Challenge of the Week / Basic Science / 08.14.20

A 12-year-old male patient with a poorly controlled seizure disorder has been on high-dose anticonvulsants for 7 years. The patient sustains a low-energy fracture, and his primary care provider orders a dual x-ray absorptiometry (DXA) scan, which indicates a bone mineral density (BMD) measurement of 1.4 standard deviations below normal. Which of the following makes the interpretation of these results challenging?
  • It is not clear what skeletal site was measured.
  • The most widely validated technique to evaluate bone loss is DXA applied to standardized sites of biological relevance, including the hip, spine, and forearm.

  • Anticonvulsant medications affect bone mineral composition that cannot be measured by DXA.
  • The most widely validated technique to measure BMD is DXA, regardless of the root cause of impacts on bone mineral composition.

  • DXA scans are not an appropriate test for children <18 years old.
  • The most widely validated technique to measure BMD is DXA, and diagnostic criteria based on the T-score for BMD are a recommended entry criterion for the development of pharmaceutical interventions in osteoporosis.

  • The normal comparator for bone mineral density measurements is a healthy young Caucasian female.
  • Osteoporosis is defined by the World Health Organization (WHO) as a BMD that lies 2.5 standard deviations or more below the average value for young healthy women (a T-score of <-2.5 SD).

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