to 1.222 Range of Values 4682 4682
. Missing 1010 5692

DXALATV - Left Arm Tissue Invalidity Code

Variable Name:
DXALATV
SAS Label:
Left Arm Tissue Invalidity Code
English Text:
Left Arm Tissue Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4670 4670
1 Removable or non-removable objects 27 4697
4 Arm/leg overlap 19 4716
5 Body parts out of scan region 24 4740
6 Positioning problem 7 4747
7 Other 2 4749
. Missing 943 5692

DXXLAFAT - Left Arm Fat (g)

Variable Name:
DXXLAFAT
SAS Label:
Left Arm Fat (g)
English Text:
Left Arm Fat (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
162.7 to 7182.4 Range of Values 4671 4671
. Missing 1021 5692

DXDLALE - Left Arm Lean excl BMC (g)

Variable Name:
DXDLALE
SAS Label:
Left Arm Lean excl BMC (g)
English Text:
Left Arm Lean excl Body Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
533.8 to 7394.7 Range of Values 4671 4671
. Missing 1021 5692

DXXLALI - Left Arm Lean incl BMC (g)

Variable Name:
DXXLALI
SAS Label:
Left Arm Lean incl BMC (g)
English Text:
Left Arm Lean incl BMC (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
579.6 to 7729.5 Range of Values 4682 4682
. Missing 1010 5692

DXDLATOT - Left Arm Total (g)

Variable Name:
DXDLATOT
SAS Label:
Left Arm Total (g)
English Text:
Left Arm Total (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
885.4 to 12749.5 Range of Values 4669 4669
. Missing 1023 5692

DXDLAPF - Left Arm Percent Fat

Variable Name:
DXDLAPF
SAS Label:
Left Arm Percent Fat
English Text:
Left Arm Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11 to 66 Range of Values 4671 4671
. Missing 1021 5692

DXALLBV - Left Leg Bone Invalidity Code

Variable Name:
DXALLBV
SAS Label:
Left Leg Bone Invalidity Code
English Text:
Left Leg Bone Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4658 4658
1 Removable or non-removable objects 50 4708
4 Arm/leg overlap 11 4719
5 Body parts out of scan region 24 4743
6 Positioning problem 5 4748
7 Other 1 4749
. Missing 943 5692

DXXLLA - Left Leg Area (cm^2)

Variable Name:
DXXLLA
SAS Label:
Left Leg Area (cm^2)
English Text:
Left Leg Area(cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
174.52 to 546.3 Range of Values 4658 4658
. Missing 1034 5692

DXXLLBMC - Left Leg BMC (g)

Variable Name:
DXXLLBMC
SAS Label:
Left Leg BMC (g)
English Text:
Left Leg Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
97.47 to 1068.96 Range of Values 4658 4658
. Missing 1034 5692

DXXLLBMD - Left Leg BMD (g/cm^2)

Variable Name:
DXXLLBMD
SAS Label:
Left Leg BMD (g/cm^2)
English Text:
Left Leg Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.516 to 2.236 Range of Values 4658 4658
. Missing 1034 5692

DXALLTV - Left Leg Tissue Invalidity Code

Variable Name:
DXALLTV
SAS Label:
Left Leg Tissue Invalidity Code
English Text:
Left Leg Tissue Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4651 4651
1 Removable or non-removable objects 50 4701
4 Arm/leg overlap 18 4719
5 Body parts out of scan region 24 4743
6 Positioning problem 5 4748
7 Other 1 4749
. Missing 943 5692

DXXLLFAT - Left Leg Fat (g)

Variable Name:
DXXLLFAT
SAS Label:
Left Leg Fat (g)
English Text:
Left Leg Fat (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
561.1 to 21616.5 Range of Values 4651 4651
. Missing 1041 5692

DXDLLLE - Left Leg Lean excl BMC (g)

Variable Name:
DXDLLLE
SAS Label:
Left Leg Lean excl BMC (g)
English Text:
Left Leg Lean excl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2005.4 to 22044 Range of Values 4651 4651
. Missing 1041 5692

DXXLLLI - Left Leg Lean incl BMC (g)

Variable Name:
DXXLLLI
SAS Label:
Left Leg Lean incl BMC (g)
English Text:
Left Leg Lean incl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2102.8 to 22806.4 Range of Values 4658 4658
. Missing 1034 5692

DXDLLTOT - Left Leg Total (g)

Variable Name:
DXDLLTOT
SAS Label:
Left Leg Total (g)
English Text:
Left Leg Total (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2798.1 to 39329.3 Range of Values 4649 4649
. Missing 1043 5692

