Table of Contents

Component Description

Users of the 2017-2018 dual-energy X-ray absorptiometry whole body data (DXX_J) 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 2011-2018. 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

Participants aged 8-59 years were eligible. Pregnant females were excluded from the DXA examination. Participants who were excluded from the DXA examination for reasons other than pregnancy were 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 the 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_I 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 Shepherd Research Lab at the University of California, San Francisco (UCSF), Department of Radiology (2017) and at the University of Hawaii (UH) Cancer Center (2018), during review of participant scans. The codes documented when the technologist 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 Shepherd Research Lab when problems were noted during review of the scans. Constant communication was maintained throughout the year among the Shepherd Research Lab, 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 quality control center when the scanners were serviced or repaired so any changes in measurement, as a result of the work, was assessed.

Scan Analysis
Each participant scan and phantom scan was reviewed and analyzed by the Shepherd Research Lab 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 2017-18. Expert review was conducted by the Shepherd Research Lab on 100% of analyzed participant scans to verify the accuracy and consistency of the results.

Invalidity Codes
Invalidity codes were applied by the Shepherd Research Lab 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 may 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 2017-2018, longitudinal monitoring was conducted through daily spine phantom scans as required by the manufacturer, whole body slim-line phantom scans and air scans in order to correct any scanner-related changes in participant data were conducted 3 times per week. 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 Shepherd Research Lab 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 Shepherd Research Lab.

After applying the correction factors developed by Shepherd Research Lab 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 2017-2018 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 2017-18.
Age group (years) Interviewed and Examined (N)* Eligible for DXA (N) † Eligible for DXA (%) † 100% valid DXA data (N) ‡ 100% valid DXA data (%) ‡
8-11 731 731  100  574  79 
12-15 573  573  100  413  72 
16-19 563  563  100  421  75 
20-29 776  750  97  547  73 
30-39 813  788  97  543  69 
40-49 778  774  99  553  71 
50-59 880  880  100  606  69 
Total 5114  5059  99  3657  72 

* The number interviewed and examined is the total number of participants in the data file with a SEQN variable. This number includes pregnant women.
†The total number eligible for DXA does not include pregnant women.
‡ 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 2017-18.
BMI group Interviewed and Examined (N) Eligible for DXA (N) † Eligible for DXA (%) † 100% valid DXA data (N) ‡ 100% valid DXA data (%) ‡
< 18 42  42  100  26  62 
18-24.9 839  830  99  644  78 
25-29.9 959  942  98  699  74 
30-34.9 675  663  98  472  71 
35-39.9 353  343  97  231  67 
> 40 344  337  98  167  50 
Total 3247  3192  98  2249  70 

*Measured weight in kilograms divided by measured height in meters squared.
†The total number eligible for DXA does not include pregnant women.
‡ 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 4336 4336
2 Whole body scan completed, but invalid 21 4357
3 Whole body not scanned, pregnancy 63 4420
4 Whole body not scanned, weight > 450 lbs 2 4422
5 Whole body not scanned, height > 6'5 2 4424
6 Whole body not scanned, other reason 690 5114
. Missing 0 5114

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 4137 4137
1 Removable or non-removable objects 157 4294
5 Body parts out of scan region 32 4326
6 Positioning problem 9 4335
7 Other 1 4336
. Missing 778 5114

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
163.6 to 336.95 Range of Values 4072 4072
. Missing 1042 5114

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
185.82 to 1144.25 Range of Values 4072 4072
. Missing 1042 5114

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
1.032 to 4.182 Range of Values 4072 4072
. Missing 1042 5114

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 4137 4137
1 Removable or non-removable objects 157 4294
5 Body parts out of scan region 32 4326
6 Positioning problem 9 4335
7 Other 1 4336
. Missing 778 5114

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
678.6 to 1879.7 Range of Values 4072 4072
. Missing 1042 5114

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
1881.8 to 4955.2 Range of Values 4072 4072
. Missing 1042 5114

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
2155.3 to 5690.2 Range of Values 4072 4072
. Missing 1042 5114

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
2833.9 to 7548.7 Range of Values 4072 4072
. Missing 1042 5114

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
21.7 to 27.5 Range of Values 4072 4072
. Missing 1042 5114

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 4161 4161
1 Removable or non-removable objects 38 4199
4 Arm/leg overlap 59 4258
5 Body parts out of scan region 59 4317
6 Positioning problem 17 4334
7 Other 2 4336
. Missing 778 5114

