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Whole Body Dual X-Ray Absorptiometry (DEXA) to Determine Body Composition

Policy Number: MP-194

Latest Review Date: October 2023

Category:  Radiology                                                             


Dual x-ray absorptiometry (DXA) body composition studies is considered investigational.


Using low dose x-rays of two different energy levels, whole body dual x-ray absorptiometry (DXA) measures lean tissue mass and total and regional body fat as well as bone density. DXA scans have become a tool for research on body composition e.g. as a more convenient replacement for underwater weighing. This review addresses potential applications in clinical care rather than research use of the technology.

Body Composition Measurement

Body composition measurements can be used to quantify and assess the relative proportions of specific body compartments such as fat and lean mass (e.g., bones, tissues, organs, muscles). These measurements may be more useful in informing diagnosis, prognosis, or therapy than standard assessments (e.g., body weight, body mass index) that do not identify the contributions of individual body compartments or their particular relationships with health and disease. While these body composition measurements have been most frequently utilized for research purposes, they may be useful in clinical settings to:

  • Evaluate the health status of undernourished patients, those impacted by certain disease states (e.g., anorexia nervosa, cachexia), or those undergoing certain treatments (eg, antiretroviral therapy, bariatric surgery).
  • Evaluate the risk of heart disease or diabetes by measuring visceral fat vs total body fat.
  • Assess body composition changes related to growth and development (e.g., infancy, childhood), aging (e.g., sarcopenia), and in certain disease states (eg, HIV, diabetes).
  • Evaluate patients in situations where body mass index is suspected to be discordant with total fat mass (e.g., body-building, edema).

A variety of techniques have been researched, including most commonly, anthropomorphic measures, bioelectrical impedance, and dual X-ray absorptiometry (DXA).  All of these techniques are based in part on assumptions regarding the distribution of different body compartments and their density, and all rely on formulas to convert the measured parameter into an estimate of body composition. Therefore, all techniques will introduce variation based how the underlying assumptions and formulas apply to different populations of subjects, (i.e., different age groups, ethnicities, or underlying conditions). Techniques using anthropomorphics, bioelectrical impedance, underwater weighing, and DXA are briefly reviewed as followed.

Anthropomorphic Techniques

Anthropomorphic techniques for the estimation of body composition include measurements of skinfold thickness at various sites, bone dimensions, and limb circumference. These measurements are used in various equations to predict body density and body fat. Due to its ease of use, measurement of skinfold thickness is 1 of the most common techniques. The technique is based on the assumption that the subcutaneous adipose layer reflects total body fat but this association may vary with age and sex. Skinfold thickness measurement precision and utility can also be affected by operator experience and a lack of applicable reference data for specific patient populations or percentile extremes.

Bioelectrical Impedance

Bioelectrical impedance is based on the relationship between the volume of the conductor (i.e., the human body), the conductor’s length (i.e., height), the components of the conductor (i.e., fat and fat-free mass), and its impedance. The technique involves attaching surface electrodes to various locations on the arm and foot. Alternatively, the patient can stand on pad electrodes. Estimates of body composition are based on the assumption that the overall conductivity of the human body is closely related to lean tissue. The impedance value is then combined with anthropomorphic data and certain other patient-specific parameters (eg, age, gender, ethnicity) to give body compartment measures. These measures are calculated based on device manufacturer-specific regression models, which are generally proprietary. Bioelectrical impedance measures can be affected by fat distribution patterns, hydration status, ovulation, and temperature.

Underwater Weighing

Underwater weighing requires the use of a specially constructed tank in which the subject is seated on a suspended chair. The subject is then submerged in the water while exhaling; the difference between weight in air and weight in water is used to estimate total body fat percentage. While valued as a research tool, weighing people underwater is obviously not suitable for routine clinical use. This technique is based on the assumption that the body can be divided into two compartments with constant densities: adipose tissue with a density of 0.9gm/cm3 and lean body mass (i.e., muscle and bone) with a density of 1.1 g/cm3. One limitation of the underlying assumption is the variability in density between muscle and bone; for example, bone has a higher density than muscle, and bone mineral density varies with age and other conditions. Also, the density of body fat may vary, depending on the relative components of its constituents, (e.g., glycerides, sterols, and glycolipids).

