Bone Density (DEXA)

What is Osteoporosis?
Osteoporosis is a skeletal condition characterized by compromised bone strength predisposing a person to an increased risk of fractures.
Bone strength reflects integration of four main features:

• Bone density.
• Bone turn over.
• Bone architecture (cross-links).
• Bone minerals.

When and who to test?

• Women >65 years of age and men >70 years of age.
• Clinical evaluation for major and minor risk factors (one major and/or two minor risk factors).
• Chronic glucocorticoid therapy (more than three months of use).
• Fragility fracture or vertebral deformity.

How to measure The Bone Mineral Density?
Dual energy X-ray absorpometry (DEXA) is the most sensitive and accurate method to measure bone mineral density, it is an enhanced form of X-ray in low radiation dose used to measure bone loss. Traditional X-ray cannot measure bone density but it can identify vertebral fractures; whereas Ultrasound is just a screening test machine and it’s not advisable to treat patients according to its results but ask for DEXA test for confirmation.

Most commonly the lower back and hip density is measured for osteoporosis, in children and some adults the whole body is sometimes scanned.

• Follow up should be on the same model device with strict quality assurance measures.
• Recommended time between measures in patients on treatment is 1-2 years.
• Treatment is indicated if BMD <-2.5.
• Prophylaxis and monitoring is indicated if BMD between -1- -2.5 SD.
• If BMD is >-1 no treatment is needed.

Factors that Identify People who should be assessed for Osteoporosis:

1. Major Risk Factors:
   • Age >65 years.
   • Early menopause <40 years.
   • Systemic glucocorticoid >3 months.
   • Vertebral compression fracture.
   • Fragility fracture after the age of 40.
   • Family history of osteoporotic fractures.
   • Propensity to fall.
   • Osteopenia on X-ray.
   • Hypogonadism.
   • Primary hyperparathyroidism.
   • Malabsorption syndromes.
2. Minor Risk Factors:
   • White Asian women.
   • Low dietary calcium.
   • Weight <57 Kg.
   • Weight loss >10% at age of 25.
   • Thin body habitus (BMI <20 Kg/m2).
   • Smoking, increased alcohol and caffeine intake.
   • Prolonged amenorrhea >6 months.
   • Medical conditions predisposing to osteoporosis (Rheumatoid arthritis, hyperthyroidism).
   • Chronic drug intake causing osteoporosis (Heparin, anticonvulsants).
   • Sedative drugs, anxiolytic drugs.
   • Neurological conditions leading to altered vision or proprioception.

Osteoporosis in Men:
Osteoporosis occurs less often in men than in women, because men have larger skeletons, and also because bone loss starts later in life and progresses more slowly (as there is no period of rapid hormonal changes and rapid bone loss). At least half of the cases are secondary. Common causes include medications such as glucocorticoid excess and anticonvulsants, smoking, alcohol abuse, gastrointestinal disease, hypercalciurea and immobilization. BMD test is used for diagnosis.

Treatment includes nutrition, adequate calcium and vitamin D, exercise and medication.

Prevention and Treatment of Osteoporosis:

• Smoking cessation.
• Avoidance of excessive alcohol and caffeine intake.
• Follow regular weight-bearing exercise regimen.
• Avoidance of excessive weight loss.
• Adequate intake of calcium and vitamin D.
• Identify risk factors from history/examination.
• Counseling on lifestyle modification and adequate calcium/vitamin D intake.