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
71.22 to 392.54 Range of Values 4095 4095
. Missing 1019 5114

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
33.34 to 435.14 Range of Values 4095 4095
. Missing 1019 5114

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
0.367 to 1.342 Range of Values 4095 4095
. Missing 1019 5114

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 4146 4146
1 Removable or non-removable objects 39 4185
4 Arm/leg overlap 71 4256
5 Body parts out of scan region 61 4317
6 Positioning problem 17 4334
7 Other 2 4336
. Missing 778 5114

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
181.5 to 6857.8 Range of Values 4081 4081
. Missing 1033 5114

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
676.8 to 8370.4 Range of Values 4081 4081
. Missing 1033 5114

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
723.8 to 8671.4 Range of Values 4095 4095
. Missing 1019 5114

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
979.5 to 12317.3 Range of Values 4055 4055
. Missing 1059 5114

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
10.5 to 69.2 Range of Values 4081 4081
. Missing 1033 5114

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 4078 4078
1 Removable or non-removable objects 45 4123
4 Arm/leg overlap 50 4173
5 Body parts out of scan region 147 4320
6 Positioning problem 14 4334
7 Other 2 4336
. Missing 778 5114

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
68.42 to 538.72 Range of Values 4019 4019
. Missing 1095 5114

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
57.25 to 986.06 Range of Values 4019 4019
. Missing 1095 5114

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
0.557 to 1.993 Range of Values 4019 4019
. Missing 1095 5114

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 4062 4062
1 Removable or non-removable objects 44 4106
4 Arm/leg overlap 64 4170
5 Body parts out of scan region 150 4320
6 Positioning problem 14 4334
7 Other 2 4336
. Missing 778 5114

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
604.4 to 20292.1 Range of Values 4004 4004
. Missing 1110 5114

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
2036.7 to 23667.6 Range of Values 4004 4004
. Missing 1110 5114

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
2165.6 to 24345.1 Range of Values 4019 4019
. Missing 1095 5114

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
3261.8 to 40056.9 Range of Values 3981 3981
. Missing 1133 5114

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
10.7 to 61.1 Range of Values 4004 4004
. Missing 1110 5114

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 4094 4094
1 Removable or non-removable objects 39 4133
4 Arm/leg overlap 77 4210
5 Body parts out of scan region 108 4318
6 Positioning problem 16 4334
7 Other 2 4336
. Missing 778 5114

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
79.95 to 392.54 Range of Values 4031 4031
. Missing 1083 5114

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
34.16 to 455.69 Range of Values 4031 4031
. Missing 1083 5114

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
0.386 to 1.494 Range of Values 4031 4031
. Missing 1083 5114

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 4071 4071
1 Removable or non-removable objects 36 4107
4 Arm/leg overlap 99 4206
5 Body parts out of scan region 112 4318
6 Positioning problem 16 4334
7 Other 2 4336
. Missing 778 5114

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
162.2 to 6857.8 Range of Values 4008 4008
. Missing 1106 5114

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
720.1 to 7968.7 Range of Values 4008 4008
. Missing 1106 5114

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
767.5 to 8388.9 Range of Values 4031 4031
. Missing 1083 5114

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
1035.6 to 10706.8 Range of Values 3981 3981
. Missing 1133 5114

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
11.1 to 66.8 Range of Values 4008 4008
. Missing 1106 5114

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 4049 4049
1 Removable or non-removable objects 58 4107
4 Arm/leg overlap 77 4184
5 Body parts out of scan region 144 4328
6 Positioning problem 7 4335
7 Other 1 4336
. Missing 778 5114

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
61.62 to 526.94 Range of Values 3988 3988
. Missing 1126 5114

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
46.03 to 1136.3 Range of Values 3988 3988
. Missing 1126 5114

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
0.592 to 2.613 Range of Values 3988 3988
. Missing 1126 5114

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 4027 4027
1 Removable or non-removable objects 56 4083
4 Arm/leg overlap 100 4183
5 Body parts out of scan region 145 4328
6 Positioning problem 7 4335
7 Other 1 4336
. Missing 778 5114

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
660.5 to 21280.6 Range of Values 3966 3966
. Missing 1148 5114

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
2012.6 to 23667.6 Range of Values 3966 3966
. Missing 1148 5114