Dual X-Ray Absorptiometry (DXA)

While the cited techniques assume 2 body compartments, DXA can estimate three body compartments consisting of fat mass, lean body mass, and bone mass. DXA systems use a source that generates x-rays at two energies. The differential attenuation of the two energies is used to estimate the bone mineral content and the soft tissue composition. When two x-ray energies are used, only two tissue compartments can be measured; therefore, soft tissue measurements (i.e., fat and lean body mass) can only be measured in areas in which no bone is present. DXA also has the ability to determine body composition in defined regions, i.e., in the arms, legs, and trunk. DXA measurements are based in part on the assumption that the hydration of fat-free mass remains constant at 73%. Hydration, however, can vary from 67% to 85% and can be variable in certain disease states. Other assumptions used to derive body composition estimates are considered proprietary by DXA manufacturers.


The most recent literature review was updated through July 18, 2023.

Summary of Evidence

For individuals who have a clinical condition associated with abnormal body composition who receive dual-energy x-ray absorptiometry (DXA) body composition studies, the evidence includes systematic reviews and several cross-sectional studies comparing DXA with other techniques. Relevant outcomes are symptoms and change in disease status. The available studies are primarily conducted in research settings and often use DXA body composition studies as a reference standard. Systematic reviews with meta-analyses exploring the clinical validity of DXA measurements against reference methods for the quantification of fat mass indicate strong overall agreement between these modalities, but raise concerns regarding precision and reliability in some populations, particularly those without existing clinical conditions for which risk of adverse outcomes is influenced by abnormal visceral adiposity. More importantly, no studies were identified in which DXA body composition measurements were actively used in patient management. The evidence is insufficient to determine that the technology results in an improvement in the net health outcome.

For individuals who have a clinical condition managed by monitoring changes in body composition over time who receive serial DXA body composition studies, the evidence includes several prospective studies monitoring patients over time. Relevant outcomes are symptoms and change in disease status. The studies used DXA as a tool to measure body composition and were not designed to assess the accuracy of DXA. None of the studies used DXA findings to make patient management decisions or addressed how serial body composition assessment might improve health outcomes. The evidence is insufficient to determine the effects of the technology on health outcomes.

Practice Guidelines and Position Statements

American College of Radiology et al

The American College of Radiology (ACR), the Society for Pediatric Radiology (SPR), and the Society of Skeletal Radiology (SRR) (2018) issued a collaborative practice parameter to assist practitioners in providing appropriate radiologic care for their patients. DXA was described as a "clinically proven, accurate and reproducible method of measuring bone mineral density (BMD) in the lumbar spine, proximal femur, forearm, and whole body," that "may also be used to measure whole-body composition, including nonbone lean mass (LM) and fat mass (FM)." DXA measurement of BMD, LM, or FM is indicated whenever a clinical decision is likely to be directly influenced by the test result. In particular, LM and FM may be useful in assessing conditions such as sarcopenia and cachexia. Specifically, DXA may be indicated as a tool for the measurement of regional and whole body FM and LM in patients afflicted with conditions such as malabsorption, cancer, or eating disorders.

The International Society for Clinical Densitometry

The International Society for Clinical Densitometry (2015) updated its statements on the use of dual x-ray absorptiometry (DXA) for body composition. The following statements were made on the use of DXA total body composition with regional analysis:

  • To assess fat distribution in patients with HIV who are using antiretroviral agents known to increase the risk of lipoatrophy.
  • To assess fat and lean mass changes in obese patients undergoing bariatric surgery (or medical, diet, or weight loss regimens with anticipated large weight loss) when weight loss exceeds approximately 10%. The statement noted that the impact of DXA studies on clinical outcomes in these patients is uncertain.
  • To assess fat and lean mass in patients with muscle weakness and poor physical functioning. The impact on clinical outcomes is uncertain.

