From the Guidelines
After bariatric surgery, a follow-up bone mineral density (BMD) test should be performed 1-2 years after the initial procedure for a 40-year-old patient with no history of fractures, as shorter intervals between BMD testing may be indicated in the presence of factors associated with rapid change in bone mineral density, such as bariatric surgery 1. When determining the timing of repeat BMD measurement, several factors should be considered, including:
- The patient's age and baseline BMD
- The type of pharmacological treatment
- The presence of clinical factors associated with bone loss
- The occurrence of fractures or development of new risk factors According to the latest ISCD 2023 update, repeat BMD testing intervals must be individualized considering these factors 1. In the case of bariatric surgery, the potential for rapid bone loss due to malabsorption and other factors associated with the procedure necessitates closer monitoring, supporting the recommendation for a follow-up BMD test within 1-2 years after surgery 1. Subsequent BMD testing should then be conducted based on the individual's clinical circumstances, taking into account any changes in BMD, the development of new risk factors, or the occurrence of fractures, with the goal of optimizing bone health management and preventing secondary fractures 1. Regular monitoring of serum calcium, vitamin D, and parathyroid hormone levels, alongside BMD testing, is also crucial for ensuring optimal bone health management following bariatric surgery, and patients should maintain adequate calcium intake, vitamin D supplementation, and regular weight-bearing exercise to support bone health.
From the Research
BMD Measurement After Bariatric Surgery
- The European Calcified Tissue Society (ECTS) recommends treating vitamin D deficiency, achieving adequate daily calcium and protein intake, and promoting physical activity before and following bariatric surgery 2.
- Bariatric procedures with a malabsorptive component, such as Roux-en-Y Gastric bypass (RYGB), have been associated with the highest risk of fracture and bone loss 2, 3.
- Studies have shown that bone mineral density (BMD) loss is common after bariatric surgery, with a significant reduction in BMD observed in 62.1% of patients at 6 months and 71.6% at 12 months after surgery 4.
- The timing of BMD measurement after bariatric surgery is not explicitly stated in the provided studies, but it is recommended to perform serial BMD measurements and individualize therapy with risk factors control 5, 4.
Factors Influencing BMD Loss
- BMD loss is related to the reduction in body mass index (BMI), weight loss, fat mass, and lean mass 4.
- Excess weight loss percentage is significantly associated with the reduction in BMD 4.
- Vitamin D and parathyroid hormone (PTH) levels are also correlated with BMD changes, with a direct correlation between BMD and vitamin D increase, and an inverse correlation between BMD increase and PTH decrease 6.
Specific Procedures and BMD Changes
- RYGB has been associated with greater reduction in BMD, greater increase in bone turnover markers, and higher risk of fractures compared with sleeve gastrectomy (SG) 2.
- SG has been shown to result in a progressive increase in BMD during the first and second year after surgery, with a direct correlation between BMD and vitamin D increase 6.