DXDLLPF - Left Leg Percent Fat

Variable Name:
DXDLLPF
SAS Label:
Left Leg Percent Fat
English Text:
Left Leg Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11.3 to 58.8 Range of Values 4651 4651
. Missing 1041 5692

DXARABV - Right Arm Bone Invalidity Code

Variable Name:
DXARABV
SAS Label:
Right Arm Bone Invalidity Code
English Text:
Right Arm Bone Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4684 4684
1 Removable or non-removable objects 21 4705
4 Arm/leg overlap 16 4721
5 Body parts out of scan region 23 4744
6 Positioning problem 3 4747
7 Other 2 4749
. Missing 943 5692

DXXRAA - Right Arm Area (cm^2)

Variable Name:
DXXRAA
SAS Label:
Right Arm Area (cm^2)
English Text:
Right Arm Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
75.48 to 386.5 Range of Values 4684 4684
. Missing 1008 5692

DXXRABMC - Right Arm BMC (g)

Variable Name:
DXXRABMC
SAS Label:
Right Arm BMC (g)
English Text:
Right Arm Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
32.7 to 375.33 Range of Values 4684 4684
. Missing 1008 5692

DXXRABMD - Right Arm BMD (g/cm^2)

Variable Name:
DXXRABMD
SAS Label:
Right Arm BMD (g/cm^2)
English Text:
Right Arm Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.379 to 1.209 Range of Values 4684 4684
. Missing 1008 5692

DXARATV - Right Arm Tissue Invalidity Code

Variable Name:
DXARATV
SAS Label:
Right Arm Tissue Invalidity Code
English Text:
Right Arm Tissue Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4669 4669
1 Removable or non-removable objects 21 4690
4 Arm/leg overlap 28 4718
5 Body parts out of scan region 26 4744
6 Positioning problem 3 4747
7 Other 2 4749
. Missing 943 5692

DXXRAFAT - Right Arm Fat (g)

Variable Name:
DXXRAFAT
SAS Label:
Right Arm Fat (g)
English Text:
Right Arm Fat (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
171.8 to 7182.4 Range of Values 4669 4669
. Missing 1023 5692

DXDRALE - Right Arm Lean excl BMC (g)

Variable Name:
DXDRALE
SAS Label:
Right Arm Lean excl BMC (g)
English Text:
Right Arm Lean excl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
619.1 to 7438.2 Range of Values 4669 4669
. Missing 1023 5692

DXXRALI - Right Arm Lean incl BMC (g)

Variable Name:
DXXRALI
SAS Label:
Right Arm Lean incl BMC (g)
English Text:
Right Arm Lean incl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
662.7 to 7813.5 Range of Values 4684 4684
. Missing 1008 5692

DXDRATOT - Right Arm Total (g)

Variable Name:
DXDRATOT
SAS Label:
Right Arm Total (g)
English Text:
Right Arm Total (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
987.5 to 12749.5 Range of Values 4668 4668
. Missing 1024 5692

DXDRAPF - Right Arm Percent Fat

Variable Name:
DXDRAPF
SAS Label:
Right Arm Percent Fat
English Text:
Right Arm Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
10.8 to 64.1 Range of Values 4669 4669
. Missing 1023 5692

DXARLBV - Right Leg Bone Invalidity Code

Variable Name:
DXARLBV
SAS Label:
Right Leg Bone Invalidity Code
English Text:
Right Leg Bone Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4660 4660
1 Removable or non-removable objects 44 4704
4 Arm/leg overlap 18 4722
5 Body parts out of scan region 21 4743
6 Positioning problem 3 4746
7 Other 3 4749
. Missing 943 5692

DXXRLA - Right Leg Area (cm^2)

Variable Name:
DXXRLA
SAS Label:
Right Leg Area (cm^2)
English Text:
Right Leg Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
177.31 to 547.91 Range of Values 4660 4660
. Missing 1032 5692

DXXRLBMC - Right Leg BMC (g)

Variable Name:
DXXRLBMC
SAS Label:
Right Leg BMC (g)
English Text:
Right Leg Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
99.78 to 1063.78 Range of Values 4660 4660
. Missing 1032 5692

DXXRLBMD - Right Leg BMD(g/cm^2)

Variable Name:
DXXRLBMD
SAS Label:
Right Leg BMD(g/cm^2)
English Text:
Right Leg Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.533 to 2.141 Range of Values 4660 4660
. Missing 1032 5692

