Loss of bone density observed after bariatric surgery in adolescents

Although bariatric surgery is quite effective for weight loss in obese adolescents, it can also weaken bones, according to a prospective longitudinal study.

Within a year of undergoing sleeve gastrectomy, teenagers saw a dose of 12 mg/cm³ decrease in mean vertebral bone mineral density (BMD), while non-surgical controls saw no change (P<0.001), reported Miriam Bredella, MD, of Massachusetts General Hospital in Boston, and colleagues.

Patients who underwent sleeve gastrectomy also saw a dose of 6 mg/cm³ reduction in cortical vertebral BMD compared to a dose of 4 mg/cm³ reduction in the number of those who did not opt ​​for surgery (P=0.52), the group wrote in the Journal of Bone and Mineral Research.

Additionally, sleeve patients had a significant 2.8% decrease in flexion stiffness, while non-surgical controls had a 2.5% increase in this measure.

While other measures including body strength, thigh muscle area, visceral adipose tissue, and trabecular vertebral BMD initially appeared to decrease significantly for surgical patients, these differences were no longer significant after adjustment. for the 12-month change in body mass index (BMI). Essentially, these reductions were all attributable to the lower BMI that occurred after surgery.

“Weight-loss surgery is highly effective in treating obesity and obesity-associated comorbidities in obese adolescents and young adults; however, it can result in loss of bone density and strength,” Bredella said. in a press release.

“We hope our study will raise awareness of the importance of bone health after weight-loss surgery, so doctors can ensure children are getting a healthy diet with enough calcium and vitamin D and getting better. engage in weight-bearing activity to build muscle mass, which is good for the bones,” she added.

These results are not necessarily a surprise, because several forms of bariatric surgery are associated with reduced nutrient absorption after removal of portions of the stomach. Post-surgical nutritional supplementation is therefore vital for patients.

However, to keep this in perspective, previous studies have also linked obesity with a higher risk of weaker bones.

Bredella’s group explained that all sleeve patients received calcium and vitamin D supplementation based on 25OHD levels: those with 25OHD levels of 20 to 30 ng/mL received 4,000 IU/day; those with levels of 12 to 20 ng/mL received 50,000 IU/week for 2 months; and those with levels below 12 ng/mL took 50,000 IU/week for 3 months.

There was no significant drop in calcium, phosphorus and vitamin D and no increase in parathyroid hormone levels after surgery. “This suggests that BMI-independent reductions in flexural strength and cortical BMD reflect alterations other than mechanical unloading or inadequate calcium or vitamin D intake,” Bredella and his team wrote.

The prospective study compared 29 patients who underwent sleeve gastrectomy with 30 non-surgical controls. All participants had to be between the ages of 13 and 25 and moderately to severely obese (BMI ≥ 35) with at least one comorbidity or BMI ≥ 40. None of the teens could weigh more than 441 pounds due to weight limitations CT and MRI scans.

The vast majority were women; Mean baseline BMI in sleeve patients was 47.4 and weight was 294.1 lb. Approximately 45% of sleeve patients were white, 28% were Hispanic, and 17% were black.

During the one-year follow-up, the sleeved patients lost an average of 75.6 pounds, while the nonsurgical controls experienced no significant weight change. Sleeve patients also saw their BMI drop by 12.3 points.

“A longer follow-up period is needed to determine whether deleterious changes in spinal strength will continue and lead to spinal fractures,” the group concluded.