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
2128.8 to 24345.1 Range of Values 3988 3988
. Missing 1126 5114

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
3358.7 to 40056.9 Range of Values 3942 3942
. Missing 1172 5114

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
10.9 to 63.8 Range of Values 3966 3966
. Missing 1148 5114

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
55.96 to 233.02 Range of Values 3912 3912
. Missing 1202 5114

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
24.61 to 162.57 Range of Values 3912 3912
. Missing 1202 5114

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
0.359 to 1.134 Range of Values 3912 3912
. Missing 1202 5114

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
52.42 to 259.82 Range of Values 3912 3912
. Missing 1202 5114

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
22.22 to 217.71 Range of Values 3912 3912
. Missing 1202 5114

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
0.353 to 1.227 Range of Values 3912 3912
. Missing 1202 5114

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
51.97 to 247.44 Range of Values 3912 3912
. Missing 1202 5114

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
23.28 to 268.31 Range of Values 3912 3912
. Missing 1202 5114

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
0.369 to 1.336 Range of Values 3912 3912
. Missing 1202 5114

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
9.99 to 85.14 Range of Values 3912 3912
. Missing 1202 5114

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
5.86 to 151.26 Range of Values 3912 3912
. Missing 1202 5114

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
0.492 to 1.777 Range of Values 3912 3912
. Missing 1202 5114

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
67.56 to 357.37 Range of Values 3912 3912
. Missing 1202 5114

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
54.57 to 695.13 Range of Values 3912 3912
. Missing 1202 5114

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
0.554 to 2.277 Range of Values 3912 3912
. Missing 1202 5114

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 3973 3973
1 Removable or non-removable objects 138 4111
3 Excessive x-ray noise due to morbid obesity 210 4321
4 Arm/leg overlap 4 4325
5 Body parts out of scan region 4 4329
6 Positioning problem 6 4335
7 Other 1 4336
. Missing 778 5114

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
293.81 to 1027.33 Range of Values 3918 3918
. Missing 1196 5114

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
152.18 to 1257.96 Range of Values 3912 3912
. Missing 1202 5114

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
0.446 to 1.557 Range of Values 3918 3918
. Missing 1196 5114

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 3973 3973
1 Removable or non-removable objects 135 4108
3 Excessive x-ray noise due to morbid obesity 211 4319
4 Arm/leg overlap 5 4324
5 Body parts out of scan region 6 4330
6 Positioning problem 5 4335
7 Other 1 4336
. Missing 778 5114

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
1093.3 to 46570.5 Range of Values 3912 3912
. Missing 1202 5114

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
5923.2 to 56097.6 Range of Values 3912 3912
. Missing 1202 5114

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
6087.6 to 57055.5 Range of Values 3912 3912
. Missing 1202 5114

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
7291.2 to 95313.2 Range of Values 3903 3903
. Missing 1211 5114

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
10.1 to 56.4 Range of Values 3912 3912
. Missing 1202 5114

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
873.43 to 2609.89 Range of Values 3569 3569
. Missing 1545 5114

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
433.64 to 3870.67 Range of Values 3569 3569
. Missing 1545 5114

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
0.496 to 1.616 Range of Values 3569 3569
. Missing 1545 5114

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
2752.8 to 85821.8 Range of Values 3820 3820
. Missing 1294 5114

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
11772 to 100847.6 Range of Values 3820 3820
. Missing 1294 5114

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
12302.9 to 100827.1 Range of Values 3563 3563
. Missing 1551 5114

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
16011.8 to 173915.6 Range of Values 3820 3820
. Missing 1294 5114

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
10.8 to 57.3 Range of Values 3820 3820
. Missing 1294 5114

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
1071.34 to 2842.93 Range of Values 3669 3669
. Missing 1445 5114

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
650.36 to 4585.87 Range of Values 3669 3669
. Missing 1445 5114

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
0.592 to 1.728 Range of Values 3669 3669
. Missing 1445 5114

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
3560 to 86890.2 Range of Values 3658 3658
. Missing 1456 5114

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
13745.8 to 105578.4 Range of Values 3820 3820
. Missing 1294 5114

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
14542.9 to 108410.7 Range of Values 3658 3658
. Missing 1456 5114

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
18963.1 to 180889.1 Range of Values 3658 3658
. Missing 1456 5114

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 56.1 Range of Values 3658 3658
. Missing 1456 5114