Effects of Gastric Bypass Surgery and Calcium Metabolism and the Skeleton

Obesity is a chronic illness of staggering proportions. Because weight loss through diet and exercise is difficult to attain and maintain, there has been escalating interest in bariatric surgery, including Roux-en-Y gastric bypass. Gastric bypass surgery results in long-term weight loss, dramatic improvement in comorbidities such as diabetes, and decreased mortality. Emerging evidence suggests, however, that gastric bypass may have negative effects on bone health. Because of the serious consequences of osteoporosis and fracture, this is of great concern. This study of the effects of gastric bypass on calcium metabolism and the skeleton may positively impact the clinical care of gastric bypass patients by their surgeons, primary care providers, and endocrinologists. Further, the knowledge gained may inform future investigation into the relationships between obesity, weight loss, and bone biology.

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Key information

Conditions

Obesity, Morbid Body Weight Body Weight Changes Calcium Metabolism Disorders Gastric Bypass Metabolic Diseases Nutrition Disorders Nutritional and Metabolic Diseases Obesity Overnutrition Overweight Pathological Conditions, Signs and Symptoms Signs and Symptoms Weight Loss

Age range

25 year–70 year

Sex eligibility

All sexes

Study type

Observational

Primary location

San Francisco VA Medical Center, San Francisco, CA

San Francisco, California, 94121, United States

Who can participate

Healthy volunteers accepted: No

Only the study team can determine whether someone qualifies for participation.

Inclusion criteria

Scheduled to undergo gastric bypass surgery. Please note that to be eligible, one must already be working with a bariatric surgeon and with plans in place to undergo gastric bypass. This study is unable to arrange or pay for gastric bypass surgery.

Exclusion criteria

Perimenopausal women
Known intestinal malabsorption
Prior bariatric surgery
Use of medications known to impact bone and mineral metabolism
Disease known to affect bone
Illicit drug use or alcohol use >3 drinks/day
Serum calcium >10.2 mg/dL
Calculated creatinine clearance <30 mL/min
Weight >350 pounds
Wrist circumference >12 inches or calf circumference >17 inches

Treatment and study plan

Primary outcomes

Change in Intestinal Calcium Absorption

Time frame: 6 months (between baseline and 6 months)

Change in fractional calcium absorption, determined by dual stable isotope method.

Fractional calcium absorption is the fraction of ingested calcium that is absorbed, which is expressed here as the percentage of ingested calcium that is absorbed. The 6-month change is the mean difference in percentage absorption between time points. For example, if fractional calcium absorption were to decrease from 30% preoperatively to 25% at the 6-month postoperative time point, the change in fractional calcium absorption would be -5%.

Secondary outcomes

Areal Bone Mineral Density (BMD) at the Femoral Neck

Time frame: 12 months post-operatively (between baseline and 12 months)

Areal BMD at the femoral neck by dual-energy X-ray absorptiometry (DXA). The 12-month change is the percentage change between the 12 month and baseline time points.
Trabecular Number at the Tibia

Time frame: 12 months post-operatively (between baseline and 12 months)

Trabecular number at the tibia by high-resolution peripheral quantitative computed tomography (HR-pQCT). The 12-month change is the percentage change between the 12 month and baseline time points. HR-pQCT images were analyzed using the manufacturer's standard clinical evaluation protocol, with trabecular structure extracted using a threshold-based binarization process.

Sponsors and collaborators

Lead sponsor

VA Office of Research and Development

Fed

Registry information

Official study title

Effects of Gastric Bypass Surgery on Calcium Metabolism and the Skeleton

Important dates

Study start: 2011
Primary completion: 2014
Study completion: 2015
First posted: Apr 7, 2011
Registry last updated: Mar 15, 2019

OpenTrials presents study information sourced from ClinicalTrials.gov. The official registry record should be consulted for the latest information.

View the official ClinicalTrials.gov record (opens in a new tab)

This listing is for discovery and informational purposes only. It is not medical advice, does not guarantee that a study is recruiting, and does not determine eligibility. Contact the study team and a qualified healthcare professional when considering participation.

Published trials that share one or more normalized conditions with this study.

Completed