Bone Mineral Density

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Contents 1 More Specific Terms 2 Introduction 3 Indications 4 Contraindications 5 Clinical-significance 6 Methods 7 Interpretation 8 More General Terms 9 Additional Terms 10 References

More Specific Terms

• dual energy X-ray absorptiometry (DEXA)

Introduction

• Also see screening for osteoporosis.

Indications

• all women > 65 years of age & all men > 70 years of age [1]

• USPSTF concludes not enough evidence to determine whether routine screening is beneficial or harmful for men [6]

• postmenopausal women < 65 & men < 70 years of age with one additional risk factor for osteoporosis
• patients considering therapy for osteoporosis for which bone mineral density measurements would affect the decision
• radiographic findings suggestive of osteoporosis
• men or women on chronic oral glucocorticoids for > 3 months [1]
• primary hyperparathyroidism
• monitoring therapeutic response to bisphosphonates is controversial

Contraindications

• do not repeat in < 2-5 years unless patient is on long-term glucocorticoid therapy [1]

Clinical-significance

• bone mineral density ( BMD) increases with childhood growth & reaches a peak in the 3rd decade of life
• subsequently, a slow decline in BMD occurs
• a more acute loss in BMD occurs in women at the time of menopause
• BMD T-score <= -2.50 defines osteoporosis
  
• factors increasing bone mineral density

• leptin inhibits bone resorption
• insulin-like growth factor
• growth hormone
• estrogen
• testosterone
  

• etiology of low BMD

• CHF ( deconditioning)
• COPD ( deconditioning, steroids)
• kyphosis
• lactose intolerance
• liver disease
• malabsorption
• amenorrhea
• early menopause
• oophorectomy
• hyperthyroidism or over-replacement of thyroid hormone
• increased PTH
• increased prolactin
• low calcium diet
• inhaled steroids do not affect BMD in postmenopausal women [3]
• low BMI [4]
  

• polymorphisms in IL-6 gene influence BMD

Methods

• Bone mineral density measurements:

• dual energy X-ray absorptiometry ( DEXA)
• single photon absorptiometry (SPA)
• dual photon absorptiometry ( DPA)
• quantitative computed tomography

Interpretation

• Numerical scoring of BMD:

• see dual energy X-ray absorptiometry ( DEXA)

• measurements are imprecise: [5]

• bone mineral density measurements within individual patients vary more than measurements between bisphosphonate & placebo recipients [5]

More General Terms

• radiography (diagnostic imaging, roentgenography)

Additional Terms

• bone
• FRAX fracture risk assessment tool
• hip fracture
• osteoporosis

References

1. Medical Knowledge Self Assessment Program (MKSAP) 11, 14, 15, American College of Physicians, Philadelphia 1998, 2006, 2009
2. Iris Cantor - UCLA Women's Health Center Osteoporosis Evaluation
3. Journal Watch 23(6):49, 2003 Elmstahl S et al Is there an association between inhaled corticosteroids and bone density in postmenopausal women? J Allergy Clin Immunol 111:91, 2003 PMID: [1]
4. Fernandez-Garcia D et al Thin healthy women have a similar low bone mass to women with anorexia nervosa. Br J Nutr 2009 Mar 23; [e-pub ahead of print] <PubMed> PMID: [2] <Internet> [3]
5. Bell KJL Value of routine monitoring of bone mineral density after starting bisphosphonate treatment: secondary analysis of trial data BMJ 2009;338:b2266 [4]
6. U.S. Preventive Services Task Force Screening for Osteoporosis: U.S. Preventive Services Task Force Recommendation Statement Annals of Internal Medicine, January 17, 2011 <PubMed> PMID: [5] <Internet> [6]
7. National Guideline Clearinghouse
   - Osteoporosis and bone mineral density. American College of Radiology ngc-guideline: [7]

bone mineral density (BMD)