Common surgery to lose weight among teenagers and adolescents could weaken the bones, finds study
While many adolescents and teenagers consider going for weight-loss surgeries, researchers have found that one such operation that is common among them has harmful effects on bones. According to the team from Harvard Medical School, Boston, the surgery called “sleeve gastrectomy” weakens the bones.
In a sleeve gastrectomy, approximately 75% of the stomach is removed to restrict food intake and induce weight loss. It results in a typically round stomach taking on the shape of a tube or sleeve. The analysis suggests that adolescents who underwent sleeve gastrectomy had bone loss and an increase in bone marrow fat, despite the marked loss of body fat. The number of sleeve gastrectomy procedures performed on adolescents increased 100-fold from 2005 to 2014, according to the authors. The American Society for Metabolic & Bariatric Surgery (ASMBS) estimates that overall, among weight loss procedures in the US, sleeve gastrectomy has gone up from 17.8% in 2011 to 61.4%.
“Childhood obesity is a major public health issue that has increased over the last 10 years. Sleeve gastrectomy is the most common bariatric surgery procedure performed in children and adults. While weight-loss surgery is successful for weight loss and improving metabolic disorders, it has negative effects on bone,” explains lead investigator Dr Miriam A Bredella, professor of radiology at Harvard Medical School, and vice-chair of the Department of Radiology at Massachusetts General Hospital in Boston.
The findings are being presented at RSNA (Radiological Society of North America) 2020, the 106th scientific assembly and annual meeting of radiologists, radiation oncologists, medical physicists, and related scientists.
The study examined 52 adolescents with moderate to severe obesity, 26 of whom underwent sleeve gastrectomy. The other 26 were in the control group. The mean age was 17.5 years, and the mean body mass index (BMI) was 45. A BMI of 30 or above is considered obese. Thirty-eight of the study participants were girls. “In adults, bariatric surgery can have long-term effects on bone, leading to higher fracture risk. We wanted to determine the effects of sleeve gastrectomy performed on adolescents during the crucial years when bone mass is being accrued,” says Dr Bredella.
Before and 12 months after sleeve gastrectomy (or no surgery), the patients underwent quantitative CT of the lumbar spine, to quantify volumetric bone mineral density. Quantitative CT is a highly accurate technique for detecting changes in volumetric bone mineral density after extreme weight loss, say authors. Some studies have shown that bone marrow fat responds to changes in nutrition and may serve as a biomarker for bone quality. “Therefore, patients underwent proton MR spectroscopy to quantify bone marrow fat of the lumbar spine,” the team adds.
The analysis reveals that a year after the surgery, the adolescents who underwent sleeve gastrectomy lost 34 (+/-13) kg, or 75 (+/-28) pounds, while there was no significant change in weight in the control group. Compared to the controls, sleeve gastrectomy patients had a significant increase in bone marrow fat and a decrease in bone density in the lumbar spine.
According to Dr Bredella, the loss of bone density following sleeve gastrectomy was expected “because greater weight-bearing strengthens bones”. Besides a loss of bone density, other effects of weight-loss surgery include disruption of hormones and nutrients important for bone health. “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,” emphasizes Dr Bredella.