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Perioperative management of bariatric surgery patients: Focus on metabolic bone disease

Cleveland Clinic Journal of Medicine. 2008 May;75(5):333-334, 336, 338, 342-346, 349
May 1, 2008|Cleveland Clinic Journal of Medicine
Susan E. Williams, MD, MS, RD, CNSP, CCD;Karen Cooper, DO;Bradford Richmond, MD;Philip Schauer, MD
Author and Disclosure Information

Susan E. Williams, MD, MS, RD, CNSP, CCD
Director, Center for Nutrition and Metabolic Medicine, Greene Memorial Hospital Advanced Medical Group, Xenia, OH; Assistant Professor of Clinical Medicine, Department of Internal Medicine, Wright State University Boonshoft School of Medicine, Dayton, OH; Chair-elect, Certification Council, International Society of Clinical Densitometry

Karen Cooper, DO
Bariatric and Metabolic Institute, Cleveland Clinic

Bradford Richmond, MD
Director, Musculoskeletal Radiology Fellowship Program, Department of Diagnostic Radiology, Cleveland Clinic; Associate Profesor of Radiology, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University

Philip Schauer, MD
Director, Advanced Laparoscopic and Bariatric Surgery, Bariatric and Metabolic Institute, Cleveland Clinic; Professor of Surgery, Cleveland Clinic Lerner College of Medicine of Case Western Reserve University

Address: Susan Williams, MD, Center for Nutrition & Metabolic Medicine, Greene Memorial Hospital Health Center, 50 North Progress Drive, Xenia, OH 45385; e-mail swilliams@greenehealth.org

Dr. Richmond has disclosed that he has received honoraria from Procter and Gamble for teaching and speaking.

Dr. Schauer has disclosed that he is a consultant for or on the scientific advisory boards of Bard-Davol, Barosense, Baxter, Ethicon Endosurgery, Gore, and Stryker Endoscopy; is on the board of directors and is a partner in Remedy MD; and has received grant support from Invacare.

ABSTRACTChronic vitamin D deficiency, inadequate calcium intake, and secondary hyperparathyroidism are common in obese individuals, placing them at risk for low bone mass and metabolic bone disease. After bariatric surgery, they are at even higher risk, owing to malabsorption and decreased oral intake. Meticulous preoperative screening, judicious use of vitamin and mineral supplements, addressing modifiable risk factors, and monitoring the absorption of key nutrients postoperatively are essential in preventing metabolic bone disease in bariatric surgery patients.

KEY POINTS

  • Metabolic bone disease in obese patients is multifactorial: causes include sequestration of vitamin D in the adipocytes, inadequate nutrition due to chronic dieting, and lack of physical activity.
  • Before bariatric surgery, one must look for and treat preexisting nutritional deficiencies.
  • In the immediate postoperative period, aggressive strategies (ie, giving multivitamins and minerals intravenously and orally) can prevent nutritional deficiencies and secondary bone disease.
  • Postoperatively, many bariatric patients require chewable or liquid supplements to facilitate adequate absorption.
  • Clinical suspicion, timely interventions, and lifelong monitoring can prevent metabolic bone disease in bariatric surgery patients.

Who should undergo DXA?

According to the International Society of Clinical Densitometry, bone density testing is indicated in the general population in women 65 years of age and older, postmenopausal women younger than 65 with risk factors, men 70 and older, adults with fragility fractures, adults taking a medication or having a disease or condition associated with low bone mass or bone loss, any patient being treated for low bone mass (to monitor the treatment effect), and any person in whom evidence of bone loss would affect treatment decisions.58

The National Osteoporosis Foundation recommends initiating therapy to reduce fracture risk in postmenopausal women with a central DXA T score below –2 in the absence of risk factors, and in women with T scores below –1.5 if one or more risk factors is present.34 Therefore, in view of the known risks, the likely need for interventions before surgery, and the ability to prevent the illness and death associated with metabolic bone disease, we recommend that all bariatric surgery patients undergo DXA at baseline as part of the preoperative evaluation.

Improvements in DXA technology

Newer DXA machines can accommodate patients weighing up to 450 pounds (the limit with older machines was 275 pounds for central measurements). In addition to measuring bone density, they also can map the distribution of fat in the body—patients with an android (apple-shaped) distribution are at higher risk of cardiovascular disease than those with a gynecoid (pear-shaped) distribution.59–63 For those patients who cannot be accommodated on a DXA table, DXA of the forearm can be used to assess bone density and fracture risk.

How often should DXA be repeated?

The estimated monitoring time interval is derived from the statistically defined least significant change divided by the anticipated change in bone density over time.64 When estimating the monitoring time interval for changes in body composition, the rate of weight loss and the psychological impact on the patient must be taken into consideration.

In general, DXA testing more frequently than every 2 years remains controversial unless one is initiating, monitoring, or changing therapy or monitoring conditions associated with rapid bone loss such as glucocorticoid therapy. In the bariatric surgery population, however, there is convincing evidence that significant changes may be detected after 12 months that would influence clinical decisions, particularly in the year immediately after surgery.8,9,13,21,27,65

Anabolic and antiresorptive bone drugs

Prescribed medications for the prevention and treatment of osteoporosis should also be an integral part of the treatment plan for at-risk morbidly obese patients. But the decision to prescribe an antiresorptive or bone-forming medication must take into consideration the patient’s risk-benefit profile, including the likelihood of gastrointestinal side effects and his or her ability and willingness to follow specific dosing instructions. Intravenous preparations are now available for patients who cannot absorb or tolerate oral antiresorptive medications. However, specific recommendations about the use of anabolic or antiresorptive bone medications in perioperative bariatric patients have yet to be elucidated.

RECOMMENDATIONS

Although a variety of recommendations have been published, there are no established guidelines for perioperative screening, risk stratification, or management of metabolic bone disease in bariatric surgery patients.7,44,65–67 And the literature remains inconclusive on key issues such as when to start supplements, which biochemical indices should be checked before surgery, whether baseline and annual DXA should be done, and whether antiresorptive agents such as bisphosphonates should be used prophylactically during rapid weight loss.

However, numerous studies and case reports cited here and elsewhere further underscore the ever-present risk of metabolic bone disease in this patient population, and the need for meticulous perioperative and long-term monitoring.44,65–67

Interventions should be individualized: we need to carefully consider the modifiable risk factors, the severity of disease, and the patient’s ability and willingness to participate in his or her care. Modifiable risk factors for progression of bone disease must be addressed in all patients at risk. It is also important to identify patients at high risk for falls due to poor visual acuity, frailty, neuropathy, or dementia and to implement risk management strategies to the degree possible.34

With these caveats in mind, we offer our recommendations (Table 3).

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