Metabolic Bone Disease

Treatment options do exist for individuals who develop osteoporosis as a result of weight loss surgery.

Gastric Bypass and Duodenal Switch both involve bypassing the duodenum, which results in calcium malabsorption. In fact, calcium malabsorption occurs with any surgical procedure that requires bypassing the duodenum, as the duodenum is responsible for absorbing the majority of calcium. Gastric Bypass and Duodenal Switch patients require calcium supplementation and even with complete supplementation, calcium malabsorption may still cause many patients to present signs of malabsorptive metabolic bone disease. Blood levels of vitamin-D, calcium and parathyroid hormone (PTH) are monitored regularly to assess calcium metabolism. Maintaining the proper levels of vitamin-D is extremely important as vitamin-D plays a pivotal role in maintaining normal calcium levels.

Situations easily corrected that may interfere with calcium absorption after weight loss surgery procedures such as gastric bypass and duodenal switch include the following:

  • supplementing with the wrong form of calcium
  • consuming iron supplements that interfere with calcium absorption

There are multiple forums of calcium but not all forms of calcium are equally and/or readily absorbed. While many weight loss surgery patients are advised to take calcium carbonate (the most common form of calcium), calcium carbonate is not easily absorbed. Although calcium carbonate is effective in kidney stone prevention for some patients after weight loss surgery, calcium carbonate is a poor choice of calcium supplement for the prevention of osteoporosis after weight loss surgery. Bariatric surgical patients need to supplement with a form of calcium that is readily absorbed. Calcium citrate and calcium apatite are two forms of calcium that are readily absorbed and are better suited to meet the needs of the post weight loss surgery patient.

Calcium absorption can be impacted negatively by iron supplements and it is generally recommended that calcium and iron pills not be taken within two hours of each other; this of course makes it more difficult to adhere to a supplement routine. Maximal absorption of both iron and calcium occur in the duodenum, which is partly why metabolic bone disease and anemia frequently appear together after Gastric Bypass and Duodenal Switch. Patients who experience iron deficiency often supplement with iron so aggressively, it interferes with their calcium absorption. While trying to increase their iron levels, patients exacerbate their calcium deficiency, with an end result of both anemia and osteoporosis. When iron pills fail to work, many patients require iron infusions. Even though this may be a cause of concern in many post weight loss surgery patients, it is easier to treat iron deficiency with infusions than it is to treat calcium deficiency the same way. One is often faced with making one of two decisions:

  1. supplementing with iron pills while risking acceptable calcium absorption
  2. receiving iron infusions and allow calcium pills to be more readily absorbed 

Taking iron infusions is the clear choice.

Reversal of a patients weight loss surgery procedure may be required if signs of metabolic bone disease persist despite high dose calcium supplementation and healthy levels of vitamin-D. If reversal is necessary, the reversal should be limited to the portion of the operation that impacts calcium malabsorption and should not result in excessive weight re-gain. For individuals who have had gastric bypass, reversal may include conversion to Vertical Sleeve Gastrectomy, with or without Ileal Transposition or Omentectomy. The purpose of this is to reestablish normal flow through the duodenum while allowing the neuro-endocrine system to act as a brake for weight loss maintenance. Reversal of the Duodenal Switch requires a High Duodenal Ileal Transposition. This will accomplish the desired effect without reversing the entire weight loss surgical procedure. Iron absorption also improves after revision weight loss surgery, although this is not the primary goal of revision bariatric surgery for metabolic bone disease.

Next: Vitamin Deficiencies and Weight Loss Surgery >>

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This information has been provided by Dr. John Husted. To learn more about Dr. Husted, please visit http://www.johnhustedmd.com/.

 

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