Of note, pregnancy is a contraindication to use of DXA to measure body composition. The statement also adds that the clinical utility of DXA measurements of adiposity and lean mass (e.g., visceral adipose tissue, lean mass index, fat mass index) is uncertain. Furthermore, while the use of DXA adiposity measures such as fat mass index may be useful in risk-stratifying patients for cardio-metabolic outcomes, specific thresholds to define obesity have not been established.

International Conference on Sarcopenia and Frailty Research Task Force

Evidence-based clinical practice guidelines for the screening, diagnosis, and management of sarcopenia were developed by the International Conference on Sarcopenia and Frailty Research (ICSFR) task force in 2018. The following recommendations were made:

  • Screening for sarcopenia can be performed using gait speed analysis or SARC-F questionnaire.
  • Individuals screened as positive for sarcopenia should be referred for further assessment to confirm the presence of the
  • disease.
  • DXA imaging should be used to determine low levels of lean body mass when diagnosing sarcopenia.

The recommendation regarding the diagnostic use of DXA received a conditional (weak) recommendation. The certainty of the evidence for DXA assessment was ranked low due to:

  • DXA studies featuring populations from low-middle income countries are lacking.
  • DXA measurement of lean body mass rather than muscle mass may potentially misclassify body composition in certain individuals.
  • Incorporation of DXA measurements of lean body mass may have limited additional benefit for the prediction of relevant health outcomes (eg, falls,
  • fractures, lowered physical performance, mobility).

U.S. Preventive Services Task Force Recommendations

No U.S. Preventive Services Task Force recommendations for whole body DXA have been identified.


Dual X-ray absorptiometry (DXA), body composition assessment, anthropomorphic techniques, skin-fold thickness, body composition, DXA, Total Body DXA scan


Body composition software for several bone densitometer systems have been approved by the U.S. Food and Drug Administration through premarket approval process. This includes Lunar iDXA systems (GE Healthcare, Madison, WI), Hologic DXA systems (Hologic, Bedford MA), and Norland DXA systems (Norland Corp., Fort Atkinson, WI).


Coverage is subject to member’s specific benefits.  Group-specific policy will supersede this policy when applicable.

ITS: Home Policy provisions apply

FEP contracts: Special benefit consideration may apply. Refer to member’s benefit plan.  


CPT codes: 


Unlisted diagnostic radiographic procedure


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  11. Calella P, Valerio G, Brodlie M et al. Cystic fibrosis, body composition, and health outcomes: a systematic review. Nutrition, 2018 Nov;55-56:131-139.
  12. Calella P, Valerio G, Brodlie M et al. Tools and Methods Used for the Assessment of Body Composition in Patients With Cystic Fibrosis: A Systematic Review. Nutr Clin Pract, 2019 Feb 7.
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  23. Kullberg J, Brandberg J, Angelhed JE et al. Whole-body adipose tissue analysis: comparison of MRI, CT and dual energy x-ray absorptiometry. Br J Radiol 2009; 82(974):123-130.
  24. Liem ET, De Lucia Rolfe E, L’Abee C et al. Measuring abdominal adiposity in 6 to 7 year old children. Eur J Clin Nutr 2009; 63(7):835-841.
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  37. Ziai S, Coriati A, Chabot K, et al. Agreement of bioelectric impedance analysis and dual-energy X-ray absorptiometry for body composition evaluation in adults with cystic fibrosis. J Cyst Fibros. Sep 2014; 13(5):585-588.