DXARLTV - Right Leg Tissue Invalidity Code

Variable Name:
DXARLTV
SAS Label:
Right Leg Tissue Invalidity Code
English Text:
Right Leg Tissue Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4646 4646
1 Removable or non-removable objects 45 4691
4 Arm/leg overlap 30 4721
5 Body parts out of scan region 22 4743
6 Positioning problem 3 4746
7 Other 3 4749
. Missing 943 5692

DXXRLFAT - Right Leg Fat (g)

Variable Name:
DXXRLFAT
SAS Label:
Right Leg Fat (g)
English Text:
Right Leg Fat (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
628.8 to 21616.5 Range of Values 4646 4646
. Missing 1046 5692

DXDRLLE - Right Leg Lean excl BMC (g)

Variable Name:
DXDRLLE
SAS Label:
Right Leg Lean excl BMC (g)
English Text:
Right Leg Lean excl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1942.6 to 21272.7 Range of Values 4646 4646
. Missing 1046 5692

DXXRLLI - Right Leg Lean incl BMC (g)

Variable Name:
DXXRLLI
SAS Label:
Right Leg Lean incl BMC (g)
English Text:
Right Leg Lean incl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2042.4 to 22036.5 Range of Values 4660 4660
. Missing 1032 5692

DXDRLTOT - Right Leg Total (g)

Variable Name:
DXDRLTOT
SAS Label:
Right Leg Total (g)
English Text:
Right Leg Total (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2779.5 to 39329.3 Range of Values 4646 4646
. Missing 1046 5692

DXDRLPF - Right Leg Percent Fat

Variable Name:
DXDRLPF
SAS Label:
Right Leg Percent Fat
English Text:
Right Leg Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11.6 to 59.6 Range of Values 4646 4646
. Missing 1046 5692

DXXLRA - Left Ribs Area (cm^2)

Variable Name:
DXXLRA
SAS Label:
Left Ribs Area (cm^2)
English Text:
Left Ribs Area(cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
51.27 to 199.47 Range of Values 4620 4620
. Missing 1072 5692

DXXLRBMC - Left Ribs BMC (g)

Variable Name:
DXXLRBMC
SAS Label:
Left Ribs BMC (g)
English Text:
Left Ribs Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
22.5 to 166.34 Range of Values 4620 4620
. Missing 1072 5692

DXXLRBMD - Left Ribs BMD (g/cm^2)

Variable Name:
DXXLRBMD
SAS Label:
Left Ribs BMD (g/cm^2)
English Text:
Left Ribs Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.371 to 1.067 Range of Values 4620 4620
. Missing 1072 5692

DXXRRA - Right Ribs Area (cm^2)

Variable Name:
DXXRRA
SAS Label:
Right Ribs Area (cm^2)
English Text:
Right Ribs Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
50.06 to 233.57 Range of Values 4620 4620
. Missing 1072 5692

DXXRRBMC - Right Ribs BMC (g)

Variable Name:
DXXRRBMC
SAS Label:
Right Ribs BMC (g)
English Text:
Right Ribs Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
18.32 to 211.89 Range of Values 4620 4620
. Missing 1072 5692

DXXRRBMD - Right Ribs BMD (g/cm^2)

Variable Name:
DXXRRBMD
SAS Label:
Right Ribs BMD (g/cm^2)
English Text:
Right Ribs Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.352 to 1.035 Range of Values 4620 4620
. Missing 1072 5692

DXXTSA - Thoracic Spine Area (cm^2)

Variable Name:
DXXTSA
SAS Label:
Thoracic Spine Area (cm^2)
English Text:
Thoracic Spine Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
44.46 to 231.54 Range of Values 4620 4620
. Missing 1072 5692

DXXTSBMC - Thoracic Spine BMC (g)

Variable Name:
DXXTSBMC
SAS Label:
Thoracic Spine BMC (g)
English Text:
Thoracic Spine Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
18.9 to 284.97 Range of Values 4620 4620
. Missing 1072 5692

DXXTSBMD - Thoracic Spine BMD (g/cm^2)

Variable Name:
DXXTSBMD
SAS Label:
Thoracic Spine BMD (g/cm^2)
English Text:
Thoracic Spine Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.383 to 1.491 Range of Values 4620 4620
. Missing 1072 5692

DXXLSA - Lumbar Spine Area (cm^2)

Variable Name:
DXXLSA
SAS Label:
Lumbar Spine Area (cm^2)
English Text:
Lumbar Spine Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
10.81 to 109.7 Range of Values 4620 4620
. Missing 1072 5692

DXXLSBMC - Lumbar Spine BMC (g)

