What Are the Indications for a DXA Scan in Children?

Patient Presentation
A pediatrician provided inpatient hospital care to a school-age girl with steroid-dependent rheumatoid arthritis that had caused osteopenia and extremity fractures.
She had had a dual-energy x-ray absorpiometry (DXA scan) which confirmed baseline osteopenia and was starting bisphosphonate treatment.
Several months later, the same pediatrician was providing care to 3 month old male infant with fractures suspicious for non-accidental trauma.
His mother wanted a ‘bone strength’ test done and was very unhappy when the pediatrician told her that it was not an indicated test because there was no normative data with which to interpret the test even if the test was done.
The pediatrician also thought about a patient from the distant past who was treated for female athlete triad.
The pediatrician could not remember if this athlete had a DXA scan but wondered what the indications for the test were.
The pediatrian performed a computerized PUBMED search and found several primary research articles, position statements from professional organizations, and a couple of review articles on the general topic of bone mass in children.
From these information sources she learned that although DXA scan and other similar tests there are often used in screening and treatment of adults with osteopenia or osteoporosis, because of lack of research data and many other factors that make children different from adults, there are fewer indications for screening and treatment with bone mineral density measurements in children and adolescents.
In general, pediatric patients should have a DXA scan performed if they are at risk for osteopenia and then have a fracture.

Peak bone mass, size and strength reaches a maximum by early adulthood. Factors important to overall bone health include weight bearing physical activity, hormonal balance, body mass, and nutrition.
Causes of osteopenia (i.e. low bone mass) and/or pathological fractures in children include:

  • Genetic (60-80% are caused by a heritable problem)
    • Ehlers-Danlos
    • Fibrous dysplasia
    • Homocystinuria
    • Hypophosphatasia
    • Idiopathic hypercalciuria
    • Marfan’s syndrome
    • Menke’s kinky hair syndrome
    • Osteogenesis imperfecta
  • Endocrine
    • Glucocorticoid excess including steroid medication
    • Growth hormone deficiency
    • Hyperparathyroidism
    • Hyperthyroidism
    • Sex steroid deficiency or resistance
  • Chronic disease
    • Anorexia nervosa
    • Female athlete triad with amenorrhea
    • Celiac disease
    • Cystic fibrosis
    • Diabetes, type 1
    • Inflammatory bowel disease
    • Malignancy
    • Post-transplantation
    • Renal failure
    • Rheumatological diseases
    • Sickle cell anemia
    • Systemic lupus erythematosus
    • Thalassemia
  • Musculoskeletal/Neurological associated with immobilization
    • Cerebral palsy
    • Muscular dystrophy
    • Paraplegia
    • Spina bifida
  • Other
    • Idiopathic juvenile osteoporosis
    • Idiopathic scoliosis

Several methods may be available for performing bone densitometry, but dual-energy x-ray absorpiometry (DXA scan) is the preferred method for children and adolescents because it is widely available, is quick to perform, precise, has better safety, and has the most normative data available.
DXA alone does not make the diagnosis of osteoporosis – osteoporosis requires osteopenia and clinically significant fractures.
Low bone mineral density should be diagnosed only when the Z-scores on the testing are less than or equal to 2 standard deviations below the mean when adjusted for age, gender and body size when appropriate.

Learning Point
According to the International Society for Clinical Densitometry, DXA scan in children and adolescents (ages 5-19 years) should be considered in:

  • Patients being considered for or before beginning therapeutic treatment for osteopenia or osteoporosis
  • Patients on therapeutic treatment being monitored (minimum 6 month intervals between measurements)
  • For fracture prediction, mainly in children with previous clinically significant fractures. Clinically significant fractures are defined as fracture of long bones in the lower extremities, vertebral compression fractures, or two or more long-bone fractures of the upper extremities.
    • Patients with primary bone diseases should be measured at fracture presentation
    • Patients with potential secondary diseases should be measured at fracture presentation
    • Patients with chronic immobilization should be measured at fracture presentation
    • Patient with thalassemia major should be measured at the earlier of either fracture presentation or at 10 years of age.

Additional evaluation for children and adolescents at risk for osteopenia or osteoporosis should include a comprehensive nutritional and physical activity history, review of underlying disease and treatments, 25-hydroxy Vitamin D level (the storage form of Vitamin D), and laboratory testing of hormonal status.

Questions for Further Discussion
1. What local facilities provide bone densitometry for children and adolescents?
2. Who are my local experts that could help me take care of a child or adolescent with an abnormal DXA scan?

Related Cases

To Learn More
To view pediatric review articles on this topic from the past year check PubMed.

Information prescriptions for patients can be found at MedlinePlus for this topic: Osteoporosis

To view current news articles on this topic check Google News.

To view images related to this topic check Google Images.

Bachrach LK. Osteoporosis and measurement of bone mass in children and adolescents.
Endocrinol Metab Clin North Am. 2005 Sep;34(3):521-35, vii.

Bachrach LK. Assessing bone health in children: who to test and what does it mean?
Pediatr Endocrinol Rev. 2005 Feb;2 Suppl 3:332-6.

International Society for Clinical Densitometry. Official Positions.
Available from the Internet at http://www.iscd.org/Visitors/positions/OfficialPositionsText.cfm (rev. 2007, cited 2/15/2008).

ACGME Competencies Highlighted by Case

  • Patient Care

    3. Informed decisions about diagnostic and therapeutic interventions based on patient information and preferences, up-to-date scientific evidence, and clinical judgment is made.
    4. Patient management plans are developed and carried out.
    6. Information technology to support patient care decisions and patient education is used.
    7. All medical and invasive procedures considered essential for the area of practice are competently performed.
    8. Health care services aimed at preventing health problems or maintaining health are provided.
    9. Patient-focused care is provided by working with health care professionals, including those from other disciplines.

  • Medical Knowledge
    10. An investigatory and analytic thinking approach to the clinical situation is demonstrated.
    11. Basic and clinically supportive sciences appropriate to their discipline are known and applied.

  • Practice Based Learning and Improvement
    12. Evidence from scientific studies related to the patients’ health problems is located, appraised and assimilated.
    13. Information about other populations of patients, especially the larger population from which this patient is drawn, is obtained and used.
    14. Knowledge of study designs and statistical methods to appraisal clinical studies and other information on diagnostic and therapeutic effectiveness is applied.
    15. Information technology to manage information, access on-line medical information and support the healthcare professional’s own education is used.

  • Professionalism
    20. Respect, compassion, and integrity; a responsiveness to the needs of patients and society that supercedes self-interest; accountability to patients, society, and the profession; and a commitment to excellence and on-going professional development are demonstrated.

  • Systems Based Practice
    23. Differing types of medical practice and delivery systems including methods of controlling health care costs and allocating resources are known.
    24. Cost-effective health care and resource allocation that does not compromise quality of care is practiced.

    Donna M. D’Alessandro, MD
    Professor of Pediatrics, University of Iowa Children’s Hospital

    April 14, 2008