When should a Dual-Energy X-ray Absorptiometry (DEXA) scan be performed after bariatric surgery to assess bone mineral density?

DEXA Scanning After Bariatric Surgery

According to the European Association for the Study of Obesity (EASO), DEXA scans should be performed every two years in patients who have undergone bariatric-metabolic surgery to monitor bone mineral density. 1

Rationale for DEXA Monitoring After Bariatric Surgery

• Bariatric surgery is associated with clinically significant bone mineral density (BMD) loss, with over 60% of patients experiencing significant BMD reduction within 6 months after surgery 2
• This bone loss is persistent over time and predominantly affects the femoral region 2
• BMD loss after bariatric surgery is strongly associated with weight loss percentage 2
• Different surgical techniques have varying impacts on bone health, with hypoabsorptive and mixed techniques (DS/SADIS and RYGB) associated with greater BMD loss than restrictive techniques (sleeve gastrectomy) 3

Timing of DEXA Scans

• Initial DEXA scan: Should be performed before bariatric surgery to establish baseline bone mineral density 2
• Follow-up DEXA scans: Should be performed at regular intervals after surgery:
  • First follow-up: 12 months post-surgery 2, 4
  • Subsequent follow-ups: Every two years as recommended by the European Association for the Study of Obesity 1
  • Continue annual monitoring until weight has stabilized 2

Special Considerations

• Bone loss after bariatric surgery primarily affects the trabecular compartment rather than the cortical compartment 3
• DXA and QCT measurements may show discordant results, particularly at the hip, due to artifacts induced by large changes in body weight after bariatric surgery 5
• Despite the significant decrease in BMD, actual cases of osteoporosis after bariatric surgery are rare, though osteopenia may develop 2

Preventive Measures

• Systematic vitamin D and calcium supplementation is recommended for all bariatric surgery patients 2
• Moderate physical activity, particularly weight-bearing exercise, should be encouraged to enhance muscle health and minimize bone loss 1
• Maintaining glucose control is important as poor glycemic control correlates with increased fracture risk 1

Risk Factors for Greater Bone Loss

• Higher percentage of excess weight loss 2
• Hypoabsorptive surgical techniques (Roux-en-Y gastric bypass, duodenal switch) versus restrictive techniques (sleeve gastrectomy) 3
• Postmenopausal status in women 4
• Pre-existing risk factors for osteoporosis 1

Common Pitfalls

• Relying solely on DXA measurements without considering potential artifacts from significant weight loss 5
• Failing to establish a pre-surgical baseline for comparison 2
• Neglecting to continue monitoring after the initial post-surgical period 2
• Not differentiating between surgical techniques when assessing bone loss risk 3

By following these guidelines for DEXA scanning after bariatric surgery, clinicians can effectively monitor and address potential bone health issues in this high-risk population.