Variable Name:
DXXLSBMC
SAS Label:
Lumbar Spine BMC (g)
English Text:
Lumbar Spine Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6.21 to 156.14 Range of Values 4620 4620
. Missing 1072 5692

DXXLSBMD - Lumbar Spine BMD (g/cm^2)

Variable Name:
DXXLSBMD
SAS Label:
Lumbar Spine BMD (g/cm^2)
English Text:
Lumbar Spine Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.518 to 2.477 Range of Values 4620 4620
. Missing 1072 5692

DXXPEA - Pelvis Area (cm^2)

Variable Name:
DXXPEA
SAS Label:
Pelvis Area (cm^2)
English Text:
Pelvis Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
70.68 to 372.99 Range of Values 4620 4620
. Missing 1072 5692

DXXPEBMC - Pelvis BMC (g)

Variable Name:
DXXPEBMC
SAS Label:
Pelvis BMC (g)
English Text:
Pelvis Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
50.94 to 838.59 Range of Values 4620 4620
. Missing 1072 5692

DXXPEBMD - Pelvis BMD (g/cm^2)

Variable Name:
DXXPEBMD
SAS Label:
Pelvis BMD (g/cm^2)
English Text:
Pelvis Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.542 to 2.767 Range of Values 4620 4620
. Missing 1072 5692

DXATRBV - Trunk Bone Invalidity Code

Variable Name:
DXATRBV
SAS Label:
Trunk Bone Invalidity Code
English Text:
Trunk Bone Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4620 4620
1 Removable or non-removable objects 118 4738
3 Excessive x-ray noise due to morbid obesity 7 4745
4 Arm/leg overlap 0 4745
5 Body parts out of scan region 1 4746
6 Positioning problem 2 4748
7 Other 1 4749
. Missing 943 5692

DXDTRA - Trunk Bone area (cm^2)

Variable Name:
DXDTRA
SAS Label:
Trunk Bone area (cm^2)
English Text:
Trunk Bone area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
289.53 to 929.68 Range of Values 4620 4620
. Missing 1072 5692

DXDTRBMC - Trunk BMC (g)

Variable Name:
DXDTRBMC
SAS Label:
Trunk BMC (g)
English Text:
Trunk Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
141.45 to 1503.65 Range of Values 4620 4620
. Missing 1072 5692

DXDTRBMD - Trunk Bone BMD (g/cm^2)

Variable Name:
DXDTRBMD
SAS Label:
Trunk Bone BMD (g/cm^2)
English Text:
Trunk Bone BMD (g/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.46 to 1.796 Range of Values 4620 4620
. Missing 1072 5692

DXATRTV - Trunk Tissue Invalidity Code

Variable Name:
DXATRTV
SAS Label:
Trunk Tissue Invalidity Code
English Text:
Trunk Tissue Invalidity Code
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0 Valid data 4621 4621
1 Removable or non-removable objects 116 4737
3 Excessive x-ray noise due to morbid obesity 7 4744
4 Arm/leg overlap 0 4744
5 Body parts out of scan region 1 4745
6 Positioning problem 2 4747
7 Other 2 4749
. Missing 943 5692

DXXTRFAT - Trunk Fat (g)

Variable Name:
DXXTRFAT
SAS Label:
Trunk Fat (g)
English Text:
Trunk Fat (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1042.7 to 51926.4 Range of Values 4621 4621
. Missing 1071 5692

DXDTRLE - Trunk Lean excl BMC (g)

Variable Name:
DXDTRLE
SAS Label:
Trunk Lean excl BMC (g)
English Text:
Trunk Lean excl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
5926.2 to 55580.7 Range of Values 4621 4621
. Missing 1071 5692

DXXTRLI - Trunk Lean incl BMC (g)

Variable Name:
DXXTRLI
SAS Label:
Trunk Lean incl BMC (g)
English Text:
Trunk Lean incl Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
6067.6 to 56558.4 Range of Values 4620 4620
. Missing 1072 5692

DXDTRTOT - Trunk Total (g)

Variable Name:
DXDTRTOT
SAS Label:
Trunk Total (g)
English Text:
Trunk Total (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
7353.9 to 100735.5 Range of Values 4618 4618
. Missing 1074 5692

DXDTRPF - Trunk Percent Fat

Variable Name:
DXDTRPF
SAS Label:
Trunk Percent Fat
English Text:
Trunk Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
10.4 to 58 Range of Values 4621 4621
. Missing 1071 5692

DXDSTA - Subtotal Area (cm^2)