Medical Policy Group, August 2004 (4)

Medical Policy Administration Committee, August 2004

Available for comment August 24-October 7, 2004

Medical Policy Group, August 2006 (1)

Medical Policy Group, January 2007 (2)

Medical Policy Group, January 2009 (1)

Medical Policy Panel, February 2010

Medical Policy Group, June 2010 (2)

Medical Policy Group, June 2011; Added Key Word

Medical Policy Group, July 2011; Updated Key Points and References

Medical Policy Group, February 2012 (2): 2012 Update-Key Points & References

Medical Policy Group, January 2013 (2): 2013 Update to Key Points & References; policy statement remains unchanged

Medical Policy Panel, December 2014

Medical Policy Group, December 2014 (4): Update to Key Points, Approved Governing Bodies, and References. No change in policy statement.

Medical Policy Panel, December 2015

Medical Policy Group, December 2015 (2): 2015 Updates to Description, Key Points, and References; no change in policy statement.

Medical Policy Panel, September 2017

Medical Policy Group, September 2017 (7):  Updates to Description, Key Points, and References. Removed Previous Coding section (0028T deleted effective Jan 2009). No change in policy statement.

Medical Policy Panel, September 2018

Medical Policy Group, October 2018 (7):  Updates to Key Points and References. No change in policy statement.

Medical Policy Panel, September 2019

Medical Policy Group, September 2019 (7):  Updates to Key Points and References. No change in policy statement.

Medical Policy Panel, September 2020

Medical Policy Group, September 2020 (7):  Updates to Description, Key Points and References. No change in policy statement.

Medical Policy Panel, September 2021

Medical Policy Group, September 2021 (7): Literature review completed. Minor updates to Key Points. No new references added. Removed “not medically necessary” statement from Policy Statement. No change in intent.

Medical Policy Panel, September 2022

Medical Policy Group, September 2022 (7): Updates to Key Points and References. No change in policy statement.

Medical Policy Panel, September 2023

Medical Policy Group, October 2023 (7): Updates to Description, Key Points, Benefit Application, and References. No change to Policy Statement.


This medical policy is not an authorization, certification, explanation of benefits, or a contract. Eligibility and benefits are determined on a case-by-case basis according to the terms of the member’s plan in effect as of the date services are rendered. All medical policies are based on (i) research of current medical literature and (ii) review of common medical practices in the treatment and diagnosis of disease as of the date hereof. Physicians and other providers are solely responsible for all aspects of medical care and treatment, including the type, quality, and levels of care and treatment.


This policy is intended to be used for adjudication of claims (including pre-admission certification, pre-determinations, and pre-procedure review) in Blue Cross and Blue Shield’s administration of plan contracts.

The plan does not approve or deny procedures, services, testing, or equipment for our members. Our decisions concern coverage only. The decision of whether or not to have a certain test, treatment or procedure is one made between the physician and his/her patient. The plan administers benefits based on the member’s contract and corporate medical policies. Physicians should always exercise their best medical judgment in providing the care they feel is most appropriate for their patients. Needed care should not be delayed or refused because of a coverage determination.


As a general rule, benefits are payable under health plans only in cases of medical necessity and only if services or supplies are not investigational, provided the customer group contracts have such coverage.

The following Association Technology Evaluation Criteria must be met for a service/supply to be considered for coverage:

  1. The technology must have final approval from the appropriate government regulatory bodies;
  2. The scientific evidence must permit conclusions concerning the effect of the technology on health outcomes;
  3. The technology must improve the net health outcome;
  4. The technology must be as beneficial as any established alternatives;
  5. The improvement must be attainable outside the investigational setting.


Medical Necessity means that health care services (e.g., procedures, treatments, supplies, devices, equipment, facilities or drugs) that a physician, exercising prudent clinical judgment, would provide to a patient for the purpose of preventing, evaluating, diagnosing or treating an illness, injury or disease or its symptoms, and that are:

  1. In accordance with generally accepted standards of medical practice; and
  2. Clinically appropriate in terms of type, frequency, extent, site and duration and considered effective for the patient’s illness, injury or disease; and
  3. Not primarily for the convenience of the patient, physician or other health care provider; and
  4. Not more costly than an alternative service or sequence of services at least as likely to produce equivalent therapeutic or diagnostic results as to the diagnosis or treatment of that patient’s illness, injury or disease.