Sleeve gastrectomy in obese adolescents may affect bone health

Adolescents with obesity who undergo sleeve gastrectomy may be at risk of poor bone health, according to a small study presented at the recent annual meeting of the Radiological Society of North America (RSNA 2020).

“Adolescents who underwent sleeve gastrectomy had bone loss and an increase in bone marrow fat, despite marked loss of body fat,” said lead researcher Professor Miriam Bredella from Harvard Medical School and Massachusetts General Hospital, Boston, Massachusetts, US. 

“While weight-loss surgery is successful for weight loss and improving metabolic disorders, it has negative effects on bone,” she noted.

Participants in this prospective study were 52 adolescents with moderate to severe obesity (mean age 17.5 years, 38 female, mean BMI 45 kg/m²). Of these, 26 underwent sleeve gastrectomy and the other 26 served as non-surgical controls. All participants underwent quantitative computed tomography (CT) of the lumbar spine at baseline (before sleeve gastrectomy) and 12 months after surgery or no surgery to assess volumetric bone mineral density (BMD).

Adolescents who underwent sleeve gastrectomy experienced a 36 kg weight loss compared with 0.2 kg loss among those who did not undergo surgery (p<0.0001). [RSNA 2020, abstract PD-1A-48]

Volumetric BMD of the lumbar spine was significantly reduced among individuals who underwent sleeve gastrectomy compared with the control group (p=0.046).

There was a significant increase in lumbar marrow adipose tissue (MAT) between baseline and 12-months post-surgery in patients who underwent sleeve gastrectomy (p=0.013) but there was no significant difference compared with the control group (p=0.3). However, MAT of the femur and tibia was significantly decreased in the surgical vs control group (p=0.049 and p=0.006, respectively).

Over the 12-month period, change in lumbar volumetric BMD was inversely associated with lumbar MAT (r=-0.42; p=0.013), while there was no significant association noted between change in volumetric BMD and peripheral MAT (p>0.1).

“Childhood obesity has increased more than tenfold over the last 4 decades,” said Bredella. This is a major public health issue as childhood obesity can lead to early development of other diseases such as diabetes and heart or fatty liver disease.

Bariatric surgery in adults, while highly effective for weight loss, can lead to an increased risk of fracture. This is due to the disruption in hormones and nutrients that are critical for bone health as well as reduced weight bearing.

“We wanted to determine the effects of sleeve gastrectomy performed on adolescents during the crucial years when bone mass is being accrued,” said Bredella.

“[We found that] sleeve gastrectomy, the most common weight-loss surgery performed in children and adults, decreases bone density in adolescents,” she said.

“Sleeve gastrectomy also causes fat accumulation within bones of the lumbar spine which weakens bone, [this] despite significant loss of body fat,” she added.

The results highlight the importance of strategies to protect bone health in adolescents. “We need to identify mechanisms that will help prevent bone loss in these patients and to make adolescents with obesity more aware of bone health. Adolescence is the critical time for bone mass accrual, and any process that interferes with bone accrual during this time can have dire consequences later in life,” Bredella pointed out.

“It will [also] be important to find new ways to treat bone loss in children undergoing weight loss surgery,” she concluded.