Variable Name:
DXDSTA
SAS Label:
Subtotal Area (cm^2)
English Text:
Subtotal Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
841.03 to 2604.47 Range of Values 4445 4445
. Missing 1247 5692

DXDSTBMC - Subtotal BMC (g)

Variable Name:
DXDSTBMC
SAS Label:
Subtotal BMC (g)
English Text:
Subtotal Bone Mineral Content (grams)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
410.14 to 4325.99 Range of Values 4445 4445
. Missing 1247 5692

DXDSTBMD - Subtotal BMD (g/cm^2)

Variable Name:
DXDSTBMD
SAS Label:
Subtotal BMD (g/cm^2)
English Text:
Subtotal Bone Mineral Density (grams/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.467 to 1.813 Range of Values 4445 4445
. Missing 1247 5692

DXDSTFAT - Subtotal Fat (g)

Variable Name:
DXDSTFAT
SAS Label:
Subtotal Fat (g)
English Text:
Subtotal Fat (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
2587.6 to 100159.8 Range of Values 4544 4544
. Missing 1148 5692

DXDSTLE - Subtotal Lean excl BMC (g)

Variable Name:
DXDSTLE
SAS Label:
Subtotal Lean excl BMC (g)
English Text:
Subtotal Lean excl BMC (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11247.1 to 107447.8 Range of Values 4544 4544
. Missing 1148 5692

DXDSTLI - Subtotal Lean incl BMC (g)

Variable Name:
DXDSTLI
SAS Label:
Subtotal Lean incl BMC (g)
English Text:
Subtotal Lean incl BMC (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11657.3 to 110602.9 Range of Values 4441 4441
. Missing 1251 5692

DXDSTTOT - Subtotal (Total excl Head) (g)

Variable Name:
DXDSTTOT
SAS Label:
Subtotal (Total excl Head) (g)
English Text:
Subtotal (Total excl Head) (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
14804.3 to 177770 Range of Values 4544 4544
. Missing 1148 5692

DXDSTPF - Subtotal Percent Fat

Variable Name:
DXDSTPF
SAS Label:
Subtotal Percent Fat
English Text:
Subtotal Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
11 to 56.3 Range of Values 4544 4544
. Missing 1148 5692

DXDTOA - Total Area (cm^2)

Variable Name:
DXDTOA
SAS Label:
Total Area (cm^2)
English Text:
Total Area (cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
1054.56 to 2851.27 Range of Values 4524 4524
. Missing 1168 5692

DXDTOBMC - Total Bone Mineral Content (g)

Variable Name:
DXDTOBMC
SAS Label:
Total Bone Mineral Content (g)
English Text:
Total Bone Mineral Content (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
634.7 to 4900.82 Range of Values 4524 4524
. Missing 1168 5692

DXDTOBMD - Total Bone Mineral Density (g/cm^2)

Variable Name:
DXDTOBMD
SAS Label:
Total Bone Mineral Density (g/cm^2)
English Text:
Total Bone Mineral Density (g/cm^2)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
0.598 to 1.88 Range of Values 4524 4524
. Missing 1168 5692

DXDTOFAT - Total Fat (g)

Variable Name:
DXDTOFAT
SAS Label:
Total Fat (g)
English Text:
Total Fat (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
3410.9 to 102288.7 Range of Values 4521 4521
. Missing 1171 5692

DXDTOLE - Total Lean excl BMC (g)

Variable Name:
DXDTOLE
SAS Label:
Total Lean excl BMC (g)
English Text:
Total Lean excl BMC (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
12952.1 to 112233.1 Range of Values 4544 4544
. Missing 1148 5692

DXDTOLI - Total Lean incl BMC (g)

Variable Name:
DXDTOLI
SAS Label:
Total Lean incl BMC (g)
English Text:
Total Lean incl BMC (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
13586.8 to 115895.4 Range of Values 4521 4521
. Missing 1171 5692

DXDTOTOT - Total Lean+Fat (g)

Variable Name:
DXDTOTOT
SAS Label:
Total Lean+Fat (g)
English Text:
Total Lean+Fat (g)
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
17349.5 to 184743.3 Range of Values 4521 4521
. Missing 1171 5692

DXDTOPF - Total Percent Fat

Variable Name:
DXDTOPF
SAS Label:
Total Percent Fat
English Text:
Total Percent Fat
Target:
Both males and females 8 YEARS - 59 YEARS
Code or Value Value Description Count Cumulative Skip to Item
12.1 to 55.4 Range of Values 4521 4521
. Missing 1171 5692